Disruption of PCDH10 and TNRC18 Genes due to a Balanced Translocation.

Balanced chromosomal rearrangements are usually associated with a normal phenotype, although in some individuals, phenotypic alterations are observed. In these patients, molecular characterization of the breakpoints can reveal the pathogenic mechanism, providing the annotation of disease-associated loci and a better genotype-phenotype correlation. In this study, we describe a patient with a balanced reciprocal translocation between 4q27 and 7p22 associated with neurodevelopmental delay. We performed cytogenetic evaluation, next-generation sequencing of microdissected derivative chromosomes, and Sanger sequencing of the junction points to define the translocation's breakpoints at base pair resolution. We found that the PCDH10 and TNRC18 genes were disrupted by the breakpoints at chromosomes 4 and 7, respectively, with the formation of chimeric genes at the junction points. Gene expression studies in the patient's peripheral blood showed reduced expression of TNRC18, a gene with unknown function and clinical significance. PCDH10 plays a role in the development of the nervous system and might be involved with the patient's neurodevelopmental delay. In this study, the full molecular characterization of the junction points was shown as an efficient tool for fine breakpoint mapping in balanced translocations in order to unmask gene disruptions and investigate the potential pathogenic role of the disrupted genes.

Malan syndrome in a patient with 19p13.2p13.12 deletion encompassing NFIX and CACNA1A genes: Case report and review of the literature.

BACKGROUND: Malan syndrome is a recently introduced overgrowth disorder described in a limited number of individuals. Haploinsufficiency and also point mutations of NFIX gene have been proposed as its leading causative mechanism, however, due to the limited number of cases and different deletion sizes, genotype/phenotype correlations are still limited. METHODS: Here, we report the first Brazilian case of Malan syndrome caused by a 990 kb deletion in 19p13.2p13.12, focusing on clinical and behavioral aspects of the syndrome. RESULTS: The patient presented with macrocephaly, facial dysmorphisms, hypotonia, developmental delay, moderate thoracolumbar scoliosis, and seizures. The intellectual and behavioral assessments showed severe cognitive, language, and adaptive functions impairments. The 19p deleted region of our patient encompasses NFIX, CACNA1A, which seems to be related to a higher frequency of seizures among individuals with microdeletions in 19p13.2, and 15 other coding genes, including CC2D1A and NACC1, both known to be involved in neurobiological process and pathways. CONCLUSION: Deletions involving NFIX gene should be considered in patients with overgrowth during childhood, macrocephaly, developmental delay, and seizures, as well as severe intellectual disability.

Marfan syndrome with a complex chromosomal rearrangement including deletion of the FBN1 gene.

BACKGROUND: The majority of Marfan syndrome (MFS) cases is caused by mutations in the fibrillin-1 gene (FBN1), mapped to chromosome 15q21.1. Only few reports on deletions including the whole FBN1 gene, detected by molecular cytogenetic techniques, were found in literature. RESULTS: We report here on a female patient with clinical symptoms of the MFS spectrum plus craniostenosis, hypothyroidism and intellectual deficiency who presents a 1.9 Mb deletion, including the FBN1 gene and a complex rearrangement with eight breakpoints involving chromosomes 6, 12 and 15. DISCUSSION: This is the first report of MFS with a complex chromosome rearrangement involving a deletion of FBN1 and contiguous genes. In addition to the typical clinical findings of the Marfan syndrome due to FBN1 gene haploinsufficiency, the patient presents features which may be due to the other gene deletions and possibly to the complex chromosome rearrangement.

Pure duplication 1q41-qter: further delineation of trisomy 1q syndromes.

Several authors have attempted to characterize the partial 1q trisomy syndrome, reporting clinical features such as mental retardation, macrocephaly, large fontanels, prominent forehead, broad flat nasal bridge, high-arched palate, micro/retrognathia, low-set ears, and cardiac defects. However, defining the partial trisomy 1q syndrome is difficult, because it is a rare chromosomal abnormality and in most instances the trisomy 1q is combined with partial monosomy of another autosomal segment. We report on the clinical and molecular cytogenetic study of a patient who presents pure partial 1q duplication. This is the first case of pure duplication 1q41-qter in the literature.