SEVERE FORM OF JUVENILE CORNEAL STROMAL DYSTROPHY WITH HOMOZYGOUS R124H MUTATION IN THE KERATOEPITHELIN GENE IN 5 JAPANESE PATIENTS

Aim-To confirm the mutation of the keratoepithelin gene in patients wi th a severe form of superficial juvenile granular corneal dystrophy (G CD). Methods-Five Japanese probands in whom GCD was diagnosed after hi stopathological examination and who developed severe manifestations of GCD in their first decade of life were investigated. Other affected f amily members of two probands were also examined. All probands were th e offspring of consanguineous parents. DNA was extracted from their pe ripheral blood leucocytes and mutational analysis of the gene was perf ormed by the polymerase chain reaction and direct sequencing. Results- Four of the five probands underwent their first keratectomy or keratop lasty in their teens and subsequently underwent a second or third kera toplasty. Each proband had a homozygous G --> A transition at codon 12 4, replacing Arg --> His, of the keratoepithelin gene. Their moderatel y affected family members were heterozygous for the mutation. Conclusi ons-This finding suggests that the severity of the corneal phenotype d epends on the dose effect of the mutant gene.