Intellectual disability (ID) is characterized by limited mental ability and adaptive behavior that imposes a heavy burden on the patients' families and the health care system. This study was aimed at determining the molecular aspect of nonsyndromic ID, in a family from South Khorasan Province in Iran. Exome sequencing was performed, as well as complete clinical examinations of the family. Afterward, in silico studies have been done to examine the changes that occurred in the protein structure, in association with the ID phenotype. The PIGG (NC_000004.12) mutation was found on Chr 4:517639G>A, and this chromosomal location was proposed as the disorder-causing variant. This Arg658Gln alteration was confirmed by Sanger sequencing, using specific primers for PIGG. In conclusion, our study indicated a novel mutation in the PIGG in the affected family. This mutation is a novel variant (p. R658Q) with an autosomal recessive inheritance pattern. These findings could improve genetic counseling in the future.
Keywords: In silico; Intellectual disability; South Khorasan; Whole-exome sequencing.