Journal of the korean academy of Pediatric Dentistry (대한소아치과학회지)

Korean Academy of Pediatric Dentistry (대한소아치과학회)
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A Novel PAX9 Mutation in a Family with Non-Syndromic Oligodontia

비증후군성 부분 무치증 환자에서 PAX9 유전자 돌연변이

  • Lee, Ye ji (Department of Pediatric Dentistry, School of Dentistry, Seoul National University) ;
  • Shin, Teo Jeon (Department of Pediatric Dentistry, School of Dentistry, Seoul National University) ;
  • Hyun, Hong-Keun (Department of Pediatric Dentistry, School of Dentistry, Seoul National University) ;
  • Kim, Jung-Wook (Department of Pediatric Dentistry, School of Dentistry, Seoul National University) ;
  • Lee, Sang-Hoon (Department of Pediatric Dentistry, School of Dentistry, Seoul National University) ;
  • Kim, Young-Jae (Department of Pediatric Dentistry, School of Dentistry, Seoul National University)
  • 이예지 (서울대학교 치의학대학원 소아치과학교실) ;
  • 신터전 (서울대학교 치의학대학원 소아치과학교실) ;
  • 현홍근 (서울대학교 치의학대학원 소아치과학교실) ;
  • 김정욱 (서울대학교 치의학대학원 소아치과학교실) ;
  • 이상훈 (서울대학교 치의학대학원 소아치과학교실) ;
  • 김영재 (서울대학교 치의학대학원 소아치과학교실)
  • Received : 2016.01.08
  • Accepted : 2016.03.08
  • Published : 2016.08.31
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Abstract

The aim of this study was to identify the causative genetic mutation in a family with non-syndromic oligodontia. The 7-year-old female proband and her mother underwent oral examination, panoramic radiographs were obtained and blood samples were collected. All exons of the PAX9 gene were amplified by polymerase chain reaction and sequenced. The sequencing results were compared with the standard human gene sequence. The proband lacked 11 permanent teeth, and her mother lacked 19 permanent teeth. No other birth defects were observed. As a result of gene analysis, there was a novel heterozygous nonsense mutation (c.184G>T, $p.Glu62^*$) in exon 2 in both affected subjects. It is suspected that the nonsense mutation leads premature termination of translation, yields a truncated protein 280 amino acids shorter than the wild-type protein. These defects include parts of the paired box domain, a DNA-binding site that plays an essential role in protein function. Otherwise, more likely the mutant transcript would be degraded by nonsense-mediated decay system, resulting haploinsufficiency to cause oligodontia in this family.

본 연구는 서울대학교 치과병원 소아치과에 내원한 부분 무치증 환자를 대상으로 질환의 원인이 될 수 있는 돌연변이를 규명하고, 그 역할에 대하여 고찰하고자 하였다. 다수의 영구치 결손을 주소로 서울대학교 치과 병원에 내원 한 7세 여아와 어머니를 대상으로 구강검진 및 파노라마 방사선 촬영을 진행하였다. 연구 동의서를 받고, 유전자 검사를 위한 채혈을 시행하였다. PAX9 유전자의 모든 exon에 대해 특이적인 primer를 이용하여 중합효소 연쇄반응을 시행하였으며, 해당 산물을 정제하고 염기서열분석을 진행하였다. 결과는 NCBI Gene Bank와 대조하여 해당 영역의 돌연변이를 조사하였다. 7세 환아는 총 11개의 영구치 결손이 관찰되었으며, 어머니는 총 19개의 영구치 결손이 관찰되었다. 치아 결손 외에 손톱, 모발, 피부, 땀샘과 연관 된 다른 결함은 관찰되지 않았다. 유전자 분석 결과, PAX9의 exon 2 영역에서 nonsense mutation(c.184G>T, $p.Glu62^*$)을 확인하였으며, 대상자 모두에서 이형접합 돌연변이로 관찰되었다. 해당 돌연변이의 결과로 exon 2 내에서 전사 종결이 일어나게 되며, 발현 된 단백질은 정상 단백질에 비하여 280개의 아미노산이 짧은 상태로 발현된다고 추측할 수 있다. 결손된 부분은 paired box domain 및 DNA binding site 등 해당 단백질의 기능에 있어서 필수적인 영역을 포함하고 있으므로, 부분 무치증을 유발했을 가능성이 높다. 또는 해당 돌연변이의 전사체가 nonsense-mediated decay system(NMD system)에 의하여 분해됨으로써 haploinsufficiency를 유발하여 부분 무치증의 원인으로 작용했을 것으로 사료된다.

Keywords

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