A Rare Pathogenic Frameshift Mutation in NSD1 Gene Related to Sotos Syndrome in a Turkish Patient

Abstract

Sotos syndrome which autosomal dominant inheritance has been observed, caused by the mutations and deletions in NSD1 gene. NSD1 gene consists 23 exons and localizes on chromosome 5q35.3. The prevalance of the Sotos syndrome is 1:14000 live births and the disease is characterized by excessive growth resulting in tall stature, a characteristical face appearance, advanced bone age, neurological disorder with intellectual disability and etc. Over 90% of the patients represent overgrowth, learning disability and macrocephaly. It has been shown that NSD1 gene mutations and microdeletions in 5q35.3 were common cause of Sotos syndrome. In this study we describe a 4 years old boy with Sotos syndrome harbouring a pathogenic NSD1 frameshift mutation. Clinical exome sequencing was performed using 2 ml of peripheral blood sample of the patient. The high-throughput data was analyzed using SOPHIA DDM database. The pathogenity of the mutations were evaluated based on in silico prediction tools (ClinVar, SIFT, Polyphen2, MutationTaster).We detected a pathogenic frameshift variant in NSD1 gene, 2386_2389delGAAA by clinical exome sequencing. Although the diagnosis of Sotos syndrome can be made clinically, molecular analyzes are also important in diagnosis. Numerious NSD1 gene mutations and deletions have been identified to date. However, 2386_2389delGAAA pathogenic variant in the NSD1 gene associated with Sotos syndrome will be reported for the first time in Turkey. Keywords: Sotos syndrome, NSD1, clinical exome sequencing