Investigation of Submicroscopic Chromosomal Anomalies on Patients with Unexplained Intellectual Disabilities with Molecular Karyotyping

Açıklanamayan Entellektüel Yetersizliği Bulunan Hastalarda Moleküler Karyotipleme

Abstract

Backround: Intellectual disabilities, developmental delay and accompanying congenital anomalies are rarely seen on general population, but have a large etiologic spectrum. Chromosomal abnormalities are one of the significant reasons of intellectual disabilities, dysmorphic appearance and various congenital anomalies. Conventional cytogenetic techniques can only detect abnormalities greater than 5 Mb. Array based methods can be useful to detect anomalies smaller than 3 Mb to kilobase levels with a ratio of 12-14%. As a result, small interstitial deletions and duplications could be detected and new genes could be discovered with microarray techniques.

Methods: In this study, 29 patients with idiopathic intellectual disability, developmental delay and/or congenital anomaly, had been investigated for small deletions or duplications with “Array CGH 8x60K ISCA”.

Results: Causative/ probably causative pathology was detected in 6 patients and the diagnostic power of these systems was confirmed, and we obtained a yield of 20.6%. Feingold syndrome 1, Williams syndrome with atypical findings, 14q11.2 deletion syndrome and 1p36 deletion syndrome, 13q14.3-q21.1 duplication spanning PCDH17 gene and a duplication in Xp11.4 chromosomal region containing ATP6AP2 gene were detected. We reported second Feingold syndrome with renal agenesis and first case of 14q11.2 deletion syndrome with episodic vomitting attacks.

Conclusion: Microarray technology is the first-tier diagnostic method in patients with intellectual disability with multiple congenital anomalies. The genotype-phenotype correlation studies provide explaining the etiology and molecular mechanism of intellectual disability and developmental delay.