Additional evidence for the role of chromosomal imbalances and SOX8, ZNRF3 and HHAT gene variants in early human testis development.

BACKGROUND: Forty-six ,XY Differences/Disorders of Sex Development (DSD) are characterized by a broad phenotypic spectrum ranging from typical female to male with undervirilized external genitalia, or more rarely testicular regression with a typical male phenotype. Despite progress in the genetic diagnosis of DSD, most 46,XY DSD cases remain idiopathic. METHODS: To determine the genetic causes of 46,XY DSD, we studied 165 patients of Tunisian ancestry, who presented a wide range of DSD phenotypes. Karyotyping, candidate gene sequencing, and whole-exome sequencing (WES) were performed. RESULTS: Cytogenetic abnormalities, including a high frequency of sex chromosomal anomalies (85.4%), explained the phenotype in 30.9% (51/165) of the cohort. Sanger sequencing of candidate genes identified a novel pathogenic variant in the SRY gene in a patient with 46,XY gonadal dysgenesis. An exome screen of a sub-group of 44 patients with 46,XY DSD revealed pathogenic or likely pathogenic variants in 38.6% (17/44) of patients. CONCLUSION: Rare or novel pathogenic variants were identified in the AR, SRD5A2, ZNRF3, SOX8, SOX9 and HHAT genes. Overall our data indicate a genetic diagnosis rate of 41.2% (68/165) in the group of 46,XY DSD.

Neuronal migration genes and a familial translocation t (3;17): candidate genes implicated in the phenotype.

BACKGROUND: While Miller-Dieker syndrome critical region deletions are well known delineated anomalies, submicroscopic duplications in this region have recently emerged as a new distinctive syndrome. So far, only few cases have been described overlapping 17p13.3 duplications. METHODS: In this study, we report on clinical and cytogenetic characterization of two new cases involving 17p13.3 and 3p26 chromosomal regions in two sisters with familial history of lissencephaly. Fluorescent In Situ Hybridization and array Comparative Genomic Hybridization were performed. RESULTS: A deletion including the critical region of the Miller-Dieker syndrome of at least 2,9 Mb and a duplication of at least 3,6 Mb on the short arm of chromosome 3 were highlighted in one case. The opposite rearrangements, 17p13.3 duplication and 3p deletion, were observed in the second case. This double chromosomal aberration is the result of an adjacent 1:1 meiotic segregation of a maternal reciprocal translocation t(3,17)(p26.2;p13.3). CONCLUSIONS: 17p13.3 and 3p26 deletions have a clear range of phenotypic features while duplications still have an uncertain clinical significance. However, we could suggest that regardless of the type of the rearrangement, the gene dosage and interactions of CNTN4, CNTN6 and CHL1 in the 3p26 and PAFAH1B1, YWHAE in 17p13.3 could result in different clinical spectrums.

Small supernumerary marker chromosomes (sSMC) and male infertility: characterization of five new cases, review of the literature, and perspectives.

PURPOSE: To characterize small supernumerary marker chromosomes (sSMC) in infertile males RESEARCH QUESTION: Are molecular cytogenetic methods still relevant for the identification and characterization of sSMC in the era of next-generation sequencing? METHODS: In this paper, we report five males with oligoasthenozoospermia or azoospermia with a history of recurrent pregnancy loss in partnership in four cases. R-banding karyotyping and fluorescence in situ hybridization (FISH) analysis were performed and showed sSMC in all five cases. Microdissection and reverse-FISH were performed in one case. RESULTS: One sSMC, each, was derived from chromosome 15 and an X-chromosome; two sSMC were derivatives of chromosome 22. The fifth sSMC was a ring chromosome 4 complemented by a deletion of the same region 4p14 to 4p16.1 in one of the normal chromosomes 4. All markers were mosaics except one of sSMC(22). CONCLUSION: Through this study, we emphasize the necessity of a proper combination of high-throughput techniques with conventional cytogenetic and FISH methods. This could provide a personalized diagnostic and accurate results for the patients suffering from infertility or RPL. We also highlight FISH analyses, which are essential tools for detecting sSMC in infertile patients. In fact, despite its entire composition of heterochromatin, sSMC can have effects on spermatogenesis by producing mechanical perturbations during meiosis and increasing meiotic nondisjunction rate. This would contribute to understand the exact chromosomal mechanism disrupting the natural and the assisted reproduction leading to offer a personalized support.

TCTN3 mutations cause Mohr-Majewski syndrome.

Orofaciodigital syndromes (OFDSs) consist of a group of heterogeneous disorders characterized by abnormalities in the oral cavity, face, and digits and associated phenotypic abnormalities that lead to the delineation of 13 OFDS subtypes. Here, by a combined approach of homozygozity mapping and exome ciliary sequencing, we identified truncating TCTN3 mutations as the cause of an extreme form of OFD associated with bone dysplasia, tibial defect, cystic kidneys, and brain anomalies (OFD IV, Mohr-Majewski syndrome). Analysis of 184 individuals with various ciliopathies (OFD, Meckel, Joubert, and short rib polydactyly syndromes) led us to identify four additional truncating TCTN3 mutations in unrelated fetal cases with overlapping Meckel and OFD IV syndromes and one homozygous missense mutation in a family with Joubert syndrome. By exploring roles of TCTN3 in human ciliary related functions, we found that TCTN3 is necessary for transduction of the sonic hedgehog (SHH) signaling pathway, as revealed by abnormal processing of GLI3 in patient cells. These results are consistent with the suggested role of its murine ortholog, which forms a complex at the ciliary transition zone with TCTN1 and TCTN2, both of which are also implicated in the transduction of SHH signaling. Overall, our data show the involvement of the transition zone protein TCTN3 in the regulation of the key SHH signaling pathway and that its disruption causes a severe form of ciliopathy, combining features of Meckel and OFD IV syndromes.

Genetic investigation of the ubiquitin-protein ligase E3A gene as putative target in Angelman syndrome.

BACKGROUND: Angelman syndrome (AS) is caused by maternal chromosomal deletions, imprinting defects, paternal uniparental disomy involving chromosome 15 and the ubiquitin-protein ligase UBE3A gene mutations. However the genetic basis remains unclear for several patients. AIM: To investigate the involvement of UBE3A gene in AS and identifying new potential genes using exome sequencing. METHODS: We established a cohort study in 50 patients referred to Farhat Hached University Hospital between 2006 and 2021, with a strong suspicion of AS and absence of chromosomal aberrations. The UBE3A gene was screened for mutation detection. Two unrelated patients issued from consanguineous families were subjected to exome analysis. RESULTS: We describe seven UBE3A variants among them 3 none previously described including intronic variants c.2220+14T>C (intron14), c.2507+43T>A (Exon15) and insertion in Exon7: c.30-47_30-46. The exome sequencing revealed 22 potential genes that could be involved in AS-like syndromes that should be investigated further. CONCLUSION: Screening for UBE3A mutations in AS patients has been proven to be useful to confirm the diagnosis. Our exome findings could rise to new potential alternative target genes for genetic counseling.

Anomalies in Human Sex Determination: Usefulness of a Combined Cytogenetic Approach to Characterize an Additional Case with Xp Functional Disomy Associated with 46,XY Gonadal Dysgenesis

Objective: Disorders of sexual development (DSD) are a heterogeneous group of genital defects affecting chromosomal, gonadal and anatomical sex. 46,XY DSD is a subset of DSD which covers a wide range of phenotypes in which 46,XY gonadal dysgenesis (GD) is the most severe form. In this study, we report on the clinical and molecular cytogenetic findings of a study on a Tunisian girl with the syndromic form of 46,XY DSD. Methods: This case was a phenotypic female patient having several congenital anomalies including growth retardation. Karyotype, fluorescence in situ hybridization and array Comparative Genome Hybridization (array CGH) were performed. Results: The proband exhibited a de-novo 46,X,der(Y) karyotype. Array CGH revealed a pathogenic 27.5Mb gain of an Xp21.2 chromosome segment leading to Xp functional disomy. No deletion was observed in the Y-chromosome. The duplicated region encompassed the NR0B1 (DAX1) and MAGEB genes, located within the dosage sensitive sex (DSS) reversal locus, known as promote genes responsible for human sex reversal and testis repression. The extra-dosage and interactions of these genes with different specific genes could result in the impairment of the male sex pathway. Over-dosage of KAL1 and IL1RAPL1 genes fall within the somatic features observed in the patient. Conclusion: To the best of our knowledge, we report on the fourth case of Xp21.2-pter duplication within Xp;Yp translocation associated with XY GD. Our findings suggest that when duplicated, the NR0B1 and MAGEB genes could be a major cause of XY GD. Therefore, we emphasize the usefulness of a combined cytogenetic approach in order to provide an accurate genetic diagnosis for those patients having syndromic XY DSD in a clinical setting.

Clinical and molecular characterization of 1q43q44 deletion and corpus callosum malformations: 2 new cases and literature review.

BACKGROUND: Corpus callosum malformations (CCM) represent one of the most common congenital cerebral malformations with a prevalence of around one for 4000 births. There have been at least 230 reports in the literature concerning 1q43q44 deletions of varying sizes discovered using chromosomal microarrays. This disorder is distinguished by global developmental delay, seizures, hypotonia, corpus callosum defects, and significant craniofacial dysmorphism. In this study, we present a molecular cytogenetic analysis of 2 Tunisian patients with corpus callosum malformations. Patient 1 was a boy of 3 years old who presented psychomotor retardation, microcephaly, behavioral problems, interventricular septal defect, moderate pulmonary stenosis, hypospadias, and total CCA associated with delayed encephalic myelination. Patient 2 was a boy of 9 months. He presented a facial dysmorphia, a psychomotor retardation, an axial hypotonia, a quadri pyramidal syndrome, a micropenis, and HCC associated with decreased volume of the periventricular white matter. Both the array comparative genomic hybridization and fluorescence in situ hybridization techniques were used. RESULTS: Array CGH analysis reveals that patient 1 had the greater deletion size (11,7 Mb) at 1q43. The same region harbors a 2,7 Mb deletion in patient 2. Here, we notice that the larger the deletion, the more genes are likely to be involved, and the more severe the phenotype is likely to be. In both patients, the commonly deleted region includes six genes: PLD5, AKT3, ZNF238, HNRNPU, SDCCAG8 and CEP170. Based on the role of the ZNF238 gene in neuronal proliferation, migration, and cortex development, we hypothesized that the common deletion of ZNF238 in both patients seems to be the most responsible for corpus callosum malformations. Its absence may directly cause CCM. In addition, due to their high expression in the brain, PLD5 and FMN2 could modulate in the CCM phenotype. CONCLUSION: Our findings support and improve the complex genotype-phenotype correlations previously reported in the 1qter microdeletion syndrome and define more precisely the neurodevelopmental phenotypes associated with genetic alterations of several genes related to this pathology.

Case report: 7p22.3 deletion and 8q24.3 duplication in a patient with epilepsy and psychomotor delay-Does both possibly act to modulate a candidate gene region for the patient's phenotype?

Background: Psychomotor delay, epilepsy and dysmorphic features are clinical signs which are described in multiple syndromes due to chromosomal imbalances or mutations involving key genes implicated in the stages of Early Embryonic Development. In this context, we report a 10 years old Tunisian patient with these three signs. Our objective is to determine the cause of developmental, behavioral and facial abnormalities in this patient. Methods: We used banding cytogenetics (karyotype) and Array Comparative Genomic Hybridization (Array CGH) to this purpose. Results: The karyotype was in favor of a derivative of chromosome 7 in the patient and Array CGH analysis revealed a loss of genetic material in 7p22.3-p22.1 (4,56 Mb) with a gain at 8q24.23-q24 (9.20 Mb) resulting from maternal 7/8 reciprocal translocation. An in silico analysis of the unbalanced region was carried out and showed that the 7p22.3-p22.1 deletion contains eight genes. Among them, BRAT1 gene, previously described in several neurodevelopmental diseases, may be a candidate gene which absence could be correlated to the patient's phenotype. However, the 8q24.23-q24 duplication could be involved in the phenotype of this patient. Conclusion: In this study, we report for the first time a 7p deletion/8q duplication in a patient with psychomoteur delay, epilepsy and facial dysmorphism. Our study showed that Array CGH still useful for delivering a conclusive genetic diagnosis for patients having neurodevelopmental abnormalities in the era of next-generation sequencing.

BBS10 mutations are common in 'Meckel'-type cystic kidneys.

BACKGROUND: Bardet-Biedl syndrome (BBS) is a genetically heterogeneous, multisystemic disorder characterised by progressive retinal dystrophy, obesity, hypogenitalism, learning difficulties, renal abnormalities and postaxial polydactyly, with only the last two antenatally observable. BBS is inherited as an autosomal recessive disorder, and 14 genes have been identified to date (BBS1-BBS14). In addition, a complex digenic inheritance has been established in some families. Mutations of the BBS10 gene on chromosome 12q21.2 account for 20% of BBS cases. METHODS: Given the fact that mutations in BBS genes have already been found in Meckel-like fetuses, and in light of the major contribution of BBS10 to BBS, the BBS10 gene was sequenced in 20 fetal cases and a child diagnosed antenatally presenting with characteristic renal anomalies and polydactyly, but without biliary dysgenesis. RESULTS: Recessive mutations were identified at the BBS10 locus in five cases: four fetuses and a child. Interestingly, one of them had situs ambiguus, a rare feature in BBS. In the child, BBS gene screening identified a heterozygous BBS6 nonsense mutation in addition to the homozygous BBS10 mutation, in accordance with the suggested multigenic inheritance of the disease. CONCLUSIONS: These results confirm that BBS is underdiagnosed antenatally and should systematically be suspected in fetuses with severe cystic kidneys leading to oligoamnios and fetal or perinatal death. Moreover, this study confirms the high frequency of BBS10 mutations, particularly of the p.Cys91LeufsX5 allele, including severe lethal cases.

Detection of aneuploidy rate for chromosomes X, Y and 8 by fluorescence in-situ hybridization in spermatozoa from patients with severe non-obstructive oligozoospermia.

PURPOSE: To evaluate the frequency of sperm nuclei disomy for chromosomes 8, X, and Y in patients with severe non-obstructive oligozoospermia and to assess possible correlations between sperm nuclei aneuploidy and semen parameters or a particular clinical phenotype. MATERIALS AND METHODS: The sperm aneuploidy rate for chromosomes X, Y, and 8 were assessed in 16 infertile men with severe non-obstructive oligozoospermia and 7 healthy men with normal semen parameters. The frequency of sperm aneuploidy was compared between several patients groups according to their clinical and biological factors. RESULTS: The total rate of chromosomally abnormal spermatozoa was significantly higher in patients with severe oligozoospermia compared to control group (P < 0.001). A significant relationship was found between the age of patients, sperm concentration, and morphology and the mean rate of sex chromosomes disomy. In addition to the low sperm count (<5 × 10(6)/ml), an elevated FSH level and an exposed to an elevated temperature are two major predictive factors leading to the production of higher numbers of chromosomally abnormal gametes. CONCLUSION: Patients with severe oligozoospermia, who are potential candidates for assisted reproduction technology, presented a high level of sex numerical chromosome abnormalities, and consequently are at high risk of chromosome abnormalities in their offspring.

Further report of MEDS syndrome: Clinical and molecular delineation of a new Tunisian case.

Recently, an autosomal recessive disorder including the triad of microcephaly, infantile epileptic encephalopathy, and permanent neonatal diabetes syndrome (MEDS, OMIM#614231) has emerged as a new distinguishing syndrome. Eight cases of whom seven from Arab countries, have been reported in association with biallelic variants in the IER3IP1 gene (Immediate early response-3 interacting protein-1). Here, we describe a Tunisian boy who presented with permanent neonatal diabetes, microcephaly, generalized seizures and hypovirilized external genitalia consisting of a small genitalia and unilateral cryptorchidism. Chromosomal analysis indicated a 46, XY karyotype in all metaphases. Exome sequencing identified a homozygous missense variant (c.62 T > G; p. Val21Gly) in the IER3IP1 gene, that is predicted to alter the protein structure within the hydrophobic/transmembrane. This variant was previously reported in two cases associated with MEDS. This is the first reported case of MEDS in Tunisia. Our report focuses on the IER3IP1 related phenotypic spectrum and assumes abnormal genitalia as part of the syndrome. Consequently, we recommend to perform hormonal testing on this topic to understand the effect of the IER3IP1 variant on the male genital pathway.

Disorders of sex development in Wolf-Hirschhorn syndrome: a genotype-phenotype correlation and MSX1 as candidate gene.

BACKGROUND: Wolf-Hirschhorn (WHS) is a set of congenital physical anomalies and mental retardation associated with a partial deletion of the short arm of chromosome 4. To establish a genotype-phenotype correlation; we carried out a molecular cytogenetic analysis on two Tunisian WHS patients. Patient 1 was a boy of 1-year-old, presented a typical WHS phenotype while patient 2, is a boy of 2 days presented an hypospadias, a micropenis and a cryptorchidie in addition to the typical WHS phenotype. Both the array comparative genomic hybridization and fluorescence in situ hybridization techniques were used. RESULTS: Results of the analysis showed that patient 2 had a greater deletion size (4.8 Mb) of chromosome 4 than patient 1 (3.4 Mb). Here, we notice that the larger the deletion, the more genes are likely to be involved, and the more severe the phenotype is likely to be. If we analyze the uncommon deleted region between patient1 and patient 2 we found that the Muscle Segment Homeobox (MSX1) gene is included in this region. MSX1 is a critical transcriptional repressor factor, expressed in the ventral side of the developing anterior pituitary and implicated in gonadotrope differentiation. Msx1 acts as a negative regulatory pituitary development by repressing the gonadotropin releasing hormone (GnRH) genes during embryogenesis. We hypothesized that the deletion of MSX1 in our patient may deregulate the androgen synthesis. CONCLUSION: Based on the MSX1 gene function, its absence might be indirectly responsible for the hypospadias phenotype by contributing to the spatiotemporal regulation of GnRH transcription during development.

High-throughput sequencing of a 4.1 Mb linkage interval reveals FLVCR2 deletions and mutations in lethal cerebral vasculopathy.

Rare lethal disease gene identification remains a challenging issue, but it is amenable to new techniques in high-throughput sequencing (HTS). Cerebral proliferative glomeruloid vasculopathy (PGV), or Fowler syndrome, is a severe autosomal recessive disorder of brain angiogenesis, resulting in abnormally thickened and aberrant perforating vessels leading to hydranencephaly. In three multiplex consanguineous families, genome-wide SNP analysis identified a locus of 14 Mb on chromosome 14. In addition, 280 consecutive SNPs were identical in two Turkish families unknown to be related, suggesting a founder mutation reducing the interval to 4.1 Mb. To identify the causative gene, we then specifically enriched for this region with sequence capture and performed HTS in a proband of seven families. Due to technical constraints related to the disease, the average coverage was only 7×. Nonetheless, iterative bioinformatic analyses of the sequence data identified mutations and a large deletion in the FLVCR2 gene, encoding a 12 transmembrane domain-containing putative transporter. A striking absence of alpha-smooth muscle actin immunostaining in abnormal vessels in fetal PGV brains, suggests a deficit in pericytes, cells essential for capillary stabilization and remodeling during brain angiogenesis. This is the first lethal disease-causing gene to be identified by comprehensive HTS of an entire linkage interval.

Novel TMEM67 mutations and genotype-phenotype correlates in meckelin-related ciliopathies.

Human ciliopathies are hereditary conditions caused by defects of proteins expressed at the primary cilium. Among ciliopathies, Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS) and nephronophthisis (NPH) present clinical and genetic overlap, being allelic at several loci. One of the most interesting gene is TMEM67, encoding the transmembrane protein meckelin. We performed mutation analysis of TMEM67 in 341 probands, including 265 JSRD representative of all clinical subgroups and 76 MKS fetuses. We identified 33 distinct mutations, of which 20 were novel, in 8/10 (80%) JS with liver involvement (COACH phenotype) and 12/76 (16%) MKS fetuses. No mutations were found in other JSRD subtypes, confirming the strong association between TMEM67 mutations and liver involvement. Literature review of all published TMEM67 mutated cases was performed to delineate genotype-phenotype correlates. In particular, comparison of the types of mutations and their distribution along the gene in lethal versus non lethal phenotypes showed in MKS patients a significant enrichment of missense mutations falling in TMEM67 exons 8 to 15, especially when in combination with a truncating mutation. These exons encode for a region of unknown function in the extracellular domain of meckelin.

CC2D2A mutations in Meckel and Joubert syndromes indicate a genotype-phenotype correlation.

Meckel-Gruber syndrome (MKS) is a lethal fetal disorder characterized by diffuse renal cystic dysplasia, polydactyly, a brain malformation that is usually occipital encephalocele, and/or vermian agenesis, with intrahepatic biliary duct proliferation. Joubert syndrome (JBS) is a viable neurological disorder with a characteristic "molar tooth sign" (MTS) on axial images reflecting cerebellar vermian hypoplasia/dysplasia. Both conditions are classified as ciliopathies with an autosomal recessive mode of inheritance. Allelism of MKS and JBS has been reported for TMEM67/MKS3, CEP290/MKS4, and RPGRIP1L/MKS5. Recently, one homozygous splice mutation with a founder effect was reported in the CC2D2A gene in Finnish fetuses with MKS, defining the 6th locus for MKS. Shortly thereafter, CC2D2A mutations were also reported in JBS. The analysis of the CC2D2A gene in our series of MKS fetuses, identified 14 novel truncating mutations in 11 cases. These results confirm the involvement of CC2D2A in MKS and reveal a major contribution of CC2D2A to the disease. We also identified three missense CC2D2A mutations in two JBS cases. Therefore, and in accordance with the data reported regarding RPGRIP1L, our results indicate phenotype-genotype correlations, as missense and presumably hypomorphic mutations lead to JBS while all null alleles lead to MKS.

Clinical and molecular findings in nine new cases of tetrasomy 18p syndrome: FISH and array CGH characterization.

BACKGROUND: Small Supernumerary Marker Chromosomes (sSMC) are rare chromosomal abnormalities, which have abnormal banding arrangement and take many shapes. Several disorders have been correlated with sSMC presence. The aim of this study is to characterize the sSMC derived from chromosome 18 by Fluorescence in situ hybridization (FISH) and Array Comparative Genomic Hybridization (aCGH). RESULTS: Nine children with dysmorphic features have been investigated. They have these features in common: a triangular face, low-set ears, a large mouth with a thin upper lip, and a horizontal palpebral fissure. Epicanthus and strabismus were present in two patients. In addition, we have noticed microcephaly and mental and/or developmental delay with low birth weight. However, two patients had standard birth weight; one patient had hypospadias; two had skin problems; and three showed different congenital heart defects. One patient had corpus callosum hypoplasia. Systematic karyotype analysis revealed a de novo supernumerary chromosome. Array CGH showed a gain in copy number on the short arm of chromosome 18 in the nine cases. In one case, the sSMC seemed to be in mosaic. The breakpoints of the marker were identified using aCGH and FISH. Thus, the sSMC led to 18p tetrasomy with approximately 14 Mb lengths, between 364344 and 14763575 based on the human genome version 18. CONCLUSIONS: These results have been completed by FISH in order to ascertain the shape of the sSMC. Our results confirm the uniqueness and particularity of the iso18p syndrome on the phenotypic as well as on the genetic level.

Subtelomeric Rearrangements in Patients with Recurrent Miscarriage.

BACHGROUND: The subtelomeric rearrangements are increasingly being investigated in cases of idiopathic intellectual disabilities (ID) and congenital abnormalities (CA) but are also thought to be responsible for unexplained recurrent miscarriage (RM). Such rearrangements can go unnoticed through conventional cytogenetic techniques and are undetectable even with high-resolution molecular cytogenetic techniques such as array comparative genomic hybridization (aCGH), especially when DNA of the stillbirth or families are not available. The aim of the study is to evaluate the rate of subtelomeric rearrangements in patients with RM. MATERIALS AND METHODS: In this cross-sectional study, fluorescent in situ hybridization (FISH), based on ToTelVysion telomeric probes, was undertaken for 21 clinically normal couples exhibiting a "normal" karyotype with at least two abortions. Approximately 62% had RM with a history of stillbirth or CA/ID while the other 38% had only RM. RESULTS: FISH detected one cryptic rearrangement between chromosomes 3q and 4p in the female partner of a couple (III:4) [46,XX,ish t(3;4)(q28-,p16+;p16-,q28+)(D3S4559+,D3S4560-,D4S3359+; D3S4560+, D4S3359- ,D4S2930+)] who presented a history of RM and family history of ID and CA. Analysis of the other family members of the woman showed that her sisters (III:6 and III:11) and brother (III:8) were also carriers of the same subtelomeric translocation t(3;4)(q28;p16). CONCLUSION: We conclude that subtelomeric FISH should be undertaken in couples with RM especially those who not only have abortions but also have had at least one child with ID and/or CA, or other clinically recognizable syndromes. For balanced and cryptic anomalies, subtelomeric FISH still remains the most suitable and effective tool in characterising such chromosomal rearrangements in RM couples.

Array Characterization of Prenatally Diagnosed 15q26 Microdeletion and 2q37.1 Duplication: Report of a New Case with Multicystic Kidneys and Review of the Literature.

We report on a molecular cytogenetic characterization of 15q26 deletion and 2q37.1 duplication in a fetus presenting with intrauterine growth restriction (IUGR), diaphragmatic hernia, multicystic kidneys, left kidney pyelectasis, and clubfeet. A terminal 15q26 deletion and a terminal 2q duplication of at least 10 and 9 Mb, respectively, derived from a maternal translocation, were found. The 15q26 deletion represents a contiguous gene deletion syndrome mainly characterized by IUGR, congenital diaphragmatic hernia, and less frequently kidney defects. This deletion encompasses the IGF1R and COUPTF2 genes, known to lead to fetal growth retardation syndrome. However, kidney malformations are less well known in such conditions, and to the best of our knowledge, no candidate gene has been proposed to date. Here, we review the literature of the 15q26 deletion syndrome and suggest that hypoplastic and multicystic kidneys, the most commonly observed anomalies in this condition, should be considered in the prenatal diagnosis setting. Based on COUPTF2 protein function, we hypothesize that its haploinsufficiency might be responsible for the renal pathology.

Genomic Microarray in Intellectual Disability: The Usefulness of Existing Systems in the Interpretation of Copy Number Variation.

Whole genome array technology is an essential tool for the detection of a large number of copy number variants (CNVs) in patients with ID and/or multiple congenital anomalies. However, the clinical significance of some microimbalances is not known. In this article, we succeeded to detect seven new variations of unknown significance (dup12p13.33, dup2p16.3, dupXq13.2, del12q24.33, dup16p13.11, trip4q22.1, and dup9p21.3), one CNV classified as known pathogenic syndrome (del22q13.31-q33), and one CNV classified as potentially pathogenic (del11q24.3). We emphasize the role of comparative genomic hybridization arrays in the investigation of intellectual disability and evaluate the usefulness of existing systems in the interpretation of CNVs.