Yonsei University

About: Yonsei University is a education organization based out in Seoul, South Korea. It is known for research contribution in the topics: Population & Cancer. The organization has 50162 authors who have published 106172 publications receiving 2279044 citations. The organization is also known as: Yonsei.

Origins and frequencies of SLC26A4 (PDS) mutations in east and south Asians: global implications for the epidemiology of deafness

Abstract: Recessive mutations of SLC26A4 (PDS) are a common cause of Pendred syndrome and non-syndromic deafness in western populations. Although south and east Asia contain nearly one half of the global population, the origins and frequencies of SLC26A4 mutations in these regions are unknown. We PCR amplified and sequenced seven exons of SLC26A4 to detect selected mutations in 274 deaf probands from Korea, China, and Mongolia. A total of nine different mutations of SLC26A4 were detected among 15 (5.5%) of the 274 probands. Five mutations were novel and the other four had seldom, if ever, been identified outside east Asia. To identify mutations in south Asians, 212 Pakistani and 106 Indian families with three or more affected offspring of consanguineous matings were analysed for cosegregation of recessive deafness with short tandem repeat markers linked to SLC26A4. All 21 SLC26A4 exons were PCR amplified and sequenced in families segregating SLC26A4 linked deafness. Eleven mutant alleles of SLC26A4 were identified among 17 (5.4%) of the 318 families, and all 11 alleles were novel. SLC26A4 linked haplotypes on chromosomes with recurrent mutations were consistent with founder effects. Our observation of a diverse allelic series unique to each ethnic group indicates that mutational events at SLC26A4 are common and account for approximately 5% of recessive deafness in south Asians and other populations.

Diffusion-Tensor MR Imaging and Fiber Tractography: A New Method of Describing Aberrant Fiber Connections in Developmental CNS Anomalies

Abstract: Congenital anomalies of the central nervous system (CNS) often demonstrate aberrant white matter connections, which may be better characterized with diffusion-tensor imaging (DTI) and fiber tractography (FT) than with conventional magnetic resonance (MR) imaging. DTI-FT demonstrates abnormal hemispheric fiber connections in callosal agenesis or acquired disease of the corpus callosum. Decreased anisotropy of white matter adjacent to the malformed cortex and an aberrant course of major fiber pathways due to dysplastic white matter are common findings in cortical dysplasia. Increased anisotropy of dysplastic gray matter in heterotopia supports the hypothesis that developing neurons migrate from the ependyma to the cortex with a radial growth pattern. In periventricular leukomalacia, DTI-FT demonstrates an intact corticospinal tract and decreased thalamocortical sensory connections, which are responsible for the spasticity of cerebral palsy owing to impairment of inhibitory function. Joubert syndrome comprises malformation of the cerebellar vermis and an aberrant connection between the cerebellum and the cerebral cortex via an elongated and abnormally shaped superior cerebellar peduncle, which are well visualized with DTI-FT. In developmental CNS disease, DTI-FT demonstrates additional findings beyond those seen with conventional MR imaging. Future studies will focus on determining the significance of the aberrant fiber connections and their relationships to the clinical manifestations of CNS anomalies.