Investigation of Copy Number Variation by arrayCGH in Turkish Children and Adolescents Diagnosed with Autism Spectrum Disorders.

AIM: The development of whole-genome screening methodologies for the detection of copy number variations (CNVs), such as array-based comparative genomic hybridization (aCHG), provides a much higher resolution than karyotyping leading to the identification of novel microdeletion and microduplication syndromes often associated with an autism spectrum disease (ASD) phenotype. The aim of the study was to determine CNVs of patients with ASD by using array-based comparative genomic hybridization. METHODS: Fifty-three patients diagnosed with ASD between 20.01.2014 and 14.01.2015 were included in the study. Chromosome analysis of the patients was performed from peripheral blood cultures and analysed as normal. All patients were evaluated with P064C1 and P096A2 MLPA probes in terms of 16 mental retardation related syndromes. For aCGH method, SurePrint G3 Human microarrays 8x60K were used with genomic DNA isolated from peripheral blood. RESULTS: According to results of 53 patients who were included in and performed with arrayCGH, 8 (15%) patients had CNVs classified as pathogenic or variant of unknown significance (VOUS) in the study. We detected a pathogenic NRXN1 gene partial CNV deletion (2p16.3) in two patients. Also we identified a 900 kb duplication of 4p15.31 including SLIT2 gene, and a 245 kb duplication of 15q11.2 including PWRN1 gene in one patient. Our other findings are considered to be a variant of unknown significance (VOUS). CONCLUSION: The results of the study support the literature knowledge, where the copy number variations that cannot be detected with conventional cytogenetics methods in terms of size may happen in patients with ASD.

Novel EYA1 variants causing Branchio-oto-renal syndrome.

INTRODUCTION: Branchio-oto-renal (BOR) syndrome is an autosomal dominant genetic disorder characterized by second branchial arch anomalies, hearing impairment, and renal malformations. Pathogenic mutations have been discovered in several genes such as EYA1, SIX5, and SIX1. However, nearly half of those affected reveal no pathogenic variant by traditional genetic testing. METHODS AND MATERIALS: Whole Exome sequencing and/or Sanger sequencing performed in 10 unrelated families from Turkey, Iran, Ecuador, and USA with BOR syndrome in this study. RESULTS: We identified causative DNA variants in six families including novel c.525delT, c.979T > C, and c.1768delG and a previously reported c.1779A > T variants in EYA1. Two large heterozygous deletions involving EYA1 were detected in additional two families. Whole exome sequencing did not reveal a causative variant in the remaining four families. CONCLUSIONS: A variety of DNA changes including large deletions underlie BOR syndrome in different populations, which can be detected with comprehensive genetic testing.

Tetrasomy 18p in a Twin Pregnancy with Diverse Expression in Both Fetuses.

Tetrasomy 18p, characterized by the presence of four copies of the short arm of chromosome 18, is considered to occur with the nondisjunction in meiosis II after the errors in the meiotic and early postmeiotic mitotic division in the centromere. It is accompanied by various abnormalities including congenital heart defects, lower extremity abnormalities, micrognathia, high arched palate, kyphoscoliosis, microcephaly, myelomeningocele, hernia and renal anomalies. We present the first case of a dichorionic diamniotic twin pregnancy in which both fetuses were affected by tetrasomy 18p, but with discordant morphology, detected in one twin in the first but in the other in the second trimester.