Koolen-de Vries syndrome: A de novo missense KANSL1 variant

Koolen-de Vries syndrome is a rare genetic disorder marked by developmental and speech delays, intellectual disability, hypotonia, seizures, multiple congenital anomalies, and dysmorphic facial features. This syndrome is caused by microdeletions or loss-of-function mutations in the KANSL1 gene. KANSL1 encodes a nuclear protein that, via histone modification, regulates global transcription.

The patient was referred to our clinic due to a combination of intellectual disability, developmental delay, epilepsy, and dysmorphic facial features. A de novo missense heterozygous mutation c 0.1774 C > T (p.Arg592Trp) in the KANSL1 gene was discovered using trio whole exome sequencing.

This is the first case report of Koolen-de Vries syndrome in Turkey, to the best of our knowledge.