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Primary ciliary dyskinesia (PCD), a disorder of the motile cilia, is now recognised as an underdiagnosed cause of bronchiectasis. Accurate PCD diagnosis comprises clinical assessment, analysis of cilia and the identification of biallelic variants in one of 50 known PCD-related genes, including HYDIN. HYDIN-related PCD is underdiagnosed due to the presence of a pseudogene, HYDIN2, with 98% sequence homology to HYDIN. This presents a significant challenge for Short-Read Next Generation Sequencing (SR-NGS) and analysis, and many diagnostic PCD gene panels do not include HYDIN. We have used a combined approach of SR-NGS with bioinformatic masking of HYDIN2, and state-of-the-art long-read Nanopore sequencing (LR_NGS), together with analysis of respiratory cilia including transmission electron microscopy and immunofluorescence to address the underdiagnosis of HYDIN as a cause of PCD. Bioinformatic masking of HYDIN2 after SR-NGS facilitated the detection of biallelic HYDIN variants in 15 of 437 families, but compromised the detection of copy number variants. Supplementing testing with LR-NGS detected HYDIN deletions in 2 families, where SR-NGS had detected a single heterozygous HYDIN variant. LR-NGS was also able to confirm true homozygosity in 2 families when parental testing was not possible. Utilising a combined genomic diagnostic approach, biallelic HYDIN variants were detected in 17 families from 242 genetically confirmed PCD cases, comprising 7% of our PCD cohort. This represents the largest reported HYDIN cohort to date and highlights previous underdiagnosis of HYDIN-associated PCD. Moreover this provides further evidence for the utility of LR-NGS in diagnostic testing, particularly for regions of high genomic complexity., (© 2024. Crown.)

Background:  Patients with lissencephaly typically present with severe psychomotor retardation and drug-resistant seizures. The aim of this study was to characterize the epileptic phenotype in a genotypically and radiologically well-defined patient cohort and to evaluate the response to antiseizure medication (ASM). Therefore, we retrospectively evaluated 47 patients of five genetic forms ( LIS1/PAFAH1B1 , DCX , DYNC1H1 , TUBA1A , TUBG1 ) using family questionnaires, standardized neuropediatric assessments, and patients' medical reports., Results:  All but two patients were diagnosed with epilepsy. Median age at seizure onset was 6 months (range: 2.1-42.0), starting with epileptic spasms in 70%. Standard treatment protocols with hormonal therapy (ACTH or corticosteroids) and/or vigabatrin were the most effective approach for epileptic spasms, leading to seizure control in 47%. Seizures later in the disease course were most effectively treated with valproic acid and lamotrigine, followed by vigabatrin and phenobarbital, resulting in seizure freedom in 20%. Regarding psychomotor development, lissencephaly patients presenting without epileptic spasms were significantly more likely to reach various developmental milestones compared to patients with spasms., Conclusion:  Classic lissencephaly is highly associated with drug-resistant epilepsy starting with epileptic spasms in most patients. The standard treatment protocols for infantile epileptic spasms syndrome lead to freedom from seizures in around half of the patients. Due to the association of epileptic spasms with an unfavorable course of psychomotor development, early and reliable diagnosis and treatment of spasms should be pursued. For epilepsies occurring later in childhood, ASM with valproic acid and lamotrigine, followed by vigabatrin and phenobarbital, appears to be most effective., Competing Interests: None declared., (Thieme. All rights reserved.)

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait, due to a single heterozygous loss-of-function variant, usually in ACVRL1 (encoding activin receptor-like kinase 1 [ALK1]), ENG (encoding endoglin [CD105]), or SMAD4 . In a consecutive single-centre series of 37 positive clinical genetic tests performed in 2021-2023, a skewed distribution pattern was noted, with 30 of 32 variants reported only once, but ACVRL1 c.1231C>T (p.Arg411Trp) identified as the disease-causal gene in five different HHT families. In the same centre's non-overlapping 1992-2020 series where 110/134 (82.1%) HHT-causal variants were reported only once, ACVRL1 c.1231C>T (p.Arg411Trp) was identified in nine further families. In a 14-country, four-continent HHT Mutation Database where 181/250 (72.4%) HHT-causal variants were reported only once, ACVRL1 c.1231C>T (p.Arg411Trp) was reported by 12 different laboratories, the adjacent ACVRL1 c.1232G>A (p.Arg411Gln) by 14, and ACVRL1 c.1120C>T (p.Arg374Trp) by 18. Unlike the majority of HHT-causal ACVRL1 variants, these encode ALK1 protein that reaches the endothelial cell surface but fails to signal. Six variants of this type were present in the three series and were reported 6.8-25.5 (mean 8.9) times more frequently than the other ACVRL1 missense variants (all p -values < 0.0039). Noting lower rates of myocardial infarction reported in HHT, we explore potential mechanisms, including a selective paradigm relevant to ALK1's role in the initiating event of atherosclerosis, where a plausible dominant negative effect of these specific variants can be proposed. In conclusion, there is an ~9-fold excess of kinase-inactive, cell surface-expressed ACVRL1 /ALK1 pathogenic missense variants in HHT. The findings support further examination of differential clinical and cellular phenotypes by HHT causal gene molecular subtypes., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

Inherited cardiomyopathies and arrhythmias (ICAs) are a prevalent and clinically heterogeneous group of genetic disorders that are associated with increased risk of sudden cardiac death and heart failure. Making a genetic diagnosis can inform the management of patients and their at-risk relatives and, as such, molecular genetic testing is now considered an integral component of the clinical care pathway. However, ICAs are characterised by high genetic and allelic heterogeneity, incomplete / age-related penetrance, and variable expressivity. Therefore, despite our improved understanding of the genetic basis of these conditions, and significant technological advances over the past two decades, identifying and recognising the causative genotype remains challenging. As clinical genetic testing for ICAs becomes more widely available, it is increasingly important for clinical laboratories to consolidate existing knowledge and experience to inform and improve future practice. These recommendations have been compiled to help clinical laboratories navigate the challenges of ICAs and thereby facilitate best practice and consistency in genetic test provision for this group of disorders. General recommendations on internal and external quality control, referral, analysis, result interpretation, and reporting are described. Also included are appendices that provide specific information pertinent to genetic testing for hypertrophic, dilated, and arrhythmogenic right ventricular cardiomyopathies, long QT syndrome, Brugada syndrome, and catecholaminergic polymorphic ventricular tachycardia., (© 2023. The Author(s).)

Rapid, cost-effective genomic stratification of structural rearrangements in cancer is often of vital importance when determining treatment; however, existing diagnostic cytogenetic and molecular testing fails to deliver the required speed when deployed at scale. Next-generation sequencing-based methods are widely used, but these can lack sensitivity and require batching of samples to be cost-effective, with long turnaround times. Here we present a novel method for rearrangement detection from genomic DNA based on third-generation long-read sequencing that overcomes these time and cost issues. The utility of this approach for the genomic stratification of patients with acute myeloid leukemia is shown based on detection of four of the most prevalent structural rearrangements. The method not only determines the precise genomic breakpoint for each expected rearrangement but also discovers and validates novel translocations in one-third of the tested samples, 80% of which involve known oncogenes. This method may prove to be a powerful tool for the diagnosis, genomic stratification, and characterization of cancers., (Copyright © 2022 Association for Molecular Pathology and American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Introduction : Familial hypercholesterolaemia (FH) is a common autosomal dominant genetic condition, characterised by elevated LDL cholesterol (LDL-C), leading to premature cardiovascular disease (CVD). Early and accurate diagnosis, with implementation of preventative therapies, has a major impact on reducing premature CVD, morbidity and mortality. Genetic testing is recommended to confirm clinical diagnosis in the proband and enable cascade testing in relatives. There is growing evidence that the risk of CVD conferred by hypercholesterolaemia depends not only on monogenic causes but also on polygenic factors. GENinCode has developed a novel genomic testing system (Lipid inCode ® ) which we have assessed against an accredited National Health Service (NHS UK) genetic screening service in order to validate its diagnostic and clinical utility. Methods : DNA samples from 40 index cases who had been referred for FH testing in an ISO15189-accredited NHS genetic screening service, were retrospectively tested using the Lipid inCode ® assay. The results were compared with those from NHS testing. Results : There was absolute concordance in variant detection between both diagnostic tests for monogenic and polygenic FH, the only difference being in the interpretation and classification of DNA variants based on ACMG guidelines, which did not differ by more than one classification class.  The Lipid inCode ® test was equivalent to the NHS test in providing comprehensive genetic analysis that included the assessment of both monogenic (FH) and polygenic determinants of blood cholesterol and including a pharmacogenomic assessment of predisposition to statin-related myopathy. Conclusion : The Lipid inCode ® diagnostic test can be undertaken with rapid turnaround and gave the same results as those reported by standard NHS genetic laboratory testing. In addition to assessment of monogenic FH, the Lipid inCode ® assay provides additional genetic data, such as polygenic factors contributing to hypercholesterolaemia, a polygenic risk score (PRS) for coronary artery disease (CAD), pharmacogenomic testing for statin myopathy, and genetic predisposition to raised Lp(a)., Competing Interests: MB is a clinical advisor to GENinCode. DMR is a clinical and scientific advisor to GENinCode. TK, EN and WB have no conflicts of interest to declare. RB is a clinical and scientific advisor to GENinCode. MC and CF are GENinCode employees. MW has no conflicts of interest to declare., (Copyright ©2021 The Author(s).)

Purpose: Biallelic hypomorphic variants in PPA2, encoding the mitochondrial inorganic pyrophosphatase 2 protein, have been recently identified in individuals presenting with sudden cardiac death, occasionally triggered by alcohol intake or a viral infection. Here we report 20 new families harboring PPA2 variants., Methods: Synthesis of clinical and molecular data concerning 34 individuals harboring five previously reported PPA2 variants and 12 novel variants, 11 of which were functionally characterized., Results: Among the 34 individuals, only 6 remain alive. Twenty-three died before the age of 2 years while five died between 14 and 16 years. Within these 28 cases, 15 died of sudden cardiac arrest and 13 of acute heart failure. One case was diagnosed prenatally with cardiomyopathy. Four teenagers drank alcohol before sudden cardiac arrest. Progressive neurological signs were observed in 2/6 surviving individuals. For 11 variants, recombinant PPA2 enzyme activities were significantly decreased and sensitive to temperature, compared to wild-type PPA2 enzyme activity., Conclusion: We expand the clinical and mutational spectrum associated with PPA2 dysfunction. Heart failure and sudden cardiac arrest occur at various ages with inter- and intrafamilial phenotypic variability, and presentation can include progressive neurological disease. Alcohol intake can trigger cardiac arrest and should be strictly avoided., (© 2021. The Author(s).)

Our understanding of cystic fibrosis (CF) has grown exponentially since the discovery of the cystic fibrosis transmembrane conductance regulator ( CFTR ) gene in 1989. With evolving genetic and genomic tools, we have come to better understand the role of CFTR genotypes in the pathophysiology of the disease. This, in turn, has paved the way for the development of modulator therapies targeted at mutations in the CFTR , which are arguably one of the greatest advances in the treatment of CF. These modulator therapies, however, do not target all the mutations in CFTR that are seen in patients with CF and, furthermore, a variation in response is seen in patients with the same genotype who are taking modulator therapies. There is growing evidence to support the role of non-CFTR modifiers, both genetic and environmental, in determining the variation seen in CF morbidity and mortality and also in the response to existing therapies. This review focusses on key findings from studies using candidate gene and genome-wide approaches to identify CF modifier genes of lung disease in cystic fibrosis and considers the interaction between modifiers and the response to modulator therapies. As the use of modulator therapies expands and we gain data around outcomes, it will be of great interest to investigate this interaction further. Going forward, it will also be crucial to better understand the relative influence of genomic versus environmental factors. With this understanding, we can truly begin to deliver personalised care by better profiling the likely disease phenotype for each patient and their response to treatment.

Background: Primary ciliary dyskinesia (PCD), a genetically heterogeneous condition enriched in some consanguineous populations, results from recessive mutations affecting cilia biogenesis and motility. Currently, diagnosis requires multiple expert tests., Methods: The diagnostic utility of multigene panel next-generation sequencing (NGS) was evaluated in 161 unrelated families from multiple population ancestries., Results: Most (82%) families had affected individuals with biallelic or hemizygous (75%) or single (7%) pathogenic causal alleles in known PCD genes. Loss-of-function alleles dominate (73% frameshift, stop-gain, splice site), most (58%) being homozygous, even in non-consanguineous families. Although 57% (88) of the total 155 diagnostic disease variants were novel, recurrent mutations and mutated genes were detected. These differed markedly between white European (52% of families carry DNAH5 or DNAH11 mutations), Arab (42% of families carry CCDC39 or CCDC40 mutations) and South Asian (single LRRC6 or CCDC103 mutations carried in 36% of families) patients, revealing a striking genetic stratification according to population of origin in PCD. Genetics facilitated successful diagnosis of 81% of families with normal or inconclusive ultrastructure and 67% missing prior ultrastructure results., Conclusions: This study shows the added value of high-throughput targeted NGS in expediting PCD diagnosis. Therefore, there is potential significant patient benefit in wider and/or earlier implementation of genetic screening., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

This article describes the history of the diagnostic class of neurodevelopmental disorders (NDDs) up to DSM-5. We further analyze how the development of genetics will transform the classification and diagnosis of NDDs. In DSM-5, NDDs include intellectual disability (ID), autism spectrum disorder (ASD), and attention-deficit/hyperactivity disorder (ADHD). Physicians in German-, French- and English-speaking countries (eg, Weikard, Georget, Esquirol, Down, Asperger, and Kanner) contributed to the phenomenological definitions of these disorders throughout the 18th and 20th centuries. These diagnostic categories show considerable comorbidity and phenotypic overlap. NDDs are one of the chapters of psychiatric nosology most likely to benefit from the approach advocated by the National Institute of Mental Health's Research Domain Criteria project. Genetic research supports the hypothesis that ID, ASD, ADHD, schizophrenia, and bipolar disorder lie on a neurodevelopmental continuum. The identification of recurrently observed copy number variants and disruptive gene variants in ASD (eg, CDH8, 16p11.2, SCN2A) led to the adoption of the genotype-first approach to characterize individuals at the etiological level.
., (© 2019, AICHServier GroupCopyright © 2019 AICH Servier Group. All rights reserved.)

Hydrocephalus is one of the most prevalent form of developmental central nervous system (CNS) malformations. Cerebrospinal fluid (CSF) flow depends on both heartbeat and body movement. Furthermore, it has been shown that CSF flow within and across brain ventricles depends on cilia motility of the ependymal cells lining the brain ventricles, which play a crucial role to maintain patency of the narrow sites of CSF passage during brain formation in mice. Using whole-exome and whole-genome sequencing, we identified an autosomal-dominant cause of a distinct motile ciliopathy related to defective ciliogenesis of the ependymal cilia in six individuals. Heterozygous de novo mutations in FOXJ1, which encodes a well-known member of the forkhead transcription factors important for ciliogenesis of motile cilia, cause a motile ciliopathy that is characterized by hydrocephalus internus, chronic destructive airway disease, and randomization of left/right body asymmetry. Mutant respiratory epithelial cells are unable to generate a fluid flow and exhibit a reduced number of cilia per cell, as documented by high-speed video microscopy (HVMA), transmission electron microscopy (TEM), and immunofluorescence analysis (IF). TEM and IF demonstrate mislocalized basal bodies. In line with this finding, the focal adhesion protein PTK2 displays aberrant localization in the cytoplasm of the mutant respiratory epithelial cells., (Copyright © 2019 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Lung cancer is the leading cause of cancer-related deaths in the world. The most prevalent subtype, accounting for 85% of cases, is non-small-cell lung cancer (NSCLC). Lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD) are the most common subtypes. Despite recent advances in treatment, the low 5-year survival rate of NSCLC patients (approximately 13%) reflects the lack of early diagnostic biomarkers and incomplete understanding of the underlying disease mechanisms. We hypothesized that integration of metabolomic, transcriptomic and genetic profiles of tumours and matched normal tissues could help to identify important factors and potential therapeutic targets that contribute to tumorigenesis. We integrated omics profiles in tumours and matched adjacent normal tissues of patients with LUSC (N = 20) and LUAD (N = 17) using multiple system biology approaches. We confirmed the presence of previously described metabolic pathways in NSCLC, particularly those mediating the Warburg effect. In addition, through our combined omics analyses we found that metabolites and genes that contribute to haemostasis, angiogenesis, platelet activation and cell proliferation were predominant in both subtypes of NSCLC. The important roles of adenosine diphosphate in promoting cancer metastasis through platelet activation and angiogenesis suggest this metabolite could be a potential therapeutic target., (© 2019 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.)

Purpose: Internationally adopted variant interpretation guidelines from the American College of Medical Genetics and Genomics (ACMG) are generic and require disease-specific refinement. Here we developed CardioClassifier ( http://www.cardioclassifier.org ), a semiautomated decision-support tool for inherited cardiac conditions (ICCs)., Methods: CardioClassifier integrates data retrieved from multiple sources with user-input case-specific information, through an interactive interface, to support variant interpretation. Combining disease- and gene-specific knowledge with variant observations in large cohorts of cases and controls, we refined 14 computational ACMG criteria and created three ICC-specific rules., Results: We benchmarked CardioClassifier on 57 expertly curated variants and show full retrieval of all computational data, concordantly activating 87.3% of rules. A generic annotation tool identified fewer than half as many clinically actionable variants (64/219 vs. 156/219, Fisher's P = 1.1  ×  10 -18 ), with important false positives, illustrating the critical importance of disease and gene-specific annotations. CardioClassifier identified putatively disease-causing variants in 33.7% of 327 cardiomyopathy cases, comparable with leading ICC laboratories. Through addition of manually curated data, variants found in over 40% of cardiomyopathy cases are fully annotated, without requiring additional user-input data., Conclusion: CardioClassifier is an ICC-specific decision-support tool that integrates expertly curated computational annotations with case-specific data to generate fast, reproducible, and interactive variant pathogenicity reports, according to best practice guidelines.

The enormous successes in the genetics and genomics of many diseases have provided the basis for the advancement of precision medicine. Thus, the detection of genetic variants associated with neuropsychiatric disorders, as well as treatment outcome, has raised growing expectations that these findings could soon be translated into the clinic to improve diagnosis, the prediction of disease risk and individual response to drug therapy. In this article, we will provide an introduction to the search for genes involved in psychiatric illness and summarize the present findings in major psychiatric disorders. We will review the genetic variants in genes encoding drug metabolizing enzymes and specific drug targets which were found to be associated with variable drug response and severe side effects. We will evaluate the clinical translatability of these findings, whether there is currently any role for genetic testing and in this context, make valuable sources of information available to the clinician seeking guidance and advice in this rapidly developing field of psychiatric genetics.

Background: Patients with LIS1-associated classic lissencephaly typically present with severe psychomotor retardation and drug-resistant epilepsy within the first year., Aim: To analyze the epileptogenic phenotype and response to antiepileptic therapy in LIS1-associated classic lissencephaly., Method: Retrospective evaluation of 22 patients (8 months-24 years) with genetically and radiologically confirmed LIS1-associated classic lissencephaly in 16 study centers., Results: All patients in our cohort developed drug-resistant epilepsy. In 82% onset of seizures was noted within the first six months of life, most frequently with infantile spasms. Later in infancy the epileptogentic phenotype became more variable and included different forms of focal seizures as well generalized as tonic-clonic seizures, with generalized tonic-clonic seizures being the predominant type. Lamotrigine and valproate were rated most successful with good or partial response rates in 88-100% of the patients. Both were evaluated significantly better than levetiracetam (p<0.05) and sulthiame (p<0.01) in the neuropediatric assessment and better than levetiracetam, sulthiame (p<0.05) and topiramate (p<0.01) in the family survey. Phenobarbital and vigabatrin achieved good or partial response in 62-83% of the patients., Conclusion: Our findings suggest that patients with LIS1-associated lissencephaly might benefit most from lamotrigine, valproate, vigabatrin or phenobarbital., (Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

NF-κB essential modulator (NEMO) deficiency causes ectodermal dysplasia with immunodeficiency in males, while manifesting as incontinentia pigmenti in heterozygous females. We report a family with NEMO deficiency, in which a female carrier displayed skewed X-inactivation favoring the mutant NEMO allele associated with symptoms of Behçet's disease. Hematopoietic stem cell transplantation of an affected boy from this donor reconstituted an immune system with retained skewed X-inactivation. After transplantation no more severe infections occurred, indicating that an active wild-type NEMO allele in only 10% of immune cells restores host defense. Yet he developed inflammatory bowel disease (IBD). While gut infiltrating immune cells stained strongly for nuclear p65 indicating restored NEMO function, this was not the case in intestinal epithelial cells - in contrast to cells from conventional IBD patients. These results extend murine observations that epithelial NEMO-deficiency suffices to cause IBD. High anti-TNF doses controlled the intestinal inflammation and symptoms of Behçet's disease., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Biallelic mutations of ALS2 cause a clinical spectrum of overlapping autosomal recessive neurodegenerative disorders: infantile-onset ascending hereditary spastic paralysis (IAHSP), juvenile primary lateral sclerosis (JPLS), and juvenile amyotrophic lateral sclerosis (ALS2). We report on eleven individuals affected with IAHSP from two consanguineous Pakistani families. A combination of linkage analysis with homozygosity mapping and targeted sequencing identified two novel ALS2 mutations, a c.194T > C (p.Phe65Ser) missense substitution located in the first RCC-like domain of ALS2/alsin and a c.2998delA (p.Ile1000*) nonsense mutation. This study of extended families including a total of eleven affected individuals suggests that a given ALS2 mutation may lead to a phenotype with remarkable intrafamilial clinical homogeneity.

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is a recently discovered rare disease caused by gain-of-function mutations of the V2 vasopressin receptor gene, AVPR2. To date, mutations of Phe229 and Arg137 have been identified as gain-of-function in the V2 vasopressin receptor (V2R). These receptor mutations lead to hyponatremia, which may lead to clinical symptoms in infants. Here we present a newly identified I130N substitution in exon 2 of the V2R gene in a family, causing NSIAD. This I130N mutation resulted in constitutive activity of the V2R with constitutive cyclic adenosine monophosphate (cAMP) generation in HEK293 cells. This basal activity could be blocked by the inverse agonist tolvaptan and arginine-vasopressin stimulation enhanced the cAMP production of I130N-V2R. The mutation causes a biased receptor conformation as the basal cAMP generation activity of I130N does not lead to interaction with β-arrestin. The constitutive activity of the mutant receptor caused constitutive dynamin-dependent and β-arrestin-independent internalization. The inhibition of basal internalization using dominant-negative dynamin resulted in an increased cell surface expression. In contrast to the constitutive internalization, agonist-induced endocytosis was β-arrestin dependent. Thus, tolvaptan could be used for treatment of hyponatremia in patients with NSIAD who carry the I130N-V2R mutation.

The impact that next-generation sequencing technology (NGS) is having on many aspects of molecular and cell biology, is becoming increasingly apparent. One of the most noticeable outcomes of the new technology in human genetics, has been the accelerated rate of identification of disease-causing genes. Especially for rare, heterogeneous disorders, such as autosomal recessive primary microcephaly (MCPH), the handful of genes previously known to harbour disease-causing mutations, has grown at an unprecedented rate within a few years. Knowledge of new genes mutated in MCPH over the last four years has contributed to our understanding of the disorder at both the clinical and cellular levels. The functions of proteins such as WDR62, CASC5, PHC1, CDK6, CENP-E, CENP-F, CEP63, ZNF335, PLK4 and TUBGPC, have been added to the complex network of critical cellular processes known to be involved in brain growth and size. In addition to the importance of mitotic spindle assembly and structure, centrosome and centriole function and DNA repair and damage response, new mechanisms involving kinetochore-associated proteins and chromatin remodelling complexes have been elucidated. Two of the major contributions to our clinical knowledge are the realisation that primary microcephaly caused by mutations in genes at the MCPH loci is seldom an isolated clinical feature and is often accompanied either by additional cortical malformations or primordial dwarfism. Gene-phenotype correlations are being revisited, with a new dimension of locus heterogeneity and phenotypic variability being revealed., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Holoprosencephaly is a clinically and genetically heterogeneous midline brain malformation associated with neurologic manifestations including developmental delay, intellectual disability and seizures. Although mutations in the sonic hedgehog gene SHH and more than 10 other genes are known to cause holoprosencephaly, many patients remain without a molecular diagnosis. Here we show that a homozygous truncating mutation of STIL not only causes severe autosomal recessive microcephaly, but also lobar holoprosencephaly in an extended consanguineous Pakistani family. STIL mutations have previously been linked to centrosomal defects in primary microcephaly at the MCPH7 locus. Our results thus expand the clinical phenotypes associated with biallellic STIL mutations to include holoprosencephaly.

Warburg Micro Syndrome (WARBM, MIM 600118) is a rare, severe autosomal recessive neurodevelopmental disorder characterized by microcephaly, microphthalmia, microcornea, congenital cataract, cortical dysplasia, corpus callosum hypoplasia, intellectual disability, hypotonia and hypogonadism. RABS, small G proteins belonging to the RAS superfamily, are master regulators of vesicle trafficking in the cell. The identification of mutations in the RAB3GAP1 and RAB3GAP2 genes, which together encode the RAB3GTPase-activating protein, a key regulator in calcium-mediated exocytosis of neurotransmitters and hormones, has underpinned abnormal development of the brain, eye and genitalia as cardinal features of this syndrome. More than 100 patients have been reported with WARBM, with mutations in the RABGAP1, RABGAP2, RAB18 and TBC1D20 genes. The objective of the study was to describe the recurrent RAB3GAP1 mutations and compare the clinical features of the patients with WARBM in the Turkish population. Here we report two brothers with Warburg Micro Syndrome 1 from a non-consanguineous Turkish family with clinical features similar to those previously reported in Turkish patients with RAB3GAP1 mutations. We found that the c.748+1G>A splice-site mutation in RAB3GAP1 intron 8 is common and has so far only been detected in patients of Turkish ethnic origin. Although one of our patients has a distal extra crease on the 4th finger and another has nephrolithiasis, there does not appear to be any specific phenotypic findings associated with this mutation.

Mutations in WDR62 are associated with primary microcephaly; however, they have been reported with wide phenotypic variability. We report on six individuals with novel WDR62 mutations who illustrate this variability and describe three in greater detail. Of the three, one lacks neuromotor development and has severe pachygyria on MRI, another has only delayed speech and motor development and moderate polymicrogyria, and the third has an intermediate phenotype. We observed a rare copy number change of unknown significance, a 17q25qter duplication, in the first severely affected individual. The 17q25 duplication included an interesting candidate gene, tubulin cofactor D (TBCD), crucial in microtubule assembly and disassembly. Sequencing of the non-duplicated allele showed a TBCD missense mutation, predicted to cause a deleterious p.Phe1121Val substitution. Sequencing of a cohort of five patients with WDR62 mutations, including one with an identical mutation and different phenotype, plus 12 individuals with diagnosis of microlissencephaly and another individual with mild intellectual disability (ID) and a 17q25 duplication, did not reveal TBCD mutations. However, immunostaining with tubulin antibodies of cells from patients with both WDR62 and TBCD mutation showed abnormal tubulin network when compared to controls and cells with only the WDR62 mutation. Therefore, we propose that genetic factors contribute to modify the severity of the WDR62 phenotype and, although based on suggestive evidence, TBCD could function as one of such factors., (© 2014 Wiley Periodicals, Inc.)

Alpha-dystroglycanopathies form a genetically heterogeneous group of congenital muscular dystrophies with a large variety of clinical phenotypes. Within this group mutations in the protein O-mannosyltransferase genes (POMT1 and POMT2) are known to cause a spectrum of CMD disorders including the Walker-Warburg Syndrome with severe brain and ocular malformations, and the limb girdle muscular dystrophy with and without mental retardation. In this case report the clinical phenotype and brain and muscle MRI findings of two siblings of 10 and 7years (male/female) homozygous for a novel mutation in the POMT1 gene (c.2220G>C, p.Trp740Cys) and a 10year old boy with two novel mutations in the POMT2 gene ((c.215G>A, p.Arg72His) and (c.713G>T, p.Gly238Val) are presented. Mutation detection was performed by direct sequencing of the FKRP, FKTN, POMT1 and POMT2 genes. T1-weighted axial muscle MRI of the lower limbs revealed diffuse fatty degeneration of thigh and calf muscles with predominance of gluteus maximus, adductor magnus, posterior thigh, medial gastrocnemius, and peroneus muscles, but no edematous changes. As a similar pattern of muscle involvement had been described in FKRP related α-dystroglycanopathy LGMD2I, we conclude that α-dystroglycanopathies may present with distinctive muscle MRI changes., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: In term newborns meconium ileus is frequently associated with cystic fibrosis. Reports on meconium ileus in preterm infants being diagnosed with cystic fibrosis early after birth are very scarce. Associations between genotype and phenotype in cystic fibrosis and its particular comorbidities have been reported., Case Presentation: Two extremely preterm twin infants (26 weeks of gestation) born from a Malaysian mother and a Caucasian father were presented with typical signs of meconium ileus. Despite immediate surgery both displayed a unique and finally lethal course. Mutation analysis revealed a novel, probably pathogenic cystic fibrosis mutation, p.Cys524Tyr. The novel mutation might explain the severity of disease next to typical sequelae of prematurity., Conclusion: Preterm neonates with meconium ileus have to be evaluated for cystic fibrosis beyond ethnical boundaries, but may take devastating clinical courses despite early treatment. The novel, potentially pathogenic CF mutation p.Cys524Tyr might be associated with severe meconium ileus in neonates. Disease-modifying loci are important targets for intestinal comorbidity of cystic fibrosis.

blind sterile (bs) is a spontaneous autosomal-recessive mouse mutation discovered more than 30 years ago. Phenotypically, bs mice exhibit nuclear cataracts and male infertility; genetic analyses assigned the bs locus to mouse chromosome 2. In this study, we first positionally cloned the bs locus and identified a putative causative mutation in the Tbc1d20 gene. Functional analysis established the mouse TBC1D20 protein as a GTPase-activating protein (GAP) for RAB1 and RAB2, and bs as a TBC1D20 loss-of-function mutation. Evaluation of bs mouse embryonic fibroblasts (mEFs) identified enlarged Golgi morphology and aberrant lipid droplet (LD) formation. Based on the function of TBC1D20 as a RABGAP and the bs cataract and testicular phenotypes, we hypothesized that mutations in TBC1D20 may contribute to Warburg micro syndrome (WARBM); WARBM constitutes a spectrum of disorders characterized by eye, brain, and endocrine abnormalities caused by mutations in RAB3GAP1, RAB3GAP2, and RAB18. Sequence analysis of a cohort of 77 families affected by WARBM identified five distinct TBC1D20 loss-of-function mutations, thereby establishing these mutations as causative of WARBM. Evaluation of human fibroblasts deficient in TBC1D20 function identified aberrant LDs similar to those identified in the bs mEFs. Additionally, our results show that human fibroblasts deficient in RAB18 and RAB3GAP1 function also exhibit aberrant LD formation. These findings collectively indicate that a defect in LD formation/metabolism may be a common cellular abnormality associated with WARBM, although it remains unclear whether abnormalities in LD metabolism are contributing to WARBM disease pathology., (Copyright © 2013 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Polydypsia and polyuria are frequent symptoms in patients with sellar masses caused by neurohypophyseal diabetes insipidus. Autosomal dominant familial neurohypophyseal diabetes insipidus (adFNDI), a disorder caused by mutations in the arginine vasopressin (AVP) -neurophysin II (NPII) gene, should be considered as a rare differential diagnosis. A delayed diagnosis bears the risk of life-threatening electrolyte imbalances and permanent urinary tract damage, leading to impaired quality of life.We present a Caucasian kindred of at least 4 generations with FNDI.Clinical histories, endocrine para-meters, and results of molecular analyses of the AVP gene are presented with a review of the literature on diabetes insipidus (DI) related urinary tract dilatation.Polyuria and polydipsia were only reported based on explicit and thorough interrogation after more than 4 years of clinical follow-up. A novel heterozygous mutation in the AVP gene was found in all examined symptomatic subjects (c.1-33&#95;c.4del37nt). A literature review revealed that non-obstructive hydronephrosis (NOH) is a rare but known complication of DI.Since increased fluid intake is often a typical familial pattern in adFNDI, it is frequently missed as being pathologic in affected patients, therefore a detailed clinical history of drinking volumes is of critical importance. AVP gene testing is an important component in the confirmation of the diagnosis. Otherwise unexplainable NOH should lead to further investigations and evaluation of rare diseases like FNDI., (© Georg Thieme Verlag KG Stuttgart · New York.)

5q14.3 deletions spanning and flanking MEF2C as well as intragenic MEF2C mutations have recently been described as a cause of severe intellectual disability, epilepsy, and muscular hypotonia, with variable brain and other anomalies. With an increasing number of patients described, the clinical presentation of the patients appears to be relatively uniform, however the structural brain phenotypes described are variable. We describe two unrelated patients with overlapping de novo interstitial deletions of 4.1 and 1.9 Mb, including MEF2C in 5q14.3, one of whom had a complex brain malformation which could be best described as microcephaly with simplified gyral pattern (MSG). Expression analysis in both patients confirmed haploinsufficiency for MEF2C, decreased MECP2 expression and increased C3ORF58 (DIA1) expression, which is a new finding. A detailed analysis of brain and white matter abnormalities reported in patients with 5q14.3 deletion syndrome to date revealed a greater number of reported abnormalities in patients with deletions not including MEF2C than those with deletions or mutations directly affecting MEF2C. Screening an additional 43 patients with malformations of cerebral cortical development (MCD) for mutations in MEF2C and/or deletions in 5q14.3q15, did not detect any additional mutations, allowing us to conclude that 5q14.3 deletion syndrome is a rare cause of microcephaly with simplified gyral pattern., (Copyright © 2013 Wiley Periodicals, Inc.)

Microcephaly-capillary malformation (MIC-CAP) syndrome is characterized by severe microcephaly with progressive cortical atrophy, intractable epilepsy, profound developmental delay and multiple small capillary malformations on the skin. We used whole-exome sequencing of five patients with MIC-CAP syndrome and identified recessive mutations in STAMBP, a gene encoding the deubiquitinating (DUB) isopeptidase STAMBP (STAM-binding protein, also known as AMSH, associated molecule with the SH3 domain of STAM) that has a key role in cell surface receptor-mediated endocytosis and sorting. Patient cell lines showed reduced STAMBP expression associated with accumulation of ubiquitin-conjugated protein aggregates, elevated apoptosis and insensitive activation of the RAS-MAPK and PI3K-AKT-mTOR pathways. The latter cellular phenotype is notable considering the established connection between these pathways and their association with vascular and capillary malformations. Furthermore, our findings of a congenital human disorder caused by a defective DUB protein that functions in endocytosis implicates ubiquitin-conjugate aggregation and elevated apoptosis as factors potentially influencing the progressive neuronal loss underlying MIC-CAP syndrome.

Warburg Micro syndrome and Martsolf syndrome (MS) are heterogeneous autosomal-recessive developmental disorders characterized by brain, eye, and endocrine abnormalities. Causative biallelic germline mutations have been identified in RAB3GAP1, RAB3GAP2, or RAB18, each of which encode proteins involved in membrane trafficking. This report provides an up to date overview of all known disease variants identified in 29 previously published families and 52 new families. One-hundred and forty-four Micro and nine Martsolf families were investigated, identifying mutations in RAB3GAP1 in 41% of cases, mutations in RAB3GAP2 in 7% of cases, and mutations in RAB18 in 5% of cases. These are listed in Leiden Open source Variation Databases, which was created by us for all three genes. Genotype-phenotype correlations for these genes have now established that the clinical phenotypes in Micro syndrome and MS represent a phenotypic continuum related to the nature and severity of the mutations present in the disease genes, with more deleterious mutations causing Micro syndrome and milder mutations causing MS. RAB18 has not yet been linked to the RAB3 pathways, but mutations in all three genes cause an indistinguishable phenotype, making it likely that there is some overlap. There is considerable genetic heterogeneity for these disorders and further gene identification will help delineate these pathways., (© 2013 Wiley Periodicals, Inc.)

Background: Primary autosomal recessive microcephaly (MCPH) is a rare neurodevelopmental disorder that results in severe microcephaly at birth with pronounced reduction in brain volume, particularly of the neocortex, simplified cortical gyration and intellectual disability. Homozygous mutations in the Cyclin-dependent kinase 5 regulatory subunit-associated protein 2 gene CDK5RAP2 are the cause of MCPH3. Despite considerable interest in MCPH as a model disorder for brain development, the underlying pathomechanism has not been definitively established and only four pedigrees with three CDK5RAP2 mutations have been reported. Specifically for MCPH3, no detailed radiological or histological descriptions exist., Methods/results: We sought to characterize the clinical and radiological features and pathological cellular processes that contribute to the human MCPH3 phenotype. Haplotype analysis using microsatellite markers around the MCPH1-7 and PNKP loci in an Italian family with two sons with primary microcephaly, revealed possible linkage to the MCPH3 locus. Sequencing of the coding exons and exon/intron splice junctions of the CDK5RAP2 gene identified homozygosity for the novel nonsense mutation, c.4441C > T (p.Arg1481*), in both affected sons. cMRI showed microcephaly, simplified gyral pattern and hypogenesis of the corpus callosum. The cellular phenotype was assessed in EBV-transformed lymphocyte cell lines established from the two affected sons and compared with healthy male controls. CDK5RAP2 protein levels were below detection level in immortalized lymphocytes from the patients. Moreover, mitotic spindle defects and disrupted γ-tubulin localization to the centrosome were apparent., Conclusion: These results suggest that spindle defects and a disruption of centrosome integrity play an important role in the development of microcephaly in MCPH3.

OFD1, now recognized as a ciliopathy, is characterized by malformations of the face, oral cavity and digits, and is transmitted as an X-linked condition with lethality in males. Mutations in OFD1 also cause X-linked Joubert syndrome (JBTS10) and Simpson-Golabi-Behmel syndrome type 2 (SGBS2). We have studied 55 sporadic and six familial cases of suspected OFD1. Comprehensive mutation analysis in OFD1 revealed mutations in 37 female patients from 30 families; 22 mutations have not been previously described including two heterozygous deletions spanning OFD1 and neighbouring genes. Analysis of clinical findings in patients with mutations revealed that oral features are the most reliable diagnostic criteria. A first, detailed evaluation of brain MRIs from seven patients with cognitive defects illustrated extensive variability with the complete brain phenotype consisting of complete agenesis of the corpus callosum, large single or multiple interhemispheric cysts, striking cortical infolding of gyri, ventriculomegaly, mild molar tooth malformation and moderate to severe cerebellar vermis hypoplasia. Although the OFD1 gene apparently escapes X-inactivation, skewed inactivation was observed in seven of 14 patients. The direction of skewing did not correlate with disease severity, reinforcing the hypothesis that additional factors contribute to the extensive intrafamilial variability., (© 2012 Wiley Periodicals, Inc.)

The spectrum of lissencephaly ranges from absent (agyria) or decreased (pachygyria) convolutions to less severe malformation known as subcortical band heterotopia. Mutations involving LIS1 and TUBA1A result in the classic form of lissencephaly, whereas mutations of the DCX gene cause lissencephaly in males and subcortical band heterotopia in females. This report describes the clinical manifestations and imaging and genetic findings in 2 boys with lissencephaly and a girl with subcortical band heterotopia. An ovel mutation (c.83&#95;84delAT, p.Tyr28Phefs*31) was identified in LIS1 in 1 of the boys with lissencephaly and another novel mutation (c.200delG, p.Ile68Leufs*87) was found in DCX in the girl with subcortical band heterotopia. The mutations appeared in the first half of the genes and are predicted to result in truncated proteins. A mutation was found in the TUBA1A gene (c.1205G>A, p.Arg402His) in the other boy. This mutation affects the folding of tubulin heterodimers, changing the interactions with proteins that bind microtubules.

Background: Submicroscopic deletions in 14q12 spanning FOXG1 or intragenic mutations have been reported in patients with a developmental disorder described as a congenital variant of Rett syndrome. This study aimed to further characterise and delineate the phenotype of FOXG1 mutation positive patients., Method: The study mapped the breakpoints of a 2;14 translocation by fluorescence in situ hybridisation and analysed three chromosome rearrangements in 14q12 by cytogenetic analysis and/or array comparative genomic hybridisation. The FOXG1 gene was sequenced in 210 patients, including 129 patients with unexplained developmental disorders and 81 MECP2 mutation negative individuals., Results: One known mutation, seen in two patients, and nine novel mutations of FOXG1 including two deletions, two chromosome rearrangements disrupting or displacing putative cis-regulatory elements from FOXG1, and seven sequence changes, are reported. Analysis of 11 patients in this study, and a further 15 patients reported in the literature, demonstrates a complex constellation of features including mild postnatal growth deficiency, severe postnatal microcephaly, severe mental retardation with absent language development, deficient social reciprocity resembling autism, combined stereotypies and frank dyskinesias, epilepsy, poor sleep patterns, irritability in infancy, unexplained episodes of crying, recurrent aspiration, and gastro-oesophageal reflux. Brain imaging studies reveal simplified gyral pattern and reduced white matter volume in the frontal lobes, corpus callosum hypogenesis, and variable mild frontal pachgyria., Conclusions: These findings have significantly expanded the number of FOXG1 mutations and identified two affecting possible cis-regulatory elements. While the phenotype of the patients overlaps both classic and congenital Rett syndrome, extensive clinical evaluation demonstrates a distinctive and clinically recognisable phenotype which the authors suggest designating as the FOXG1 syndrome.

Six genes including POMT1, POMT2, POMGNT1, FKRP, Fukutin (FKTN) and LARGE encode proteins involved in the glycosylation of α-dystroglycan (α-DG). Abnormal glycosylation of α-DG is a common finding in Walker-Warburg syndrome (WWS), muscle-eye-brain disease (MEB), Fukuyama congenital muscular dystrophy (FCMD), congenital muscular dystrophy types 1C and 1D and some forms of autosomal recessive limb-girdle muscular dystrophy (LGMD2I, LGMD2K, LGMD2M), and is associated with mutations in the above genes. FCMD, caused by mutations in Fukutin (FKTN), is most frequent in Japan, but an increasing number of FKTN mutations are being reported outside of Japan. We describe four new patients with FKTN mutations and phenotypes ranging from: severe WWS in a Greek-Croatian patient, to congenital muscular dystrophy and cobblestone lissencephaly resembling MEB-FCMD in two Turkish patients, and limb-girdle muscular dystrophy and no mental retardation in a German patient. Four of the five different FKTN mutations have not been previously described., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Warburg Micro syndrome and Martsolf syndrome are clinically overlapping autosomal recessive conditions characterized by congenital cataracts, microphthalmia, postnatal microcephaly, and developmental delay. The neurodevelopmental and ophthalmological phenotype is more severe in Warburg Micro syndrome in which cerebral malformations and severe motor and mental retardation are common. While biallelic loss-of-function mutations in RAB3GAP1 are present in the majority of patients with Warburg Micro syndrome; a hypomorphic homozygous splicing mutation of RAB3GAP2 has been reported in a single family with Martsolf syndrome. Here, we report a novel homozygous RAB3GAP2 small in-frame deletion, c.499&#95;507delTTCTACACT (p.Phe167&#95;Thr169del) that causes Warburg Micro syndrome in a girl from a consanguineous Turkish family presenting with congenital cataracts, microphthalmia, absent visually evoked potentials, microcephaly, polymicrogyria, hypoplasia of the corpus callosum, and severe developmental delay. No RAB3GAP2 mutations were detected in ten additional unrelated patients with RAB3GAP1-negative Warburg Micro syndrome, consistent with further genetic heterogeneity. In conclusion, we provide evidence that RAB3GAP2 mutations are not specific to Martsolf syndrome. Rather, our findings suggest that loss-of-function mutations of RAB3GAP1 as well as functionally severe RAB3GAP2 mutations cause Warburg Micro syndrome while hypomorphic RAB3GAP2 mutations can result in the milder Martsolf phenotype. Thus, a phenotypic severity gradient may exist in the RAB3GAP-associated disease continuum (the "Warburg-Martsolf syndrome") which is presumably determined by the mutant gene and the nature of the mutation.

Warburg Micro Syndrome is a rare, autosomal recessive syndrome characterized by microcephaly, microphthalmia, microcornia, congenital cataracts, optic atrophy, cortical dysplasia, in particular corpus callosum hypoplasia, severe mental retardation, spastic diplegia, and hypogonadism. We have found five new mutations in the RAB3GAP1 gene in seven patients with suspected Micro Syndrome from families with Turkish, Palestinian, Danish, and Guatemalan backgrounds. A thorough clinical investigation of the patients has allowed the delineation of symptoms that are consistently present in the patients and may aid the differential diagnosis of Micro Syndrome for patients in the future. All patients had postnatal microcephaly, micropthalmia, microcornia, bilateral congenital cataracts, short palpebral fissures, optic atrophy, severe mental retardation, and congenital hypotonia with subsequent spasticity. Only one patient had microcephaly at birth, highlighting the fact that congenital microcephaly is not a consistent feature of Micro syndrome. Analysis of the brain magnetic resonance imagings (MRIs) revealed a consistent pattern of polymicrogyria in the frontal and parietal lobes, wide sylvian fissures, a thin hypoplastic corpus callosum, and increased subdural spaces. All patients were homozygous for the mutations detected and all mutations were predicted to result in a truncated RAB3GAP1 protein. The analysis of nine polymorphic markers flanking the RAB3GAP1 gene showed that the mutation c.1410C>A (p.Tyr470X), for which a Danish patient was homozygous, occurred on a haplotype that is shared by the unrelated heterozygous parents of the patient. This suggests a possible founder effect for this mutation in the Danish population.

The etiology of non-syndromic hydrocephalus is poorly understood. Via positional cloning in a consanguineous family with autosomal recessive hydrocephalus we have now identified a homozygous splice site mutation in the CCDC88C gene as a novel cause of a complex hydrocephalic brain malformation. The only living patient showed normal psychomotor development at the age of 3 years and 3 months and her deceased aunt, who was assumed to suffer from the same condition, had mild mental retardation. The mutation in the affected patients, a homozygous substitution in the donor splice site of intron 29, resulted in a shorter transcript due to exclusion of exon 29 and loss of functional protein, as shown by Western blotting (p.S1591HfsX7). In normal human tissue panels, we found CCDC88C ubiquitously expressed, but most prominently in the fetal brain, especially in pons and cerebellum, while expression in the adult brain appeared to be restricted to cortex and medulla oblongata. CCDC88C encodes DAPLE (HkRP2), a Hook-related protein with a binding domain for the central Wnt signalling pathway protein Dishevelled. Targeted quantitative RT-PCR and expression profiling of 84 genes from the Wnt signalling pathway in peripheral blood from the index patient and her healthy mother revealed increased mRNA levels of CCDC88C indicating transcriptional upregulation. Due to loss of CCDC88C function β-catenin (CTNNB1) and the downstream target LEF1 showed increased mRNA levels in the patient, but many genes from the Wnt pathway and transcriptional target genes showed reduced expression, which might be explained by a complex negative feedback loop. We have thus identified a further essential component of the Wnt signalling pathway in human brain development.

Mutations in the alpha-1a Tubulin (TUBA1A) gene have recently been found to cause cortical malformations resemblant of classical lissencephaly but with a specific combination of features. To date, TUBA1A mutations have been described in five patients and three foetuses. Our aims were to establish how common TUBA1A mutations are in patients with lissencephaly and to contribute to defining the phenotype associated with TUBA1A mutation. We performed mutation analysis in the TUBA1A gene in 46 patients with classical lissencephaly. In 44 of the patients, mutations in the LIS1 and/or DCX genes had previously been excluded; in 2 patients, mutation analysis was only performed in TUBA1A based on magnetic resonance imaging (MRI) findings. We identified three new mutations and one recurrent mutation in five patients with variable patterns of lissencephaly on brain MRI. Four of the five patients had congenital microcephaly, and all had dysgenesis of the corpus callosum and cerebellar hypoplasia, and variable cortical malformations, including subtle subcortical band heterotopia and absence or hypoplasia of the anterior limb of the internal capsule. We estimate the frequency of mutation in TUBA1A gene in patients with classical lissencephaly to be approximately 4%, and although not as common as mutations in the LIS1 or DCX genes, mutation analysis in TUBA1A should be included in the molecular genetic diagnosis of classical lissencephaly, particularly in patients with the combination of features highlighted in this paper.

FG syndrome was originally described as a rare syndromic cause of X-linked mental retardation associated with congenital heart disease, anal atresia, inguinal hernia, cryptorchidism, and other anomalies. However, recent reports have highlighted the more common milder presentation which has for cardinal features developmental delay, particularly in speech, neonatal hypotonia, relative macrocephaly, dysmorphic facial features, severe constipation, and few if any congenital malformations. Thus far, five separate loci have been identified on the X chromosome but attempts at finding the responsible gene have not yet been successful. Given that one putative FG locus (FGS2) is situated at Xq28, which is the location of the Filamin A gene (FLNA), and that a Filamin A mutation was reported in a boy with facial dysmorphism and constipation, it was hypothesized that Filamin A mutations could be one cause of FG syndrome. Indeed, a previously unreported FLNA missense mutation (P1291L) was detected in our patient with FG syndrome, thus supporting this hypothesis and indicating that FG syndrome could now be added to the list of Filamin A-related disorders. Filamin A studies in other children with FG syndrome would help to confirm this association., ((c) 2007 Wiley-Liss, Inc.)

Background: Lissencephaly is a neuronal migration disorder leading to absent or reduced gyration and a broadened but poorly organized cortex. The most common form of lissencephaly is isolated, referred as classic or type 1 lissencephaly. Type 1 lissencephaly is mostly associated with a heterozygous deletion of the entire LIS1 gene, whereas intragenic heterozygous LIS1 mutations or hemizygous DCX mutations in males are less common., Methods: Eighteen unrelated patients with type 1 lissencephaly were clinically and genetically assessed. In addition, patients with subcortical band heterotopia (n = 1) or lissencephaly with cerebellar hypoplasia (n = 2) were included., Results: Fourteen new and seven previously described LIS1 mutations were identified. We observed nine truncating mutations (nonsense, n = 2; frameshift, n = 7), six splice site mutations, five missense mutations, and one in-frame deletion. Somatic mosaicism was assumed in three patients with partial subcortical band heterotopia in the occipital-parietal lobes or mild pachygyria. We report three mutations in exon 11, including a frameshift which extends the LIS1 protein, leading to type 1 lissencephaly and illustrating the functional importance of the WD domains at the C terminus. Furthermore, we present two patients with novel LIS1 mutations in exon 10 associated with lissencephaly with cerebellar hypoplasia type a., Conclusion: In contrast to previous reports, our data suggest that neither type nor position of intragenic mutations in the LIS1 gene allows an unambiguous prediction of the phenotypic severity. Furthermore, patients presenting with mild cerebral malformations such as subcortical band heterotopia or cerebellar hypoplasia should be considered for genetic analysis of the LIS1 gene.

Objectives: To present a family in which it was possible to perform prenatal diagnosis for the recessively inherited muscle-eye-brain disease (MEB) using linkage analysis., Methods: Linkage analysis and direct sequencing of the POMGNT1 gene were carried out in a Turkish MEB family with one affected individual. Fetal DNA was obtained from an ongoing pregnancy by chorionic villus sampling (CVS)., Results: Both linkage analysis of the POMGNT1/1p32-p34 region and direct sequencing for the novel familial mutation (R605H) demonstrated that the fetus did not have MEB., Conclusion: We report the first case of prenatal diagnosis in MEB by molecular genetic analysis., (Copyright 2007 John Wiley & Sons, Ltd.)

The effect of variation in genes coding for drug targets and for the enzymes involved in drug metabolism has highlighted the genetic component of drug response. Drug response can be likened to a complex, multifactorial genetic trait, and the study of its genetic variation, termed pharmacogenetics, is analogous to the study of complex genetic disease in terms of the questions posed and the analytical possibilities. Just as DNA variants are associated with specific disease predispositions, so will they be associated with individual response to certain drugs. The testing for drug response is following the same route as the genetic testing for inherited disorders, and has reached the stage where genome-wide analysis, as opposed to the analysis of single genes, is a reality. In this article, we will discuss some of the technical advances that facilitate such analyses, leading to faster and more extensive diagnostic capabilities.