Incidence of Fragile X Syndrome in Korean Patients with Mental Retardation.

Choi, Young Min; Hwang, Do Yeong; Jun, Jong Kwan; Choe, Jin; Park, Sung Hyo; Noh, Mee Kyung; Oh, Sun Kyung; Ku, Seung Yup; Suh, Chang Suk; Kim, Seok Hyun; Yang, Se Won; Cho, Soo Cheol; Moon, Shin Yong; Lee, Jin Yong

Original Article

Korean Journal of Obstetrics & Gynecology 1999;42(11):2458-2464.
Published online January 1, 2001.

Incidence of Fragile X Syndrome in Korean Patients with Mental Retardation.

Young Min Choi, Do Yeong Hwang, Jong Kwan Jun, Jin Choe, Sung Hyo Park, Mee Kyung Noh, Sun Kyung Oh, Seung Yup Ku, Chang Suk Suh, Seok Hyun Kim, Se Won Yang, Soo Cheol Cho, Shin Yong Moon, Jin Yong Lee

Abstract

Fragile X syndrome is the most common cause of inherited mental retardation. It accounts for 0.2% - 2.7% of patients with mental retardation, based upon the molecular genetic diagnosis. However, the exact prevalence of fragile X syndrome in Korean patients with mental retardation is unknown. We have performed cytogenetic and molecular analysis for fragile X syndrome in 212 Korean patients with mental retardation. Among them, six patients (2.8%) was identified as carrying fragile X syndrome by both cytogenetic and molecular analysis. The results by cytogenetic analysis was identical to those by molecular analysis. Cytogenetic analysis of 6 carriers (mothers of patients with proven fragile X syndrome) showed a fragile X chromosome in one patients (16.7%) while molecular analysis revealed premutation in all patients. PCR method using Klentaq1 Pfu polymerase showed the same results as those by PCR method using Exo(-) Pfu polymerase, but the former method is recommended because of its simplicity in technical aspect. These data suggest that the prevalence of fragile X syndrome in Korean patients with mental retardation is 2.8%, not significantly different from those in Caucasians.

Key Words: Fragile X syndrome, Mental Retardation, Southern blot analysis, PCR, Chromosome analysis, Southern