A Girl with Pervasive Developmental Disorder and Complex Chromosome Rearrangement Involving 8p and 10p

A Novel 1.0 Mb Duplication of Chromosome 8p22-21.3 in a Patient With Autism Spectrum Disorder

Autism spectrum disorders are a group of neurodevelopmental disorders with a strong genetic etiology. Cytogenetic abnormalities have been detected in 5% to 10% of the patients with autism spectrum disorders. In this study, the authors present the clinical and array-based comparative genomic hybridization evaluation of a 4-year-old male with autism spectrum disorder and mental retardation. The patient was found to carry a de novo duplication of chromosome 8p22-21.3 of 1.0 Mb as ascertained by quantitative polymerase chain reaction, and this region encompassed 3 genes including Pleckstrin and Sec7 domains-containing protein 3 (PSD3), SH2 domain-containing 4A (SH2D4A), and Chondroitin Sulfate N-Acetylgalactosaminyltransferase 1 (CSGALNACT1). This represents the smallest rearrangement of chromosome 8p as yet found in a patient with autism spectrum disorder, but the significance of this mutation is still ambiguous.

Genome-scan for IQ discrepancy in autism: evidence for loci on chromosomes 10 and 16

Performance IQ (PIQ) greater than verbal IQ (VIQ) is often observed in studies of the cognitive abilities of autistic individuals. This characteristic is correlated with social and communication impairments, key parts of the autism diagnosis. We present the first genetic analyses of IQ discrepancy (PIQ-VIQ) as an autism-related phenotype. We performed genome-wide joint linkage and segregation analyses on 287 multiplex families, using a Markov chain Monte Carlo approach. Genetic data included a genome-scan of 387 micro-satellite markers in 210 families augmented with additional markers added in a subset of families. Empirical P values were calculated for five interesting regions. Linkage analysis identified five chromosomal regions with substantial regional evidence of linkage; 10p12 [P = 0.001; genome-wide (gw) P = 0.05], 16q23 (P = .015; gw P = 0.53), 2p21 (P = 0.03, gw P = 0.78), 6q25 (P = 0.047, gw P = 0.91) and 15q23-25 (P = 0.053, gw P = 0.93). The location of the chromosome 10 linkage signal coincides with a region noted in a much earlier genome-scan for autism, and the chromosome 16 signal coincides exactly with a linkage signal for non-word repetition in specific language impairment. This study provides strong evidence for a QTL influencing IQ discrepancy in families with autistic individuals on chromosome 10, and suggestive evidence for a QTL on chromosome 16. The location of the chromosome 16 signal suggests a candidate gene, CDH13, a T-cadherin expressed in the brain, which has been implicated in previous SNP studies of autism and ADHD.

Chromosome 8p as a potential hub for developmental neuropsychiatric disorders: implications for schizophrenia, autism and cancer

Defects in genetic and developmental processes are thought to contribute susceptibility to autism and schizophrenia. Presumably, owing to etiological complexity identifying susceptibility genes and abnormalities in the development has been difficult. However, the importance of genes within chromosomal 8p region for neuropsychiatric disorders and cancer is well established. There are 484 annotated genes located on 8p; many are most likely oncogenes and tumor-suppressor genes. Molecular genetics and developmental studies have identified 21 genes in this region (ADRA1A, ARHGEF10, CHRNA2, CHRNA6, CHRNB3, DKK4, DPYSL2, EGR3, FGF17, FGF20, FGFR1, FZD3, LDL, NAT2, NEF3, NRG1, PCM1, PLAT, PPP3CC, SFRP1 and VMAT1/SLC18A1) that are most likely to contribute to neuropsychiatric disorders (schizophrenia, autism, bipolar disorder and depression), neurodegenerative disorders (Parkinson's and Alzheimer's disease) and cancer. Furthermore, at least seven nonprotein-coding RNAs (microRNAs) are located at 8p. Structural variants on 8p, such as copy number variants, microdeletions or microduplications, might also contribute to autism, schizophrenia and other human diseases including cancer. In this review, we consider the current state of evidence from cytogenetic, linkage, association, gene expression and endophenotyping studies for the role of these 8p genes in neuropsychiatric disease. We also describe how a mutation in an 8p gene (Fgf17) results in a mouse with deficits in specific components of social behavior and a reduction in its dorsomedial prefrontal cortex. We finish by discussing the biological connections of 8p with respect to neuropsychiatric disorders and cancer, despite the shortcomings of this evidence.

Molecular cytogenetic investigation of a balanced complex chromosomal rearrangement carrier ascertained through a neonate with partial trisomies of 13 and 22

Complex chromosomal rearrangement (CCR) is a structural abnormality of chromosomes that rarely appears in individuals with normal phenotypes. A CCR involving chromosomes 9, 13, and 22 was ascertained in a phenotypically normal woman through a neonate with multiple congenital malformations and partial trisomies of 13 and 22. We diagnosed the CCR using high-resolution chromosome analysis and three-color fluorescence in situ hybridization (three-color FISH) analysis, and ascertained a balanced CCR without cryptic imbalances using array comparative genomic hybridization (array CGH) and FISH. In the present work, we report on the case together with a literature review.

Unbalanced inherited complex chromosome rearrangement involving chromosome 8, 10, 11 and 16 in a patient with congenital malformations and delayed development

Complex chromosome rearrangements (CCR) are rare structural chromosome aberrations that can be found in patients with phenotypic abnormalities or in phenotypically normal patients presenting, however, recurrent miscarriages or infertility. Conventional karyotype generally allows their identification. However, molecular cytogenetic methods can reveal subtle rearrangements. We report, here, the identification of an unbalanced maternally inherited CCR in a boy with multiple congenital malformations and delayed development. High-resolution karyotype completed by molecular cytogenetic prompted us to precise the rearrangements. The healthy mother was found to carry a balanced de novo CCR that implicates four chromosomes (8, 10, 11 and 16), six breakpoints, three translocations and an insertion. The malsegregation of this CCR had led, in her son, to partial 10p12.3 to 10p14 deletion, a chromosomal region associated with the DiGeorge like phenotype.