Sung Yeun Kim

Molecular characterization of D– Korean persons: development of a diagnostic strategy

BACKGROUND: D– frequencies show wide racial differences: in particular, in Korean persons it is approximately 1/100th of that in Caucasians (0.15% vs. 15%). The molecular mechanisms of D– may be unique to races, and thus specific molecular diagnostic approaches are necessary for individual races. Such marked racial differences have been attributed to the founder effect. It was hypothesized that D– frequencies may be affected by genomic variations of Rhesus boxes, which are instruments of unequal crossing‐over.

Phase analysis identifies compound heterozygous deletions of the PARK2 gene in patients with early-onset Parkinson disease.

Kim SY, Seong MW, Jeon BS, Kim SY, Ko HS, Kim JY, Park SS. Phase analysis identifies compound heterozygous deletions of the PARK2 gene in patients with early‐onset Parkinson disease.

VSX1 gene and keratoconus: genetic analysis in Korean patients.

Purpose: The visual system homeobox 1 (VSX1) gene variants have recently been shown to be associated with keratoconus. To replicate this finding, we performed a genetic analysis of the VSX1 gene in a Korean case–control sample. Methods: Patients with keratoconus and healthy control subjects were recruited from Seoul National University Hospital. A diagnosis of keratoconus was made based on clinical examinations and the presence of characteristic topographic features. For all patients and controls, the whole coding region and the exon–intron junctions of the VSX1 gene were analyzed by direct sequencing. Results: Fifty-three patients with keratoconus and 100 healthy volunteers were included. We observed 2 novel missense substitutions (Leu17Val and Val199Leu) and 1 previously reported substitution (Gly160Val) in 6 of the 53 affected probands. Because these substitutions have been identified in unaffected individuals, they were not considered to be pathogenic. No intragenic polymorphism was associated with a significantly increased risk of keratoconus. Conclusions: We cannot confirm the previously reported association of the VSX1 gene variants with keratoconus. Our results suggest that the VSX1 gene and its mutations with amino acid changes do not play a major role in the pathogenesis of keratoconus.

Relative contribution of SCA2, SCA3 and SCA17 in Korean patients with parkinsonism and ataxia

We examined the relative significance of SCA2, SCA3 and SCA17 in Koreans patients with parkinsonism and ataxia. We recruited patients with either parkinsonism (n = 524; PD = 386 and MSA = 138) or ataxia (n = 44) as their main clinical feature for two years. These patients were screened for SCA2, SCA3 and SCA17. Six cases carried SCA2; one, SCA3; and eight, SCA17. In SCA2 patients, one patient exhibited MSA-P phenotype, and the other five exhibited ataxia. The single patient with SCA3 showed ataxia. In SCA17 patients, one patient presented ataxia, the other seven patients showed parkinsonism (three PD and four MSA-P). Dopamine transporter (DAT) imaging was performed in a subset of ataxic or parkinsonian SCA2 or SCA17, all of whom showed decreased DAT binding. In Korean population, the mutation frequencies of SCA2 and SCA17 were similar. SCA2 was a more significant cause of ataxia, whereas SCA17 was a more significant cause of parkinsonism. Contribution of SCA3 to parkinsonism was insignificant.

Investigation of the Association between Normal-tension Glaucoma and Single Nucleotide Polymorphisms in Natriuretic Peptide Gene

Purpose The expression of natriuretic peptides in the neural bundles of the anterior portion of the optic nerves and their functions in regulating vessel tone and blood flow may suggest a possible role in the pathogenesis of glaucoma. The purpose of this study was to investigate the association between normal-tension glaucoma and the genetic variations of atrial natriuretic peptide (Nppa) and natriuretic peptide receptor A (Npr1) gene. Methods Sixty-seven Korean normal-tension glaucoma (NTG) patients and 100 healthy subjects (as normal controls) were enrolled. DNA from peripheral blood leukocytes was extracted, and the genotypes of five polymorphisms (c.94G>A, c.454T>C, IVS1+16C>T, IVS2+701G>A, and c.-764C>G) in the Nppa gene and one polymorphism (c.1023G>C) in the Npr1 gene were determined using the restriction fragment length polymorphism and the SNaPshot methods. The genotype and allele frequencies of these polymorphisms in patients with NTG and normal controls were compared using the Fishers exact test and the chi-square test. Results In both groups, the genotype distributions were in accordance with the Hardy-Weinberg equilibrium. There was no significant difference in the frequency of the Nppa and Npr1 alleles or genotypes in the normal-tension glaucoma group as compared to the control group. Conclusions Nppa and Npr1 gene polymorphisms are not associated with normal-tension glaucoma, suggesting that this gene does not have an important role in the pathogenesis of optic neuropathy in this disease.