Purpose: To identify the genetic defect in the M1S1 gene causing gelatinous droplike corneal dystrophy (GDLD) in an Estonian family.
Methods: DNA was extracted from members of a GDLD-affected family and control persons. Polymerase chain reaction followed by direct sequencing was used to detect mutations in the M1S1 gene. Sequencing results were confirmed with restriction analysis.
Results: Sequencing of the M1S1 gene revealed a novel mutation and a common polymorphism. All patients with GDLD were found to be homozygous for the insertion of nucleotide C in position 520 in M1S1. The mutation leads to formation of truncated protein. The mutation was excluded in 103 normal, unaffected individuals. Very close to the location where the mutation was identified in the M1S1 gene, a single-nucleotide polymorphism (518A/C) was found, changing aspartic acid to alanine at codon 173.
Conclusions: The data indicate that mutation ins520C in the M1S1 gene is the primary cause of GDLD in the family studied.