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The standard-of-care (SOC) diagnostic prenatal testing includes a combination of cytogenetic methods such as karyotyping, fluorescence in situ hybridization (FISH), and chromosomal microarray (CMA) using either direct or cultured amniocytes or chorionic villi sampling (CVS). However, each technology has its limitations: karyotyping has a low resolution (>5Mb), FISH is targeted, and CMA does not detect balanced structural variants (SVs) or decipher complex rearrangements in the genome. These limitations necessitate the use of multiple tests, either simultaneously or sequentially to reach a genetic diagnosis. This long-standing prenatal testing workflow demonstrates the need for an alternative technology that can provide high-resolution results in a cost and time-effective manner. Optical genome mapping (OGM) is an emerging technology that has demonstrated its ability to detect all classes of SVs, including copy number variations (CNVs) and balanced abnormalities in a single assay, but has not been evaluated in the prenatal setting. This retrospective validation study analyzed 114 samples (including replicates), representing 94 unique and well-characterized samples that were received in our laboratory for traditional cytogenetic analysis with karyotyping, FISH, and/or CMA. Samples comprised 84 cultured amniocytes, and 10 phenotypically normal and cytogenetically negative controls. Six samples were run in triplicate to evaluate intra-run, inter-run, and inter-instrument reproducibility. Clinically relevant SVs and CNVs were reported using the Bionano Access software with standardized and built-in filtration criteria and phenotype-specific analysis. OGM was 100% concordant in identifying the 101 aberrations that included 29 interstitial/terminal deletions, 28 duplications, 26 aneuploidies, 6 absence of heterozygosity (AOH), 3 triploid genomes, 4 Isochromosomes, 1 translocation, and revealed the identity of 3 marker chromosomes, and 1 chromosome with additional material not determined by karyotyping. Additionally, OGM detected 64 additional clinically reportable SVs in 43 samples. OGM demonstrated high technical and analytical robustness and a limit of detection of 5% allele fraction for interstitial deletions and duplications, and 10% allele fraction for translocation and aneuploidy. This study demonstrates that OGM has the potential to identify unique genomic abnormalities such as CNVs, AOHs, and several classes of SVs including complex structural rearrangements. OGM has a standardized laboratory workflow and reporting solution that can be adopted in routine clinical laboratories and demonstrates the potential to replace the current SOC methods for prenatal diagnostic testing. We recommend its use as a first-tier genetic diagnostic test in a prenatal setting.

The standard-of-care (SOC) for genomic testing of myeloid cancers primarily relies on karyotyping/fluorescent in situ hybridization (FISH) (cytogenetic analysis) and targeted gene panels (usually ≤54 genes) that harbor hotspot pathogenic variants (molecular genetic analysis). Despite this combinatorial approach, ~50% of myeloid cancer genomes remain cytogenetically normal, and the limited sequencing variant profiles obtained from targeted panels are unable to resolve the molecular etiology of many myeloid tumors. In this study, we evaluated the performance and clinical utility of combinatorial use of optical genome mapping (OGM) and a 523-gene next-generation sequencing (NGS) panel for comprehensive genomic profiling of 30 myeloid tumors and compared it to SOC cytogenetic methods (karyotyping and FISH) and a 54-gene NGS panel. OGM and the 523-gene NGS panel had an analytical concordance of 100% with karyotyping, FISH, and the 54-gene panel, respectively. Importantly, the IPSS-R cytogenetic risk group changed from very good/good to very poor in 22% of MDS (2/9) cases based on comprehensive profiling (karyotyping, FISH, and 54-gene panel vs. OGM and 523-gene panel), while additionally identifying six compound heterozygous events of potential clinical relevance in six cases (6/30, 20%). This cost-effective approach of using OGM and a 523-gene NGS panel for comprehensive genomic profiling of myeloid cancers demonstrated increased yield of actionable targets that can potentially result in improved clinical outcomes.

An expanding range of genetic syndromes are characterized by genome-wide disruptions in DNA methylation profiles referred to as episignatures. Episignatures are distinct, highly sensitive and specific biomarkers that have recently been applied in clinical diagnosis of genetic syndromes. Episignatures are contained within the broader disorder-specific genome-wide DNA methylation changes which can share significant overlap amongst different conditions. In this study we performed functional genomic assessment and comparison of disorder-specific and overlapping genome-wide DNA methylation changes related to 65 genetic syndromes with previously described episignatures. We demonstrate evidence of disorder-specific and recurring genome-wide differentially methylated probes (DMPs) and regions (DMRs). The overall distribution of DMPs and DMRs across the majority of the neurodevelopmental genetic syndromes analyzed showed substantial enrichment in gene promoters and CpG islands, and under-representation of the more variable intergenic regions. Analysis showed significant enrichment of the DMPs and DMRs in gene pathways and processes related to neurodevelopment, including neurogenesis, synaptic signaling and synaptic transmission. This study expands beyond the diagnostic utility of DNA methylation episignatures by demonstrating correlation between the function of the mutated genes and the consequent genomic DNA methylation profiles as a key functional element in the molecular etiology of genetic neurodevelopmental disorders. This article is protected by copyright. All rights reserved.

The course of 187 individuals ages 3–21 years with Autistic Disorder was traced through a period of 20 years (enrollment: 1995–1998, follow up: 2014–2019). Specific genetic and environmental causes were identified in only a minority. Intellectual disability coexisted in 84%. Few became independent with 99% living at home with relatives, in disability group homes or in residential facilities. Seven individuals (3.7%) attained postsecondary education, two receiving baccalaureate degrees, two receiving associate degrees, and three receiving certificates from college disability programs. It may be anticipated that the long term outcome for individuals currently diagnosed with Autism Spectrum Disorder (ASD) will be substantially better than for individuals with Autistic Disorder in this cohort.

Conventional cytogenetic analysis of products of conception (POC) is of limited utility because of failed cultures, as well as microbial and maternal cell contamination (MCC). Optical genome mapping (OGM) is an emerging technology that has the potential to replace conventional cytogenetic methods. The use of OGM precludes the requirement for culturing (and related microbial contamination). However, a high percentage of MCC impedes a definitive diagnosis, which can be addressed by an additional pre-analytical quality control step that includes histological assessment of H&E stained slides from formalin-fixed paraffin embedded (FFPE) tissue with macro-dissection for chorionic villi to enrich fetal tissue component for single nucleotide polymorphism microarray (SNPM) analysis. To improve the diagnostic yield, an integrated workflow was devised that included MCC characterization of POC tissue, followed by OGM for MCC-negative cases or SNPM with histological assessment for MCC-positive cases. A result was obtained in 93% (29/31) of cases with a diagnostic yield of 45.1% (14/31) with the proposed workflow, compared to 9.6% (3/31) and 6.4% (2/31) with routine workflow, respectively. The integrated workflow with these technologies demonstrates the clinical utility and higher diagnostic yield in evaluating POC specimens.

Conventional cytogenetic analysis of products of conception (POC) is of limited utility because of failed cultures, microbial and maternal cell contamination (MCC). Optical genome mapping (OGM) is an emerging technology that has the potential to replace conventional cytogenetic methods. The use of OGM precludes the requirement for culturing (and related microbial contamination). However, a high percentage of MCC impedes a definitive diagnosis, which can be addressed by an additional pre-analytical quality control step that includes histological assessment of H&E stained slides from FFPE tissue with macro-dissection for Chorionic villi to enrich fetal tissue component for Single nucleotide polymorphism (SNP) microarray analysis. An internal audit of POC cases subjected to karyotype-only analysis showed a low yield on clinically actionable information that contributed to patient care. To improve the diagnostic yield, an integrated workflow was devised that included MCC characterization of POC tissue, followed by OGM for MCC negative cases or SNPM with histological assessment for MCC positive cases. A result was obtained in 93% (29/31) cases with a diagnostic yield of 45.1% (14/31) with proposed workflow compared to 9.6% (3/31) and 6.4% (2/31) with routine workflow, respectively. The integrated workflow with these technologies demonstrates the clinical utility and higher diagnostic yield in evaluating POC specimens.

Phelan-McDermid syndrome (PMS) (OMIM*606232) is a rare genetic disorder characterized by intellectual disability, autistic features, speech delay, minor dysmorphia, and seizures. This study was conducted to investigate the prevalence of seizures and the association with genetic and metabolic features since there has been little research related to seizures in PMS. For 57 individuals, seizure data was collected from caregiver interviews, genetic data from existing cytogenetic records and Sanger sequencing for nine 22q13 genes, and metabolic profiling from the Phenotype Mammalian MicroArray (PM-M) developed by Biolog. Results showed that 46% of individuals had seizures with the most common type being absence and grand-mal seizures. Seizures were most prevalent in individuals with pathogenic SHANK3 mutations (70%), those with deletion sizes >4 Mb (16%), and those with deletion sizes

The 22q11.2 deletion syndrome (22q11.2DS) is the most common genomic disorder in humans and is the result of a recurrent 1.5 to 2.5 Mb deletion, encompassing approximately 20–40 genes, respectively. The clinical presentation of the typical deletion includes: Velocardiofacial, Di George, Opitz G/BBB and Conotruncalanomaly face syndromes. Atypical deletions (proximal, distal or nested) are rare and characterized mainly by normal phenotype or mild intellectual disability and variable clinical features. The pathogenetic mechanisms underlying this disorder are not completely understood. Because the 22q11.2 region harbours genes coding for transcriptional factors and chromatin remodelers, in this study, we performed analysis of genome-wide DNA methylation of peripheral blood from 49 patients with 22q11.2DS using the Illumina Infinium Methylation EPIC bead chip arrays. This cohort comprises 43 typical, 2 proximal and 4 distal deletions. We demonstrated the evidence of a unique and highly specific episignature in all typical and proximal 22q11.2DS. The sensitivity and specificity of this signature was further confirmed by comparing it to over 1500 patients with other neurodevelopmental disorders with known episignatures. Mapping the 22q11.2DS DNA methylation episignature provides both novel insights into the molecular pathogenesis of this disorder and an effective tool in the molecular diagnosis of 22q11.2DS.

Background Copy-neutral absence of heterozygosity (CN-AOH) observed on a single chromosome or part of a chromosome may be indicative of uniparental disomy (UPD) and may require additional testing when such chromosomes or chromosome regions are known to harbor imprinted genes. Case presentation Here we report 2 cases of neonates that presented to clinic with hypotonia, poor oral skills including inability to feed by mouth, weak cry, no response to noxious stimulation and vertical plantar creases (case 1) and hypotonia and respiratory distress (case 2). A preliminary chromosome analysis showed normal karyotypes in both cases while the high-resolution single nucleotide polymorphism (SNP) microarray showed copy neutral absence of heterozygosity involving chromosome 15 distal long arm. In case 1, the CN-AOH involved a 28.7 Mb block from genomic coordinates 73703619_102429049. In case 2, the CN-AOH involved a 15.3 Mb block from genomic coordinates 54729197_70057534. In both cases, methylation-specific PCR did not detect an unmethylated allele for the SNRPN gene suggesting either a deletion of paternal allele or maternal UPD for chromosome 15. Since microarray analysis did not show any copy number alterations on chromosome 15, a microdeletion was ruled out. Conclusions Based on our cases, we suggest that CN-AOH on chromosome 15, even if it does not involve the critical region of 15q12q13, should warrant additional studies for diagnosis of Prader–Willi/Angelman syndromes.

Background Phelan-McDermid syndrome is characterized by a range of neurodevelopmental phenotypes with incomplete penetrance and variable expressivity. It is caused by a variable size and breakpoint microdeletions in the distal long arm of chromosome 22, referred to as 22q13.3 deletion syndrome, including the SHANK3 gene. Genetic defects in a growing number of neurodevelopmental genes have been shown to cause genome-wide disruptions in epigenomic profiles referred to as epi-signatures in affected individuals. Results In this study we assessed genome-wide DNA methylation profiles in a cohort of 22 individuals with Phelan-McDermid syndrome, including 11 individuals with large (2 to 5.8 Mb) 22q13.3 deletions, 10 with small deletions (SHANK3 and one mosaic case. We describe a novel genome-wide DNA methylation epi-signature in a subset of individuals with Phelan-McDermid syndrome. Conclusion We identified the critical region including the BRD1 gene as responsible for the Phelan-McDermid syndrome epi-signature. Metabolomic profiles of individuals with the DNA methylation epi-signature showed significantly different metabolomic profiles indicating evidence of two molecularly and phenotypically distinct clinical subtypes of Phelan-McDermid syndrome.

Autism spectrum disorder (ASD) is a constellation of neurodevelopmental disorders with high phenotypic and genetic heterogeneity, complicating the discovery of causative genes. Through a forward genetics approach selecting for defective vocalization in mice, we identified Kdm5a as a candidate ASD gene. To validate our discovery, we generated a Kdm5a knockout mouse model (Kdm5a-/-) and confirmed that inactivating Kdm5a disrupts vocalization. In addition, Kdm5a-/- mice displayed repetitive behaviors, sociability deficits, cognitive dysfunction, and abnormal dendritic morphogenesis. Loss of KDM5A also resulted in dysregulation of the hippocampal transcriptome. To determine if KDM5A mutations cause ASD in humans, we screened whole exome sequencing and microarray data from a clinical cohort. We identified pathogenic KDM5A variants in nine patients with ASD and lack of speech. Our findings illustrate the power and efficacy of forward genetics in identifying ASD genes and highlight the importance of KDM5A in normal brain development and function.

Purpose: We describe the clinical implementation of genome-wide DNA methylation analysis in rare disorders across the EpiSign diagnostic laboratory network and the assessment of results and clinical impact in the first subjects tested. Methods: We outline the logistics and data flow between an integrated network of clinical diagnostics laboratories in Europe, the United States, and Canada. We describe the clinical validation of EpiSign using 211 specimens and assess the test performance and diagnostic yield in the first 207 subjects tested involving two patient subgroups: the targeted cohort (subjects with previous ambiguous/inconclusive genetic findings including genetic variants of unknown clinical significance) and the screening cohort (subjects with clinical findings consistent with hereditary neurodevelopmental syndromes and no previous conclusive genetic findings). Results: Among the 207 subjects tested, 57 (27.6%) were positive for a diagnostic episignature including 48/136 (35.3%) in the targeted cohort and 8/71 (11.3%) in the screening cohort, with 4/207 (1.9%) remaining inconclusive after EpiSign analysis. Conclusion: This study describes the implementation of diagnostic clinical genomic DNA methylation testing in patients with rare disorders. It provides strong evidence of clinical utility of EpiSign analysis, including the ability to provide conclusive findings in the majority of subjects tested.

The course of 187 individuals ages 3-21 years with Autistic Disorder was traced through a period of 20 years (enrollment: 1995-1998, follow up: 2014-2019). Specific genetic and environmental causes were identified in only a minority. Intellectual disability coexisted in 84%. Few became independent with 99% living at home with relatives, in disability group homes or in residential facilities. Seven individuals (3.7%) attained postsecondary education, two receiving baccalaureate degrees, two receiving associate degrees, and three receiving certificates from college disability programs. It may be anticipated that the long term outcome for individuals currently diagnosed with Autism Spectrum Disorder (ASD) will be substantially better than for individuals with Autistic Disorder in this cohort.

Contains fulltext : 218274.pdf (Publisher’s version ) (Closed access) Genetic syndromes frequently present with overlapping clinical features and inconclusive or ambiguous genetic findings which can confound accurate diagnosis and clinical management. An expanding number of genetic syndromes have been shown to have unique genomic DNA methylation patterns (called "episignatures"). Peripheral blood episignatures can be used for diagnostic testing as well as for the interpretation of ambiguous genetic test results. We present here an approach to episignature mapping in 42 genetic syndromes, which has allowed the identification of 34 robust disease-specific episignatures. We examine emerging patterns of overlap, as well as similarities and hierarchical relationships across these episignatures, to highlight their key features as they are related to genetic heterogeneity, dosage effect, unaffected carrier status, and incomplete penetrance. We demonstrate the necessity of multiclass modeling for accurate genetic variant classification and show how disease classification using a single episignature at a time can sometimes lead to classification errors in closely related episignatures. We demonstrate the utility of this tool in resolving ambiguous clinical cases and identification of previously undiagnosed cases through mass screening of a large cohort of subjects with developmental delays and congenital anomalies. This study more than doubles the number of published syndromes with DNA methylation episignatures and, most significantly, opens new avenues for accurate diagnosis and clinical assessment in individuals affected by these disorders.

The original version of this article unfortunately contained a mistake. The following correction has therefore been made in the original: The spelling of Michael A. Levy’s name was incorrect. The corrected author list is given above. The original article has been corrected.

Key Clinical Message A focused genetic workup is useful in determining the cause of familial microcephaly, especially in the setting of mildly different phenotypes. As illustrated by this case from an impoverished international urban location, one must not assume the etiology for the apparent familial microcephaly is the same for all affected members.

Phelan-McDermid syndrome (PMS) is a rare neurodevelopmental disorder caused by rearrangements on chromosome 22q13.3 or sequence variants in SHANK3. Individuals with PMS caused by a 22q terminal deletion and a ring chromosome are at increased risk for Neurofibromatosis type 2 (NF2). However, the prevalence of NF2 in individuals with PMS and a r (22) is unknown. Individuals with PMS and a r (22) chromosome evaluated at the Greenwood Genetic Center (GGC) or by international collaborators, or identified through the PMS International Registry (PMSIR) were contacted and participated in a clinical questionnaire. Forty-four families completed the questionnaire and consented for the study. Of the individuals with a r (22), 7 (16%) carried a diagnosis of NF2. The average age of diagnosis of r (22) was 18 years old in individuals with NF2 and three years old in individuals without NF2 (p-value

A previous report described a unique phenotype associated with an apparently de novo 732 kb 19q13.32 microdeletion, consisting of intellectual disability, facial asymmetry, ptosis, oculomotor abnormalities, orofacial clefts, cardiac defects, scoliosis and chronic constipation. We report three unrelated patients with developmental delay and dysmorphic features, who were all found to have interstitial 19q13.32 microdeletions of varying sizes. Both the previously reported patient and our Patient 1 with a larger, 1.3-Mb deletion have distinctive dysmorphic features and medical problems, allowing us to define a recognizable 19q13.32 microdeletion syndrome. Patient 1 was hypotonic and dysmorphic at birth, with aplasia of the posterior corpus callosum, bilateral ptosis, oculomotor paralysis, down-slanting palpebral fissures, facial asymmetry, submucosal cleft palate, micrognathia, wide-spaced nipples, right-sided aortic arch, hypospadias, bilateral inguinal hernias, double toenail of the left second toe, partial 2–3 toe syndactyly, kyphoscoliosis and colonic atony. Therefore, the common features of the 19q13.32 microdeletion syndrome include facial asymmetry, ptosis, oculomotor paralysis, orofacial clefting, micrognathia, kyphoscoliosis, aortic defects and colonic atony. These findings are probably related to a deletion of some combination of the 20–23 genes in common between these two patients, especially NPAS1, NAPA, ARHGAP35 , SLC8A2 , DHX34 , MEIS3 , and ZNF541 . These candidate genes are expressed in the brain parenchyma, glia, heart, gastrointestinal tract and musculoskeletal system and likely play a fundamental role in the expression of this phenotype. This report delineates the phenotypic spectrum associated with the haploinsufficiency of genes found in 19q13.32.

Background Blepharophimosis-ptosis-epicanthus inversus syndrome is an autosomal dominant condition because of mutations or deletions of the FOXL2 gene. Microcephaly is not associated with FOXL2 mutations but has been reported in individuals with chromosome 3q deletions, which include the FOXL2 gene and other contiguous genes. The ATR gene has been reported as a candidate gene for microcephaly in individuals with contiguous deletion of chromosome 3q involving the FOXL2 gene. Patient We describe a girl with blepharophimosis-ptosis-epicanthus inversus syndrome along with acquired microcephaly and intellectual disability. Results Our patient had a deletion of chromosome 3q22.2q23, which does not include the ATR gene but does include the PIK3CB gene as a candidate gene for microcephaly. Conclusion We propose that the PIK3CB gene included in our patient's chromosome 3q deletion may be the gene responsible for microcephaly and other patients with blepharophimosis-ptosis-epicanthus inversus syndrome because of a chromosome 3q deletion.

Phelan–McDermid syndrome is a developmental disability syndrome with varying deletions of 22q13 and varying clinical severity. We tested the hypothesis that, in addition to loss of the telomeric gene SHANK3, specific genomic regions within 22q13 are associated with important clinical features. We used a customized oligo array comparative genomic hybridization of 22q12.3-terminus to obtain deletion breakpoints in a cohort of 70 patients with terminal 22q13 deletions. We used association and receiver operating characteristic statistical methods in a novel manner and also incorporated protein interaction networks to identify 22q13 genomic locations and genes associated with clinical features. Specific genomic regions and candidate genes within 22q13.2q13.32 were associated with severity of speech/language delay, neonatal hypotonia, delayed age at walking, hair-pulling behaviors, male genital anomalies, dysplastic toenails, large/fleshy hands, macrocephaly, short and tall stature, facial asymmetry, and atypical reflexes. We also found regions suggestive of a negative association with autism spectrum disorders. This work advances the field of research beyond the observation of a correlation between deletion size and phenotype and identifies candidate 22q13 loci, and in some cases specific genes, associated with singular clinical features observed in Phelan–McDermid syndrome. Our statistical approach may be useful in genotype–phenotype analyses for other microdeletion or microduplication syndromes. Genet Med 2014:16(4):318–328.

This study is the first to describe age-related changes in a large cohort of patients with Phelan-McDermid syndrome (PMS), also known as 22q13 deletion syndrome. Over a follow-up period of up to 12 years, physical examinations and structured interviews were conducted for 201 individuals diagnosed with PMS, 120 patients had a focused, high-resolution 22q12q13 array CGH, and 92 patients' deletions were assessed for parent-of-origin. 22q13 genomic anomalies include terminal deletions of 22q13 (89 %), terminal deletions and interstitial duplications (9 %), and interstitial deletions (2 %). Considering different age groups, in older patients, behavioral problems tended to subside, developmental abilities improved, and some features such as large or fleshy hands, full or puffy eyelids, hypotonia, lax ligaments, and hyperextensible joints were less frequent. However, the proportion reporting an autism spectrum disorder, seizures, and cellulitis, or presenting with lymphedema or abnormal reflexes increased with age. Some neurologic and dysmorphic features such as speech and developmental delay and macrocephaly correlated with deletion size. Deletion sizes in more recently diagnosed patients tend to be smaller than those diagnosed a decade earlier. Seventy-three percent of de novo deletions were of paternal origin. Seizures were reported three times more often among patients with a de novo deletion of the maternal rather than paternal chromosome 22. This analysis improves the understanding of the clinical presentation and natural history of PMS and can serve as a reference for the prevalence of clinical features in the syndrome.

Smith–Magenis syndrome (SMS) is a complex disorder whose clinical features include mild to severe intellectual disability with speech delay, growth failure, brachycephaly, flat midface, short broad hands, and behavioral problems. SMS is typically caused by a large deletion on 17p11.2 that encompasses multiple genes including the retinoic acid induced 1, RAI1, gene or a mutation in the RAI1 gene. Here we have evaluated 30 patients with suspected SMS and identified SMS-associated classical 17p11.2 deletions in six patients, an atypical deletion of ∼139 kb that partially deletes the RAI1 gene in one patient, and RAI1 gene nonsynonymous alterations of unknown significance in two unrelated patients. The RAI1 mutant proteins showed no significant alterations in molecular weight, subcellular localization and transcriptional activity. Clinical features of patients with or without 17p11.2 deletions and mutations involving the RAI1 gene were compared to identify phenotypes that may be useful in diagnosing patients with SMS.

Chromosomal imbalances are a major cause of intellectual disability (ID) and multiple congenital anomalies. We have clinically and molecularly characterized two patients with chromosome translocations and ID. Using whole genome array CGH analysis, we identified a microdeletion involving 4q21.3, unrelated to the translocations in both patients. We confirmed the 4q21.3 microdeletions using fluorescence in situ hybridization and quantitative genomic PCR. The corresponding deletion boundaries in the patients were further mapped and compared to previously reported 4q21 deletions and the associated clinical features. We determined a common region of deletion overlap that appears unique to ID, short stature, hypotonia, and dysmorphic facial features.

Split hand/foot malformation (SHFM) is characterized by underdeveloped or absent central digital rays, clefts of hands and feet, and variable syndactyly of the remaining digits. SHFM is a heterogeneous condition caused by abnormalities at one of multiple loci, including SHFM1 (SHFM1 at 7q21-q22), SHFM2 (Xq26), SHFM3 (FBXW4/DACTYLIN at 10q24), SHFM4 (TP63 at 3q27), and SHFM5 (DLX1 and DLX 2 at 2q31). SHFM3 is unique in that it is caused by submicroscopic tandem chromosome duplications of FBXW4/DACTYLIN. In order to show that array-based comparative genomic hybridization should be considered an essential aspect of the genetic analysis of patients with SHFM, we report on a family with two brothers who have ectrodactyly. Interestingly, both also have ocular abnormalities. Their sister and both parents are healthy. DNA of all five family members was analyzed using oligonucleotide-based DNA microarray and quantitative PCR. The two affected brothers were found to have a small duplication of approximately 539 kb at 10q24.32. The patients' sister and father do not have the microduplication, but qPCR showed that mother's DNA carries the duplication in 20% of blood lymphocytes. In this family, two children were affected with ectrodactyly having a duplication over the SHFM3 locus. The mother, who shows no clinical features of ectrodacytyly, is a mosaic for the same duplication. Therefore, we demonstrate that somatic/gonadal mosaicism is a mechanism that gives rise to SHFM. We also suggest that ocular abnormalities may be part of the clinical description of SHFM3.

X-Linked intellectual disability accounts for a significant fraction of males with cognitive impairment. Many of these males present with a non-syndromic phenotype and presently mutations in 17 X-linked genes are associated with these patients. Mutations in IL1RAPL1 have been found in multiple families with non-syndromic X-linked intellectual disability. All of the published mutations predict loss of function of the protein. We have identified an additional two families with deletions of a portion of the gene that give rise to cognitive impairment, as well as some behavioral problems and mild dysmorphism. Our clinical findings better delineate the phenotypic spectrum associated with IL1RAPL1 mutations.

We present two phenotypically similar females with Xp duplication who have autism and epilepsy. Case 1 is a 14-year-old Honduran female with autism and medically refractory complex partial, secondarily generalized epilepsy. Case 2 is a 3-year-old Austrian female with autism and medically refractory complex partial epilepsy. Both patients also share features of severe intellectual disability (case 1 has a developmental quotient of 23, case 2 has a developmental quotient of 42) and dysmorphic facial features. Autism was confirmed by thorough clinical evaluations and testing. Case 1 has a karyotype of 46,X,dup(X)(p11.2-p22.33) and a highly skewed X-inactivation pattern (94:6). Brain magnetic resonance imaging (MRI) and electroencephalogram (EEG) were abnormal. Case 2 has a 5-megabase duplication of Xp11.22-p11.23 on chromosome microarray analysis. The patient has a random X-inactivation pattern (77:23). Brain MRI was normal, but EEG was abnormal. Both patients have duplications involving the Xp11.22-p11.23 region, indicating that this is an area of interest for future translational autism research.

We have identified disruptions in the dedicator of cytokinesis 8 gene, DOCK8, in two unrelated patients with mental retardation (MR). In one patient, a male with MR and no speech, we mapped a genomic deletion of approximately 230 kb in subtelomeric 9p. In the second patient, a female with mental retardation and ectodermal dysplasia and a balanced translocation, t(X;9) (q13.1;p24), we mapped the 9p24 breakpoint to a region overlapping with the centromeric end of the 230-kb subtelomeric deletion. We characterized the DOCK8 gene from the critical 9p deletion region and determined that the longest isoform of the DOCK8 gene is truncated in both patients. Furthermore, the DOCK8 gene is expressed in several human tissues, including adult and fetal brain. Recently, a role for DOCK8 in processes that affect the organization of filamentous actin has been suggested. Several genes influencing the actin cytoskeleton have been implicated in human cognitive function and thus a possibility exists that the rare mutations in the DOCK8 gene may contribute to some cases of autosomal dominant mental retardation.

The authors report the rare association of Prader-Willi syndrome and short-chain acyl-CoA dehydrogenase gene variant. Prader-Willi syndrome, associated with paternal chromosome 15q11-q13 silencing, is characterized by neonatal/infantile hypotonia, growth failure, and neurodevelopmental delays in the first 1 to 2 years of life, typically followed by hyperphagia and obesity. Short-chain acyl-CoA dehydrogenase gene variant, with 625 G-to-A and 511 C-to-T changes, impairs C4-C6 fatty acid metabolism and variably causes neonatal/infantile hypotonia with developmental delays. The authors' patient continues to exhibit the classic severe growth failure of early infancy Prader-Willi syndrome at 40 months. Extensive laboratory investigations indicate that the short-chain acyl-CoA dehydrogenase gene variant is likely preventing or delaying the normal expression of the Prader-Willi syndrome phenotype.