Abstract

Background: Cockayne syndrome (CS) is a rare form of dwarfism that is characterized by progressive premature aging. The excision repair cross complementing protein group 6 (ERCC8) gene, which codes for the CS group A (CSA) protein, is usually mutated in cases of CS. Method: We show two Iranian families who have significant speech delay, microcephaly, developmental delay, and notable growth failure. We have discovered a unique homozygous missense variant (c.742G > T) in CSA in an Iranian family with CS, which we discovered using whole exome sequencing as well. Results: In two related probands, we found a homozygous variant (c.742G > T) in the ERCC8 gene that we believe to be a unique pathogenic mutation. Conclusion: WES results together with the characteristic clinical manifestations of Cockayne syndrome, provided an accurate diagnosis for two families. Also, our study identified novel variants in Iranian families.