The correlation between copy number variation in Chromosome 14 and DNA methylation in Saudi autistic children

S. Alhazmi, B. Aljahdli, R. Farsi, M. Alharbi, K. Algothmi, N. Alburae, M. Ganash, S. Azhari, F. Basingab, A. Almuhammadi, A. Alqosaibi, H. Alkhatabi, A. Elaimi, M. Jan, H. Aldhalaan, R. Alyoubi, A. Alrafiah, A. Alrofaidi

Department of Biological Sciences, King Abdulaziz University, Jeddah, Saudi Arabia. aalrafiah@kau.edu.sa

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• Genetics

OBJECTIVE: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that represents a range of aberrant behaviour symptoms such as repetitive behaviours and defects in social communication. The prevalence of ASD has been increasing worldwide and many studies have reported that both genetic and epigenetic factors play an important role in the etiology of this disorder. The aim of this study was to investigate the implementation of DNA methylation and Copy number variation (CNV) in the diagnosis of ASD.

PATIENTS AND METHODS: This study was carried out on 14 Saudi autistic children and four of their healthy siblings. Comparative genomic hybridization array was used to identify CNV in chromosome 14 and MethyLight qPCR was used to estimate levels of DNA methylation.

RESULTS: The results identified CNVs in six cytobands in chromosome 14 for 13 out of 14 autistic samples: 14q11.1-q11.2, 14q11.2, 14q12, 14q21.1, 14q32.2, and 14q32.33. However, some of these cytobands were also found in normal samples with different sizes. Interestingly, chromosomal abnormalities in 14q11.1-q11.2 was only found in ASD samples. The result also showed an increase in methylation ratio of ASD samples in those CNV regions compared with their siblings.

CONCLUSIONS: The findings suggest that CNV in 14q11.1-q11.2 might be a potential target in ASD diagnosis and further work is required to detect which biological pathways are affected.

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