PMC2573734_01
Slit lamp photographs of proband. The photographs of the proband (IV:25) showed that the opacities were lamellar cataracts.
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Other eye examinations included mydriasis later, slit lamp biological microscopy, and performance of the congenital lamellar cataracts (Figure 1).
Pedigree and haplotype of cataract family. Four-generation pedigree, with autosomal dominant lamellar cataracts. Haplotyping shows segregation of two microsatellite markers on 3q21-q25. Squares and circles indicate males and females, respectively. Blackened symbols and bars denote affected status.
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This four-generation family included 17 affected individuals with congenital lamellar cataracts and 56 unaffected individuals (Figure 2). Haplotype analysis showed that the responsible locus was localized on chromosome 3q21-25 and flanked by markers D3S2322 and D3S1541 (Figure 2 and Table 2).
Multiple-sequence alignment and DNA sequence chromatograms of BFSP2. A: The multiple-sequence alignment of BFSP2 from primates, rodents, cattle, and zebrafish to humans (Homo sapiens) is shown. The Arg339 residue is located within a highly conserved region. B: DNA sequence chromatograms of the P.R339H mutation in BFSP2 are shown. The G A transversion at position 1091 resulted in the P.R339H mutation.
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Direct cycle sequencing of the amplified fragments of BFSP2 in two affected individuals identified a single base alteration, C.G1091A (Figure 3B), in exon 5 of BFSP2 (GI: 8419), resulting in the substitution of Arg to His at codon 339 (P.R339H). BFSP2 family protein sequences were obtained from NCBI and UCSC websites and multiple-sequence alignments of BFSP2 family proteins from various species were obtained (Figure 3A) using the Vector NTI software.
Denaturing high-performance liquid chromatography results of wild type and mutated BFSP2. DHPLC results show a variant trace for BFSP2 compared to the wild type (WT) trace. The profile in purple is the mutant protein. The profile in blue is the wild type protein.
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DHPLC analysis confirmed this mutation (Figure 4), which cosegregated with all affected individuals in the family.