PMC7154238_01
a Pedigree of a Vietnamese family with Meesmann corneal dystrophy. Individuals heterozygous for the KRT12 c.1273G>A variant are indicated by +/c.1273G>A and individuals who lack the mutation are indicated by +/+. The proband is indicated by a black arrow. b Sanger sequencing demonstrates that the KRT12 c.1273G>A (p.Glu425Lys) variant is present in the proband and all affected family members.
cop-0011-0120-g01.jpg
PMC7154238_01_cop-0011-0120-g01.jpg
F1
A 31-year-old Vietnamese man (Fig. 1a, II-2) presented to the Vietnam National Eye Hospital with a 1-year history of recurrent episodes of ocular irritation and frequent photophobia. Slit-lamp biomicroscopy of the proband's 56-year-old mother (Fig. 1a, I-2), who was diagnosed with cataract in both eyes and had counting fingers at 1 m visual acuity in each eye, revealed diffuse intraepithelial cysts extending from limbus to limbus in each eye (Fig. 2c). The proband's 35-year-old brother (Fig. 1a, II-1), who denied ocular complaints and had uncorrected visual acuity of 20/20 in both eyes, presented with diffuse intraepithelial cysts extending from limbus to limbus in each cornea (Fig. 2d), similar to his mother. The proband's 4-year-old daughter (Fig. 1a, III-1), for whom visual acuity testing could not be performed, also demonstrated bilateral diffusely distributed intraepithelial microcysts in both corneas. Screening of KRT12 exon 6 in 6 family members demonstrated segregation of the c.1273G>A variant with the affected phenotype, with its identification in the heterozygous state in three affected family members (Fig. 1a, individuals I:2, II:1, and III:1) and its absence in 3 unaffected family members (Fig. 1a, I:1, II:3, and III:2).
Slit-lamp images of the 31-year-old proband's cornea, showing intraepithelial cysts in the periphery of the cornea sparing the central corneal epithelium, seen with both direct (a) and indirect (b) illumination. The proband's 56-year-old mother (c) and 35-year-old brother (d) demonstrated diffuse intraepithelial corneal microcysts on retro-illumination.
cop-0011-0120-g02.jpg
PMC7154238_01_cop-0011-0120-g02.jpg
F2
A 31-year-old Vietnamese man (Fig. 1a, II-2) presented to the Vietnam National Eye Hospital with a 1-year history of recurrent episodes of ocular irritation and frequent photophobia. Slit-lamp biomicroscopy revealed numerous small, clear, confluent intraepithelial cysts confined to the peripheral cornea of each eye, with a clear boundary between the involved and normal epithelium (Fig. 2a, b). Slit-lamp biomicroscopy of the proband's 56-year-old mother (Fig. 1a, I-2), who was diagnosed with cataract in both eyes and had counting fingers at 1 m visual acuity in each eye, revealed diffuse intraepithelial cysts extending from limbus to limbus in each eye (Fig. 2c). Sanger sequencing of KRT3 (exon 7) and KRT12 (exons 1 and 6) in the proband (individual II:2) revealed a novel heterozygous c.1273G>A (p.Glu425Lys) variant in KRT12 exon 6 (Fig. 2b). Screening of KRT12 exon 6 in 6 family members demonstrated segregation of the c.1273G>A variant with the affected phenotype, with its identification in the heterozygous state in three affected family members (Fig. 1a, individuals I:2, II:1, and III:1) and its absence in 3 unaffected family members (Fig. 1a, I:1, II:3, and III:2).