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Contains fulltext : 167703.pdf (publisher's version ) (Closed access), Recently WAC was reported as a candidate gene for intellectual disability (ID) based on the identification of a de novo mutation in an individual with severe ID. WAC regulates transcription-coupled histone H2B ubiquitination and has previously been implicated in the 10p12p11 contiguous gene deletion syndrome. In this study, we report on 10 individuals with de novo WAC mutations which we identified through routine (diagnostic) exome sequencing and targeted resequencing of WAC in 2326 individuals with unexplained ID. All but one mutation was expected to lead to a loss-of-function of WAC. Clinical evaluation of all individuals revealed phenotypic overlap for mild ID, hypotonia, behavioral problems and distinctive facial dysmorphisms, including a square-shaped face, deep set eyes, long palpebral fissures, and a broad mouth and chin. These clinical features were also previously reported in individuals with 10p12p11 microdeletion syndrome. To investigate the role of WAC in ID, we studied the importance of the Drosophila WAC orthologue (CG8949) in habituation, a non-associative learning paradigm. Neuronal knockdown of Drosophila CG8949 resulted in impaired learning, suggesting that WAC is required in neurons for normal cognitive performance. In conclusion, we defined a clinically recognizable ID syndrome, caused by de novo loss-of-function mutations in WAC. Independent functional evidence in Drosophila further supported the role of WAC in ID. On the basis of our data WAC can be added to the list of ID genes with a role in transcription regulation through histone modification.

Contains fulltext : 167652.pdf (publisher's version ) (Closed access), Autosomal dominant polycystic liver disease (ADPLD) is caused by variants in PRKCSH, SEC63, and LRP5, whereas autosomal dominant polycystic kidney disease is caused by variants in PKD1 and PKD2. Liver cyst development in these disorders is explained by somatic loss-of-heterozygosity (LOH) of the wild-type allele in the developing cyst. We hypothesize that we can use this mechanism to identify novel disease genes that reside in LOH regions. In this study, we aim to map abnormal genomic regions using high-density SNP microarrays to find novel PLD genes. We collected 46 cysts from 23 patients with polycystic or sporadic hepatic cysts, and analyzed DNA from those cysts using high-resolution microarray (n=24) or Sanger sequencing (n=22). We here focused on regions of homozygosity on the autosomes (>3.0 Mb) and large CNVs (>1.0 Mb). We found frequent LOH in PRKCSH (22/29) and PKD1/PKD2 (2/3) cysts of patients with known heterozygous germline variants in the respective genes. In the total cohort, 12/23 patients harbored abnormalities outside of familiar areas. In individual ADPLD cases, we identified germline events: a 2q13 complex rearrangement resulting in BUB1 haploinsufficiency, a 47XXX karyotype, chromosome 9q copy-number loss, and LOH on chromosome 3p. The latter region was overlapping with an LOH region identified in two other cysts. Unique germline and somatic abnormalities occur frequently in and outside of known genes underlying cysts. Each liver cyst has a unique genetic makeup. LOH driver gene BUB1 may imply germline causes of genetic instability in PLD.

Item does not contain fulltext, We report four patients with a similar gain in 5p13.2 encompassing a single gene: SLC1A3. Behavioural problems resembling ADHD and/or autism-like features are observed which is in line with the glial glutamate transporter role of SLC1A3. We consider an association between SLC1A3 and the behavioural problems which can also be considered a contributing factor to behavioural problems in larger duplications overlapping the 5p13 microduplication syndrome region.

Contains fulltext : 165724.pdf (publisher's version ) (Closed access), PURPOSE: We aimed to identify a novel genetic cause of tooth agenesis (TA) and/or orofacial clefting (OFC) by combining whole-exome sequencing (WES) and targeted resequencing in a large cohort of TA and OFC patients. METHODS: WES was performed in two unrelated patients: one with severe TA and OFC and another with severe TA only. After deleterious mutations were identified in a gene encoding low-density lipoprotein receptor-related protein 6 (LRP6), all its exons were resequenced with molecular inversion probes in 67 patients with TA, 1,072 patients with OFC, and 706 controls. RESULTS: We identified a frameshift (c.4594delG, p.Cys1532fs) and a canonical splice-site mutation (c.3398-2A>C, p.?) in LRP6, respectively, in the patient with TA and OFC and in the patient with severe TA only. The targeted resequencing showed significant enrichment of unique LRP6 variants in TA patients but not in nonsyndromic OFC patients. Of the five variants in patients with TA, two affected the canonical splice site and three were missense variants; all variants segregated with the dominant phenotype, and in one case the missense mutation occurred de novo. CONCLUSION: Mutations in LRP6 cause TA in humans.Genet Med 18 11, 1158-1162.

Contains fulltext : 167384.pdf (Publisher’s version ) (Closed access), De novo disruptions of the neural transcription factor FOXP1 are a recently discovered, rare cause of sporadic intellectual disability (ID). We report three new cases of FOXP1-related disorder identified through clinical whole-exome sequencing. Detailed phenotypic assessment confirmed that global developmental delay, autistic features, speech/language deficits, hypotonia and mild dysmorphic features are core features of the disorder. We expand the phenotypic spectrum to include sensory integration disorder and hypertelorism. Notably, the etiological variants in these cases include two missense variants within the DNA-binding domain of FOXP1. Only one such variant has been reported previously. The third patient carries a stop-gain variant. We performed functional characterization of the three missense variants alongside our stop-gain and two previously described truncating/frameshift variants. All variants severely disrupted multiple aspects of protein function. Strikingly, the missense variants had similarly severe effects on protein function as the truncating/frameshift variants. Our findings indicate that a loss of transcriptional repression activity of FOXP1 underlies the neurodevelopmental phenotype in FOXP1-related disorder. Interestingly, the three novel variants retained the ability to interact with wild-type FOXP1, suggesting these variants could exert a dominant-negative effect by interfering with the normal FOXP1 protein. These variants also retained the ability to interact with FOXP2, a paralogous transcription factor disrupted in rare cases of speech and language disorder. Thus, speech/language deficits in these individuals might be worsened through deleterious effects on FOXP2 function. Our findings highlight that de novo FOXP1 variants are a cause of sporadic ID and emphasize the importance of this transcription factor in neurodevelopment.

Contains fulltext : 152531.pdf (publisher's version ) (Open Access), Over 95% of all synovial sarcomas (SS) share a unique translocation, t(X;18), however, they show heterogeneous clinical behavior. We analyzed multiple SS to reveal additional genetic alterations besides the translocation. Twenty-six SS from 22 patients were sequenced for 409 cancer-related genes using the Comprehensive Cancer Panel (Life Technologies, USA) on an Ion Torrent platform. The detected variants were verified by Sanger sequencing and compared to matched normal DNAs. Copy number variation was assessed in six tumors using the Oncoscan array (Affymetrix, USA). In total, eight somatic mutations were detected in eight samples. These mutations have not been reported previously in SS. Two of these, in KRAS and CCND1, represent known oncogenic mutations in other malignancies. Additional mutations were detected in RNF213, SEPT9, KDR, CSMD3, MLH1 and ERBB4. DNA alterations occurred more often in adult tumors. A distinctive loss of 6q was found in a metastatic lesion progressing under pazopanib, but not in the responding lesion. Our results emphasize t(X;18) as a single initiating event in SS and as the main oncogenic driver. Our results also show the occurrence of additional genetic events, mutations or chromosomal aberrations, occurring more frequently in SS with an onset in adults.

Contains fulltext : 154153.pdf (publisher's version ) (Open Access), Clusters of functionally related genes can be disrupted by a single copy number variant (CNV). We demonstrate that the simultaneous disruption of multiple functionally related genes is a frequent and significant characteristic of de novo CNVs in patients with developmental disorders (P = 1 x 10(-3)). Using three different functional networks, we identified unexpectedly large numbers of functionally related genes within de novo CNVs from two large independent cohorts of individuals with developmental disorders. The presence of multiple functionally related genes was a significant predictor of a CNV's pathogenicity when compared to CNVs from apparently healthy individuals and a better predictor than the presence of known disease or haploinsufficient genes for larger CNVs. The functionally related genes found in the de novo CNVs belonged to 70% of all clusters of functionally related genes found across the genome. De novo CNVs were more likely to affect functional clusters and affect them to a greater extent than benign CNVs (P = 6 x 10(-4)). Furthermore, such clusters of functionally related genes are phenotypically informative: Different patients possessing CNVs that affect the same cluster of functionally related genes exhibit more similar phenotypes than expected (P < 0.05). The spanning of multiple functionally similar genes by single CNVs contributes substantially to how these variants exert their pathogenic effects.

Contains fulltext : 153459.pdf (publisher's version ) (Closed access), Limited data is available on the genetic features of primary leptomeningeal melanocytic neoplasms (LMNs). Similarities with uveal melanoma were recently suggested as both entities harbor oncogenic mutations in GNAQ and GNA11. Whether primary LMNs share additional genetic alterations with uveal melanoma including copy number variations is unknown. Twenty primary LMNs ranging from benign and intermediate-grade melanocytomas to melanomas were tested by direct sequencing for hotspot mutations in the genes GNA11, GNAQ, BRAF, NRAS and HRAS. Furthermore, the lesions were tested for copy number variations of chromosomes frequently present in uveal melanoma (1p, 3, 6 and 8q) by multiplex ligation-dependent probe amplification (MLPA). Genome-wide analyses of copy number alterations of two leptomeningeal melanocytic neoplasms were performed using the OncoScan SNP-array. GNAQ(Q209) mutations were present in eleven LMNs, while two of 20 cases carried a GNA11(Q209) mutation. No BRAF, HRAS or NRAS hotspot mutations were detected. Monosomy 3 and gain of 8q were present in one leptomeningeal melanoma, and one intermediate-grade melanocytoma harbored a gain of chromosome 6. With MLPA, the melanocytomas did not show any further gross chromosomal variations. Our data shows that primary LMNs, like uveal melanoma, harbor oncogenic mutations in GNAQ and GNA11 but lack mutations in BRAF, NRAS and HRAS. This finding may help in the differential diagnosis between a primary LMN and a metastasis from a cutaneous melanoma to the central nervous system. Copy number variations in some aggressive LMNs resemble those present in uveal melanoma but their prognostic significance is unclear.

Item does not contain fulltext, This report is regarding a Dutch female with microcephaly, mild intellectual disability (ID), gonadal dysgenesis and dysmorphic facial features with synophrys. Upon genotyping, an ~455 kb de novo deletion encompassing the first exon of NRXN1 was found. Bidirectional sequencing of the coding exons of the NRXN1 alpha isoform was subsequently performed to investigate the possibility of a pathogenic mutation on the other allele, but we could not find any other mutation. Previously, many heterozygous mutations as well as microdeletions in NRXN1 were shown to be associated with ID, autism, schizophrenia, and other psychiatric and psychotic disorders. Our results are in agreement with other reports that show that NRXN1 deletions can lead to ID, microcephaly and mild dysmorphic features. However, this is the first report of gonadal dysgenesis being associated with such deletions. It is not clear whether there is a causal relationship between the NRXN1 deletion and gonadal dysgenesis, but it is of interest that the FSHR gene, which encodes the follicle-stimulating hormone receptor causative correlation that is mutated in ovarian dysgenesis, is located proximal to the NRXN1 gene. Given that most of the females carrying NRXN1 deletions have been diagnosed at a prepubertal age, gynecologic screening of female carriers of a NRXN1 deletion is warranted.

Contains fulltext : 153652.pdf (publisher's version ) (Open Access), BACKGROUND: Heterozygous loss-of-function mutations in the X-linked CASK gene cause progressive microcephaly with pontine and cerebellar hypoplasia (MICPCH) and severe intellectual disability (ID) in females. Different CASK mutations have also been reported in males. The associated phenotypes range from nonsyndromic ID to Ohtahara syndrome with cerebellar hypoplasia. However, the phenotypic spectrum in males has not been systematically evaluated to date. METHODS: We identified a CASK alteration in 8 novel unrelated male patients by targeted Sanger sequencing, copy number analysis (MLPA and/or FISH) and array CGH. CASK transcripts were investigated by RT-PCR followed by sequencing. Immunoblotting was used to detect CASK protein in patient-derived cells. The clinical phenotype and natural history of the 8 patients and 28 CASK-mutation positive males reported previously were reviewed and correlated with available molecular data. RESULTS: CASK alterations include one nonsense mutation, one 5-bp deletion, one mutation of the start codon, and five partial gene deletions and duplications; seven were de novo, including three somatic mosaicisms, and one was familial. In three subjects, specific mRNA junction fragments indicated in tandem duplication of CASK exons disrupting the integrity of the gene. The 5-bp deletion resulted in multiple aberrant CASK mRNAs. In fibroblasts from patients with a CASK loss-of-function mutation, no CASK protein could be detected. Individuals who are mosaic for a severe CASK mutation or carry a hypomorphic mutation still showed detectable amount of protein. CONCLUSIONS: Based on eight novel patients and all CASK-mutation positive males reported previously three phenotypic groups can be distinguished that represent a clinical continuum: (i) MICPCH with severe epileptic encephalopathy caused by hemizygous loss-of-function mutations, (ii) MICPCH associated with inactivating alterations in the mosaic state or a partly penetrant mutation, and (iii) s

Contains fulltext : 155339.PDF (publisher's version ) (Open Access), Readily-accessible and standardised capture of genotypic variation has revolutionised our understanding of the genetic contribution to disease. Unfortunately, the corresponding systematic capture of patient phenotypic variation needed to fully interpret the impact of genetic variation has lagged far behind. Exploiting deep and systematic phenotyping of a cohort of 197 patients presenting with heterogeneous developmental disorders and whose genomes harbour de novo CNVs, we systematically applied a range of commonly-used functional genomics approaches to identify the underlying molecular perturbations and their phenotypic impact. Grouping patients into 408 non-exclusive patient-phenotype groups, we identified a functional association amongst the genes disrupted in 209 (51%) groups. We find evidence for a significant number of molecular interactions amongst the association-contributing genes, including a single highly-interconnected network disrupted in 20% of patients with intellectual disability, and show using microcephaly how these molecular networks can be used as baits to identify additional members whose genes are variant in other patients with the same phenotype. Exploiting the systematic phenotyping of this cohort, we observe phenotypic concordance amongst patients whose variant genes contribute to the same functional association but note that (i) this relationship shows significant variation across the different approaches used to infer a commonly perturbed molecular pathway, and (ii) that the phenotypic similarities detected amongst patients who share the same inferred pathway perturbation result from these patients sharing many distinct phenotypes, rather than sharing a more specific phenotype, inferring that these pathways are best characterized by their pleiotropic effects.

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Contains fulltext : 155230.pdf (publisher's version ) (Closed access), Many laboratories now use genomic microarrays as their first-tier diagnostic test for copy number variation (CNV) detection. In addition, whole exome sequencing is increasingly being offered as a diagnostic test for heterogeneous disorders. Although mostly used for the detection of point mutations and small insertion-deletions, exome sequencing can also be used to call CNVs, allowing combined small and large variant analysis. Whole genome sequencing in addition to these advantages also offers the potential to characterize CNVs to unprecedented levels of accuracy, providing position and orientation information. In this review, we discuss the clinical potential of CNV identification in whole exome sequencing and whole genome sequencing data and the implications this has on diagnostic laboratories.

Item does not contain fulltext, To further elucidate the genetic underpinnings of uveal melanoma (UM) and identify new markers that correlate with disease outcome, archival formalin-fixed, paraffin-embedded enucleation specimens from 25 patients with UM and a mean follow-up of 14 years were analyzed for whole-genome copy-number alterations using OncoScan analysis. Copy-number alterations of chromosomes 1, 3, 6, and 8 were also analyzed in these tumors using multiplex ligation-dependent probe-amplification, and mutations in GNAQ, GNA11, and BAP1 were searched for by Sanger sequencing. Our study confirms the previously reported GNAQ and GNA11 mutation frequencies in UMs as well as the presence of monosomy 3 as a factor strongly indicating poor prognosis. Two cases with metastatic disease, but without monosomy of chromosome 3, showed loss of a small region in the distal part of chromosome 2p. Also, UMs leading to metastatic disease had more chromosomal aberrations than those without metastases. Three UMs lacking a GNAQ or a GNA11 mutation showed a gain of chromosome 8q; one of these cases showed extensive chromothripsis. Another case (with suspect lung metastasis) showed focal chromothripsis. Our whole-genome copy-number analysis shows that focal loss of chromosome 2p may be involved in the metastatic spread of UMs without monosomy 3; metastatic UMs carry more chromosomal aberrations than those without metastases; and chromothripsis may play a role in the oncogenesis of UMs, but does not necessarily indicate a poor prognosis. The clinical and particularly diagnostic utility of these findings needs to be corroborated in a larger set of patients with UM.

Contains fulltext : 152955.pdf (publisher's version ) (Closed access), KCNH1 mutations have recently been described in six individuals with Temple-Baraitser syndrome (TMBTS) and six individuals with Zimmermann-Laband syndrome (ZLS). TMBTS is characterized by intellectual disability (ID), epilepsy, dysmorphic facial features, broad thumbs and great toes with absent/hypoplastic nails. ZLS is characterized by facial dysmorphism including coarsening of the face and a large nose, gingival enlargement, ID, hypoplasia of terminal phalanges and nails and hypertrichosis. In this study, we present four additional unrelated individuals with de novo KCNH1 mutations from ID cohorts. We report on a novel recurrent pathogenic KCNH1 variant in three individuals and add a fourth individual with a previously TMBTS-associated KCNH1 variant. Neither TMBTS nor ZLS was suspected clinically. KCNH1 encodes a voltage-gated potassium channel, which is not only highly expressed in the central nervous system, but also seems to play an important role during development. Clinical evaluation of our mutation-positive individuals revealed that one of the main characteristics of TMBTS/ZLS, namely the pronounced nail hypoplasia of the great toes and thumbs, can be mild and develop over time. Clinical comparison of all published KCNH1 mutation-positive individuals revealed a similar facial but variable limb phenotype. KCNH1 mutation-positive individuals present with severe ID, neonatal hypotonia, hypertelorism, broad nasal tip, wide mouth, nail a/hypoplasia, a proximal implanted and long thumb and long great toes. In summary, we show that the phenotypic variability of individuals with KCNH1 mutations is more pronounced than previously expected, and we discuss whether KCNH1 mutations allow for "lumping" or for "splitting" of TMBTS and ZLS.

Contains fulltext : 138882.pdf (publisher's version ) (Open Access), Intellectual disability (ID) is a major health problem mostly with an unknown etiology. Recently exome sequencing of individuals with ID identified novel genes implicated in the disease. Therefore the purpose of the present study was to identify the genetic cause of ID in one syndromic and two non-syndromic Pakistani families. Whole exome of three ID probands was sequenced. Missense variations in two plausible novel genes implicated in autosomal recessive ID were identified: lysine (K)-specific methyltransferase 2B (KMT2B), zinc finger protein 589 (ZNF589), as well as hedgehog acyltransferase (HHAT) with a de novo mutation with autosomal dominant mode of inheritance. The KMT2B recessive variant is the first report of recessive Kleefstra syndrome-like phenotype. Identification of plausible causative mutations for two recessive and a dominant type of ID, in genes not previously implicated in disease, underscores the large genetic heterogeneity of ID. These results also support the viewpoint that large number of ID genes converge on limited number of common networks i.e. ZNF589 belongs to KRAB-domain zinc-finger proteins previously implicated in ID, HHAT is predicted to affect sonic hedgehog, which is involved in several disorders with ID, KMT2B associated with syndromic ID fits the epigenetic module underlying the Kleefstra syndromic spectrum. The association of these novel genes in three different Pakistani ID families highlights the importance of screening these genes in more families with similar phenotypes from different populations to confirm the involvement of these genes in pathogenesis of ID.

Item does not contain fulltext, Optic nerve atrophy and hypoplasia can be primary disorders or can result from trans-synaptic degeneration arising from cerebral visual impairment (CVI). Here we report six individuals with CVI and/or optic nerve abnormalities, born after an uneventful pregnancy and delivery, who have either de novo heterozygous missense mutations in NR2F1, also known as COUP-TFI, or deletions encompassing NR2F1. All affected individuals show mild to moderate intellectual impairment. NR2F1 encodes a nuclear receptor protein that regulates transcription. A reporter assay showed that missense mutations in the zinc-finger DNA-binding domain and the putative ligand-binding domain decrease NR2F1 transcriptional activity. These findings indicate that NR2F1 plays an important role in the neurodevelopment of the visual system and that its disruption can lead to optic atrophy with intellectual disability.

Item does not contain fulltext, BACKGROUND: Cerebral visual impairment (CVI) is a disorder in projection and/or interpretation of the visual input in the brain and accounts for 27% of the visually impaired children. AIM: A large cohort of patients with CVI was investigated in order to ascertain the relevance of chromosomal aberrations in the etiology of this disorder. METHODS: 607 patients with CVI and a visual acuity

Contains fulltext : 136372.pdf (Publisher’s version ) (Closed access), Neu-Laxova syndrome (NLS) is a rare autosomal-recessive disorder characterized by a recognizable pattern of severe malformations leading to prenatal or early postnatal lethality. Homozygous mutations in PHGDH, a gene involved in the first and limiting step in L-serine biosynthesis, were recently identified as the cause of the disease in three families. By studying a cohort of 12 unrelated families affected by NLS, we provide evidence that NLS is genetically heterogeneous and can be caused by mutations in all three genes encoding enzymes of the L-serine biosynthesis pathway. Consistent with recently reported findings, we could identify PHGDH missense mutations in three unrelated families of our cohort. Furthermore, we mapped an overlapping homozygous chromosome 9 region containing PSAT1 in four consanguineous families. This gene encodes phosphoserine aminotransferase, the enzyme for the second step in L-serine biosynthesis. We identified six families with three different missense and frameshift PSAT1 mutations fully segregating with the disease. In another family, we discovered a homozygous frameshift mutation in PSPH, the gene encoding phosphoserine phosphatase, which catalyzes the last step of L-serine biosynthesis. Interestingly, all three identified genes have been previously implicated in serine-deficiency disorders, characterized by variable neurological manifestations. Our findings expand our understanding of NLS as a disorder of the L-serine biosynthesis pathway and suggest that NLS represents the severe end of serine-deficiency disorders, demonstrating that certain complex syndromes characterized by early lethality could indeed be the extreme end of the phenotypic spectrum of already known disorders.

Contains fulltext : 137136.pdf (publisher's version ) (Open Access)

Item does not contain fulltext, MEIS2 is a homeodomain-containing transcription factor of the TALE superfamily that has been proven important for development. We confirm and extend a recent single clinical report stating that deletions in MEIS2 can cause cleft palate [Crowley et al. (2010); Am J Med Genet 152A:1326-1327]. Here we report on five additional patients with 15q14 deletions of sizes 0.6, 0.6, 1.0, 1.9, and 4.8 Mb, respectively, all involving MEIS2. In addition, we present a family with four affected individuals and an intragenic 58 kb direct duplication disrupting MEIS2. In total, 7/9 cases had clefting, from mild (submucous cleft palate) to severe (cleft lip and palate), and 3/9 cases had ventricular septal defects. All cases had delayed motor development and most had learning disability, at worst in the mild intellectual disability range. The cases had overlapping facial features (broad forehead, finely arched eyebrows, mildly shortened philtrum, and tented upper lip) but individually they were not considered to be dysmorphic. Our results show that MEIS2 is a gene needed for palate closure. In syndromic cases of cleft palate, MEIS2 should be considered among the candidate genes, for example, in cases without 22q11.2 deletions. (c) 2014 Wiley Periodicals, Inc.

Item does not contain fulltext, OBJECTIVE: To establish whether uniparental disomy (UPD) could represent an outcome of embryonic aneuploidy self-correction and its relevance to preimplantation genetic diagnosis, and to validate a method of UPD detection in limited quantities of cells and determine the frequency of UPD in a large sample size of human blastocysts. DESIGN: Retrospective observational. SETTING: Academic center for reproductive medicine. PATIENT(S): Couples undergoing in vitro fertilization (IVF) treatment whose embryos underwent trophectoderm biopsy single-nucleotide polymorphism (SNP) array-based 24-chromosome aneuploidy screening. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Rate of UPD observed in the human blastocyst. RESULT(S): After application of defined thresholds, 2 of 3,401 blastocysts were found to possess isodisomy, and 0 were found to possess heterodisomy. The overall frequency of UPD in the human blastocyst was therefore 0.06%. CONCLUSION(S): This validated method of detection indicates that UPD is extremely rare and suggests that routine screening during preimplantation genetic diagnosis (PGD) may not be necessary. Furthermore, chromosomal UPD is unlikely to explain or support the existence of embryonic self-correction.

Item does not contain fulltext, OBJECTIVE: Seizure disorder is one of the most relevant clinical manifestations in Wolf-Hirschhorn syndrome (WHS) and it acts as independent prognostic factor for the severity of intellectual disability (ID). LETM1, encoding a mitochondrial protein playing a role in K(+) /H(+) exchange and in Ca(2+) homeostasis, is currently considered the major candidate gene. However, whether haploinsufficiency limited to LETM1 is enough to cause epilepsy is still unclear. The main purpose of the present research is to define the 4p chromosome regions where genes for seizures reside. METHODS: Comparison of our three unusual 4p16.3 deletions with 13 literature reports. Array-comparative genomic hybridization (a-CGH). Real-time polymerase chain reaction (RT-PCR) on messanger RNA (mRNA) of LETM1 and CPLX1. Direct sequencing of LETM1. RESULTS: Three unusual 4p16.3 deletions were detected by array-CGH in absence of a obvious clinical diagnosis of WHS. Two of these, encompassing LETM1, were found in subjects who never had seizures. The deletions were interstitial, spanning 1.1 Mb with preservation of the terminal 1.77 Mb region in one case and 0.84 Mb with preservation of the terminal 1.07 Mb region in the other. The other deletion was terminal, affecting a 0.564 Mb segment, with preservation of LETM1, and it was associated with seizures and learning difficulties. Upon evaluating our patients along with literature reports, we noted that six of eight subjects with terminal 4p deletions preserving LETM1 had seizures, whereas seven of seven with interstitial deletions including LETM1 and preserving the terminal 1 Mb region on 4p did not. An additional chromosome region for seizures is suggested, falling within the terminal 1.5 Mb on 4p, not including LETM1. SIGNIFICANCE: We consider that haploinsufficiency not limited to LETM1 but including other genes acts as a risk factor for the WHS-associated seizure disorder, according to a comorbidity model of pathogenesis. Additional candidate genes

Contains fulltext : 138213.pdf (publisher's version ) (Open Access), BACKGROUND: Characteristic genomic abnormalities in patients with B cell chronic lymphocytic leukemia (CLL) have been shown to provide important prognostic information. Fluorescence in situ hybridization (FISH) and multiplex ligation-dependent probe amplification (MLPA), currently used in clinical diagnostics of CLL, are targeted tests aimed at specific genomic loci. Microarray-based genomic profiling is a new high-resolution tool that enables genome-wide analyses. The aim of this study was to compare two recently launched genomic microarray platforms, i.e., the CytoScan HD Array (Affymetrix) and the HumanOmniExpress Array (Illumina), with FISH and MLPA to ascertain whether these latter tests can be replaced by either one of the microarray platforms in a clinical diagnostic setting. RESULT: Microarray-based genomic profiling and FISH were performed in all 28 CLL patients. For an unbiased comparison of the performance of both microarray platforms 9 patients were evaluated on both platforms, resulting in the identification of exactly identical genomic aberrations. To evaluate the detection limit of the microarray platforms we included 7 patients in which the genomic abnormalities were present in a relatively low percentage of the cells (range 5-28%) as previously determined by FISH. We found that both microarray platforms allowed the detection of copy number abnormalities present in as few as 16% of the cells. In addition, we found that microarray-based genomic profiling allowed the identification of genomic abnormalities that could not be detected by FISH and/or MLPA, including a focal TP53 loss and copy neutral losses of heterozygosity of chromosome 17p. CONCLUSION: From our results we conclude that although the microarray platforms exhibit a somewhat lower limit of detection compared to FISH, they still allow the detection of copy number abnormalities present in as few as 16% of the cells. By applying similar interpretation criteria, the results obtained from both

Item does not contain fulltext, New human mutations are thought to originate in germ cells, thus making a recurrence of the same mutation in a sibling exceedingly rare. However, increasing sensitivity of genomic technologies has anecdotally revealed mosaicism for mutations in somatic tissues of apparently healthy parents. Such somatically mosaic parents might also have germline mosaicism that can potentially cause unexpected intergenerational recurrences. Here, we show that somatic mosaicism for transmitted mutations among parents of children with simplex genetic disease is more common than currently appreciated. Using the sensitivity of individual-specific breakpoint PCR, we prospectively screened 100 families with children affected by genomic disorders due to rare deletion copy-number variants (CNVs) determined to be de novo by clinical analysis of parental DNA. Surprisingly, we identified four cases of low-level somatic mosaicism for the transmitted CNV in DNA isolated from parental blood. Integrated probabilistic modeling of gametogenesis developed in response to our observations predicts that mutations in parental blood increase recurrence risk substantially more than parental mutations confined to the germline. Moreover, despite the fact that maternally transmitted mutations are the minority of alleles, our model suggests that sexual dimorphisms in gametogenesis result in a greater proportion of somatically mosaic transmitting mothers who are thus at increased risk of recurrence. Therefore, somatic mosaicism together with sexual differences in gametogenesis might explain a considerable fraction of unexpected recurrences of X-linked recessive disease. Overall, our results underscore an important role for somatic mosaicism and mitotic replicative mutational mechanisms in transmission genetics.

Item does not contain fulltext, Microdeletions of the 5q11.2 region are rare; in literature only two patients with a deletion in this region have been reported so far. In this study, we describe four additional patients and further define this new 5q11.2 microdeletion syndrome. A comparison of the features observed in all six patients with overlapping 5q11.2 deletions showed a phenotypic spectrum that overlaps with CHARGE syndrome and 22q11.2 deletion syndrome including choanal atresia, developmental delay, heart defects, external ear abnormalities, and short stature. No colobomas or abnormalities of semicircular canals and olfactory nerves were reported. Two male patients had genital abnormalities. We estimated a 2.0 Mb (53.0-55.0 Mb) Shortest Region of Overlap (SRO) for the main clinical characteristics of the syndrome. This region contains nine genes and two non-coding microRNAs. In this region DHX29 serves as the candidate gene as it encodes an ATP-dependent RNA-helicase that is involved in the initiation of RNA translation. Screening a small cohort of 14 patients who presented the main features, however, did not reveal any pathogenic abnormalities of DHX29.

Item does not contain fulltext, BACKGROUND: Intellectual disability (ID) is a common neurodevelopmental disorder affecting 1-3% of the general population. Mutations in more than 10% of all human genes are considered to be involved in this disorder, although the majority of these genes are still unknown. OBJECTIVES: We investigated 19 small non-consanguineous families with two to five affected siblings in order to identify pathogenic gene variants in known, novel and potential ID candidate genes. Non-consanguineous families have been largely ignored in gene identification studies as small family size precludes prior mapping of the genetic defect. METHODS AND RESULTS: Using exome sequencing, we identified pathogenic mutations in three genes, DDHD2, SLC6A8, and SLC9A6, of which the latter two have previously been implicated in X-linked ID phenotypes. In addition, we identified potentially pathogenic mutations in BCORL1 on the X-chromosome and in MCM3AP, PTPRT, SYNE1, and ZNF528 on autosomes. CONCLUSIONS: We show that potentially pathogenic gene variants can be identified in small, non-consanguineous families with as few as two affected siblings, thus emphasising their value in the identification of syndromic and non-syndromic ID genes.

Item does not contain fulltext, The clinical and molecular characterizations of two patients with a 1.4 Mb overlapping deletion in the 6p25.1p24.3 region are reported. In addition to the mild intellectual disability, they shared feeding problems in infancy and several dysmorphic facial features including a prominent forehead, almond-shaped eyes, a short philtrum, and low-set ears with square helices. The overlapping deleted region harbors six genes (RREB1, NRN1, CAGE1, LY86, SSR1, and F13A1), of which NRN1 and RREB1 are considered as candidate genes for the intellectual disability and the overlapping dysmorphism, respectively.

Item does not contain fulltext, Anorectal malformations (ARMs) comprise a broad spectrum of conditions ranging from mild anal anomalies to complex cloacal malformations. In 40-50% of cases, ARM occurs within the context of defined genetic syndromes or complex multiple congenital anomalies, such as VATER/VACTERL (vertebral defects [V], ARMs [A], cardiac defects [C], tracheoesophageal fistula with or without esophageal atresia [TE], renal malformations [R], and limb defects [L]) association. Here, we report the identification of deletions at chromosome 13q using single nucleotide polymorphism-based array analysis in two patients with mild ARM as part of VATER/VACTERL and VATER/VACTERL-like associations. Both deletions overlap the previously defined critical region for ARM. Heterozygous Efnb2 murine knockout models presenting with mild ARM suggest EFNB2 as an excellent candidate gene in this region. Our patients showed a mild ARM phenotype, closely resembling that of the mouse. We performed a comprehensive mutation analysis of the EFNB2 gene in 331 patients with isolated ARM, or ARM as part of VATER/VACTERL or VATER/VACTERL-like associations. However, we did not identify any disease-causing mutations. Given the convincing argument for EFNB2 as a candidate gene for ARM, analyses of larger samples and screening of functionally relevant non-coding regions of EFNB2 are warranted. In conclusion, our report underlines the association of chromosome 13q deletions with ARM, suggesting that routine molecular diagnostic workup should include the search for these deletions. Despite the negative results of our mutation screening, we still consider EFNB2 an excellent candidate gene for contributing to the development of ARM in humans. (c) 2013 Wiley Periodicals, Inc.

Item does not contain fulltext, Trisomies of 12q23q24 have been described rarely in literature. Only a few case-reports have been published so far almost exclusively reporting on neonates or young infants. We present a 16-year-old patient with a trisomy of 12q23.3q24.3. Full phenotypic evaluation at this age comprised: severe growth retardation, developmental delay, intellectual disability and characteristic facial dysmorphisms. Initially, in the proband an insertion was cytogenetically mapped at chromosome 16: der(16)dir ins(16; 12)(q12.1; q24.11q24.31). The mother appeared carrier of a balanced insertion. Subsequent SNP-array analysis in the proband revealed a 16.3 Mb gain of 12q23.3 --> 12q24.31. The clinical and molecular findings in this patient are compared with previous literature on cases with overlapping isolated 12q trisomies. The common phenotype observed consists of severe growth retardation, intellectual disability and characteristic facial features with hypertelorism, flat nasal bridge, down-turned mouth and poorly lobulated/low set ears. In addition, pediatric follow up into adolescence showed feeding difficulties requiring gastric tube feeding, recurrent otitis media, progressive contractures of joints and genito-renal problems, speech, communication and behavioral problems. These symptoms should be taken into account in the care and management of children with this condition.

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Contains fulltext : 97138.pdf (publisher's version ) (Closed access), The oxidative phosphorylation (OXPHOS) system is under control of both the mitochondrial and the nuclear genomes; 13 subunits are synthesized by the mitochondrial translation machinery. We report a patient with Cornelia de Lange-like dysmorphic features, brain abnormalities and hypertrophic cardiomyopathy, and studied the genetic defect responsible for the combined OXPHOS complex I, III and IV deficiency observed in fibroblasts. The combination of deficiencies suggested a primary defect associated with the synthesis of mitochondrially encoded OXPHOS subunits. Analysis of mitochondrial protein synthesis revealed a marked impairment in mitochondrial translation. Homozygosity mapping and sequence analysis of candidate genes revealed a homozygous mutation in MRPS22, a gene encoding a mitochondrial ribosomal small subunit protein. The mutation predicts a Leu215Pro substitution at an evolutionary conserved site. Mutations in genes implicated in Cornelia de Lange syndrome or copy number variations were not found. Transfection of patient fibroblasts, in which MRPS22 was undetectable, with the wild-type MRPS22 cDNA restored the amount and activity of OXPHOS complex IV, as well as the 12S rRNA transcript level to normal values. These findings demonstrate the pathogenicity of the MRPS22 mutation and stress the significance of mutations in nuclear genes, including genes that have no counterparts in lower species like bacteria and yeast, for mitochondrial translation defects.

Contains fulltext : 87261.pdf (publisher's version ) (Closed access)

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Contains fulltext : 81716.pdf (publisher's version ) (Closed access)

Contains fulltext : 80656.pdf (publisher's version ) (Closed access), BACKGROUND: The 9q subtelomeric deletion syndrome (9qSTDS) is clinically characterised by moderate to severe mental retardation, childhood hypotonia and facial dysmorphisms. In addition, congenital heart defects, urogenital defects, epilepsy and behavioural problems are frequently observed. The syndrome can be either caused by a submicroscopic 9q34.3 deletion or by intragenic EHMT1 mutations leading to haploinsufficiency of the EHMT1 gene. So far it has not been established if and to what extent other genes in the 9q34.3 region contribute to the phenotype observed in deletion cases. This study reports the largest cohort of 9qSTDS cases so far. METHODS AND RESULTS: By a multiplex ligation dependent probe amplification (MLPA) approach, the authors identified and characterised 16 novel submicroscopic 9q deletions. Direct sequence analysis of the EHMT1 gene in 24 patients exhibiting the 9qSTD phenotype without such deletion identified six patients with an intragenic EHMT1 mutation. Five of these mutations predict a premature termination codon whereas one mutation gives rise to an amino acid substitution in a conserved domain of the protein. CONCLUSIONS: The data do not provide any evidence for phenotype-genotype correlations between size of the deletions or type of mutations and severity of clinical features. Therefore, the authors confirm the EHMT1 gene to be the major determinant of the 9qSTDS phenotype. Interestingly, five of six patients who had reached adulthood had developed severe psychiatric pathology, which may indicate that EHMT1 haploinsufficiency is associated with neurodegeneration in addition to neurodevelopmental defect.

Contains fulltext : 80657.pdf (publisher's version ) (Closed access), BACKGROUND: Recurrent 15q13.3 microdeletions were recently identified with identical proximal (BP4) and distal (BP5) breakpoints and associated with mild to moderate mental retardation and epilepsy. METHODS: To assess further the clinical implications of this novel 15q13.3 microdeletion syndrome, 18 new probands with a deletion were molecularly and clinically characterised. In addition, we evaluated the characteristics of a family with a more proximal deletion between BP3 and BP4. Finally, four patients with a duplication in the BP3-BP4-BP5 region were included in this study to ascertain the clinical significance of duplications in this region. RESULTS: The 15q13.3 microdeletion in our series was associated with a highly variable intra- and inter-familial phenotype. At least 11 of the 18 deletions identified were inherited. Moreover, 7 of 10 siblings from four different families also had this deletion: one had a mild developmental delay, four had only learning problems during childhood, but functioned well in daily life as adults, whereas the other two had no learning problems at all. In contrast to previous findings, seizures were not a common feature in our series (only 2 of 17 living probands). Three patients with deletions had cardiac defects and deletion of the KLF13 gene, located in the critical region, may contribute to these abnormalities. The limited data from the single family with the more proximal BP3-BP4 deletion suggest this deletion may have little clinical significance. Patients with duplications of the BP3-BP4-BP5 region did not share a recognisable phenotype, but psychiatric disease was noted in 2 of 4 patients. CONCLUSIONS: Overall, our findings broaden the phenotypic spectrum associated with 15q13.3 deletions and suggest that, in some individuals, deletion of 15q13.3 is not sufficient to cause disease. The existence of microdeletion syndromes, associated with an unpredictable and variable phenotypic outcome, will pose the clinician with diagnosti

Contains fulltext : 80578.pdf (publisher's version ) (Closed access), Microarray-based copy number analysis has found its way into routine clinical practice, predominantly for the diagnosis of patients with unexplained mental retardation. However, the clinical interpretation of submicroscopic copy number variants (CNVs) is complicated by the fact that many CNVs are also present in the general population. Here we introduce and discuss a workflow that can be used in routine diagnostics to assess the clinical significance of the CNVs identified. We applied this scheme to our cohort of 386 individuals with unexplained mental retardation tested using a genome-wide tiling-resolution DNA microarray and to 978 additional patients with mental retardation reported in 15 genome-wide microarray studies extracted from the literature. In our cohort of 386 patients we identified 25 clinically significant copy number losses (median size 2.6 Mb), nine copy number gains (median size 2.0 Mb), and one mosaic numerical chromosome aberration. Accordingly, the overall diagnostic yield of clinically significant CNVs was 9.1%. Taken together, our cohort and the patients described in the literature include a total of 1,364 analyses of DNA copy number in which a total of 11.2% (71.9% losses, 19.6% gains, 8.5% complex) could be identified, reflecting the overall diagnostic yield of clinically significant CNVs in individuals with unexplained mental retardation.

Contains fulltext : 80011.pdf (publisher's version ) (Closed access), In acute promyelocytic leukemia (APL), differentiation therapy with all-trans retinoic acid (ATRA) and/or arsenic trioxide can induce a differentiation syndrome (DS) with massive pulmonary infiltration of differentiating leukemic cells. Because chemokines are implicated in migration and extravasation of leukemic cells, chemokines might play a role in DS. ATRA stimulation of the APL cell line NB4 induced expression of multiple CC-chemokines (CCLs) and their receptors (> 19-fold), resulting in increased chemokine levels and chemotaxis. Induction of CCL2 and CCL24 was directly mediated by ligand-activated retinoic acid receptors. In primary leukemia cells derived from APL patients at diagnosis, ATRA induced chemokine production as well. Furthermore, in plasma of an APL patient with DS, we observed chemokine induction, suggesting that chemokines might be important in DS. Dexamethasone, which efficiently reduces pulmonary chemokine production, did not inhibit chemokine induction in APL cells. Finally, chemokine production was also induced by arsenic trioxide as single agent or in combination with ATRA. We propose that differentiation therapy may induce chemokine production in the lung and in APL cells, which both trigger migration of leukemic cells. Because dexamethasone does not efficiently reduce leukemic chemokine production, pulmonary infiltration of leukemic cells may induce an uncontrollable hyperinflammatory reaction in the lung.

Contains fulltext : 79652.pdf (publisher's version ) (Closed access), Genomic microarrays have been implemented in the diagnosis of patients with unexplained mental retardation. This method, although revolutionizing cytogenetics, is still limited to the detection of rare de novo copy number variants (CNVs). Genome-wide single nucleotide polymorphism (SNP) microarrays provide high-resolution genotype as well as CNV information in a single experiment. We hypothesize that the widespread use of these microarray platforms can be exploited to greatly improve our understanding of the genetic causes of mental retardation and many other common disorders, while already providing a robust platform for routine diagnostics. Here we report a detailed validation of Affymetrix 500k SNP microarrays for the detection of CNVs associated to mental retardation. After this validation we applied the same platform in a multicenter study to test a total of 120 patients with unexplained mental retardation and their parents. Rare de novo CNVs were identified in 15% of cases, showing the importance of this approach in daily clinical practice. In addition, much more genomic variation was observed in these patients as well as their parents. We provide all of these data for the scientific community to jointly enhance our understanding of these genomic variants and their potential role in this common disorder.

Contains fulltext : 80707.pdf (publisher's version ) (Closed access), Array CGH (comparative genomic hybridization) screening of large patient cohorts with mental retardation and/or multiple congenital anomalies (MR/MCA) has led to the identification of a number of new microdeletion and microduplication syndromes. Recently, a recurrent copy number variant (CNV) at chromosome 16p11.2 was reported to occur in up to 1% of autistic patients in three large autism studies. In the screening of 4284 patients with MR/MCA with various array platforms, we detected 22 individuals (14 index patients and 8 family members) with deletions in 16p11.2, which are genomically identical to those identified in the autism studies. Though some patients shared a facial resemblance and a tendency to overweight, there was no evidence for a recognizable phenotype. Autism was not the presenting feature in our series. The assembled evidence indicates that recurrent 16p11.2 deletions are associated with variable clinical outcome, most likely arising from haploinsufficiency of one or more genes. The phenotypical spectrum ranges from MR and/or MCA, autism, learning and speech problems, to a normal phenotype.

Contains fulltext : 80644.pdf (publisher's version ) (Closed access), Interstitial deletions of 7q11.23 cause Williams-Beuren syndrome, one of the best characterized microdeletion syndromes. The clinical phenotype associated with the reciprocal duplication however is not well defined, though speech delay is often mentioned. We present 14 new 7q11.23 patients with the reciprocal duplication of the Williams-Beuren syndrome critical region, nine familial and five de novo. These were identified by either array-based MLPA or by array-CGH/oligonucleotide analysis in a series of patients with idiopathic mental retardation with an estimated population frequency of 1:13,000-1:20,000. Variable speech delay is a constant finding in our patient group, confirming previous reports. Cognitive abilities range from normal to moderate mental retardation. The association with autism is present in five patients and in one father who also carries the duplication. There is an increased incidence of hypotonia and congenital anomalies: heart defects (PDA), diaphragmatic hernia, cryptorchidism and non-specific brain abnormalities on MRI. Specific dysmorphic features were noted in our patients, including a short philtrum, thin lips and straight eyebrows. Our patient collection demonstrates that the 7q11.23 microduplication not only causes language delay, but is also associated with congenital anomalies and a recognizable face.

Contains fulltext : 81737.pdf (publisher's version ) (Closed access), Genomic copy number variation (CNV) plays a major role in various human diseases as well as in normal phenotypic variability. For some recurrent disease-causing CNVs that convey genomic disorders, the causative mechanism is meiotic, non-allelic, homologous recombination between breakpoint regions exhibiting extensive sequence homology (e.g. low-copy repeats). For the majority of recently identified rare pathogenic CNVs, however, the mechanism is unknown. Recently, a model for CNV formation implicated mitotic replication-based mechanisms, such as (alternative) non-homologous end joining and fork stalling and template switching, in the etiology of human pathogenic CNVs. The extent to which such mitotic mechanisms contribute to rare pathogenic CNVs remains to be determined. In addition, it is unexplored whether genomic architectural features such as repetitive elements or sequence motifs associated with DNA breakage stimulate the formation of rare pathogenic CNVs. To this end, we have sequenced breakpoint junctions of 30 rare pathogenic microdeletions and eight tandem duplications, representing the largest series of such CNVs examined to date in this much detail. Our results demonstrate the presence of (micro)homology ranging from 2 to over 75 bp, in 79% of the breakpoint junctions. This indicates that microhomology-mediated repair mechanisms, including the recently reported fork stalling and template switching and/or microhomology-mediated break-induced replication, prevail in rare pathogenic CNVs. In addition, we found that the vast majority of all breakpoints (81%) were associated with at least one of the genomic architectural features evaluated. Moreover, 75% of tandem duplication breakpoints were associated with the presence of one of two novel sequence motifs. These data suggest that rare pathogenic microdeletions and tandem duplications do not occur at random genome sequences, but are stimulated and potentially catalyzed by various genomic architectural features

Contains fulltext : 79846.pdf (publisher's version ) (Closed access), In a man with severe mental retardation, minor facial and genital anomalies, disproportionate short stature and a broad thorax, we identified a de novo Xq13.2q21.1 duplication by array CGH. This 7 Mb duplication encompasses 23 known genes, including the X-linked mental retardation (XLMR) genes ATRX and SLC16A2. The phenotype of this patient is similar to that described in more than 10 previously reported patients with overlapping Xq duplications. Detailed comparison of the clinical characteristics and the function of the genes located in the commonly duplicated regions of these patients led us to the hypothesis that an increased dosage of ATRX and perhaps of other genes is involved in the pathogenetic mechanism of this XLMR phenotype, including mental retardation, short stature, and genital abnormalities comprising cryptorchidism and/or a small penis.

Contains fulltext : 81782.pdf (publisher's version ) (Closed access), Only two patients with 14q12 deletion have been reported to date. Here, we describe an additional patient with a similar deletion in order to improve the clinical delineation of this new microdeletion syndrome. The emerging phenotype is characterized by a Rett-like clinical course with an almost normal development during the first months of life followed by a period of regression. A peculiar facial phenotype is also present and it is characterized by mild dysmorphisms such as downslanting palpebral fissures, bilateral epicanthic folds, depressed nasal bridge, bulbous nasal tip, tented upper lip, everted lower lip and large ears. The relationship between this microdeletion syndrome and the congenital variant of Rett syndrome due to point mutations in one of the genes included in the deleted region, FOXG1, is discussed.

Contains fulltext : 71307.pdf (publisher's version ) (Closed access), Congenital pseudoarthrosis of the clavicle (CPC) has been described in several genetic conditions including Floating-Harbor and Goltz syndromes, but rarely as a prompt to specific cytogenetic abnormalities. We report on a case of a de novo 10p11.21p12.1 microdeletion in a boy with multiple problems including a beaten copper appearance of the cranium on skull X-ray and pseudoarthrosis of the right clavicle. This is the first description of these particular skeletal findings in the context of a chromosome 10p deletion.

Contains fulltext : 69539.pdf (publisher's version ) (Closed access), BACKGROUND: Patients with a microscopically visible deletion of the distal part of the long arm of chromosome 1 have a recognisable phenotype, including mental retardation, microcephaly, growth retardation, a distinct facial appearance and various midline defects including corpus callosum abnormalities, cardiac, gastro-oesophageal and urogenital defects, as well as various central nervous system anomalies. Patients with a submicroscopic, subtelomeric 1qter deletion have a similar phenotype, suggesting that the main phenotype of these patients is caused by haploinsufficiency of genes in this region. OBJECTIVE: To describe the clinical presentation of 13 new patients with a submicroscopic deletion of 1q43q44, of which nine were interstitial, and to report on the molecular characterisation of the deletion size. Results and CONCLUSIONS: The clinical presentation of these patients has clear similarities with previously reported cases with a terminal 1q deletion. Corpus callosum abnormalities were present in 10 of our patients. The AKT3 gene has been reported as an important candidate gene causing this abnormality. However, through detailed molecular analysis of the deletion sizes in our patient cohort, we were able to delineate the critical region for corpus callosum abnormalities to a 360 kb genomic segment which contains four possible candidate genes, but excluding the AKT3 gene.

Contains fulltext : 69185.pdf (publisher's version ) (Closed access)