title: Fragile X syndrome screening in Chinese children with unknown intellectual developmental disorder.
abstract: BACKGROUND
  Fragile X syndrome is the most common genetic disorder of intellectual developmental disorder/mental retardation (IDD/MR). The prevalence of FXS in a Chinese IDD children seeking diagnosis/treatment in mainland China is unknown.
  
  
  METHODS
  Patients with unknown moderate to severe IDD were recruited from two children's hospitals. Informed consent was obtained from the children's parents. The size of the CGG repeat was identified using a commercial TP-PCR assay. The influence of AGG interruptions on the CGG expansion during maternal transmission was analyzed in 24 mother-son pairs (10 pairs with 1 AGG and 14 pairs with 2 AGGs).
  
  
  RESULTS
  553 unrelated patients between six months and eighteen years of age were recruited. Specimens from 540 patients (male:female = 5.2:1) produced high-quality TP-PCR data, resulting in the determination of the FMR1 CGG repeat number for each. The most common repeat numbers were 29 and 30, and the most frequent interruption pattern was 2 or 3 AGGs. Five full mutations were identified (1 familial and 4 sporadic IDD patients), and size mosaicism was apparent in 4 of these FXS patients (4/5 = 80%). The overall yield of FXS in the IDD cohort was 0.93% (5/540). Neither the mean size of CGG expansion (0.20 vs. 0.79, p > 0.05) nor the frequency of CGG expansion (2/10 vs. 9/14, p > 0.05) was significantly different between the 1 and 2 AGG groups following maternal transmission.
  
  
  CONCLUSIONS
  The FMR1 TP-PCR assay generates reliable and sensitive results across a large number of patient specimens, and is suitable for clinical genetic diagnosis. Using this assay, the prevalence of FXS was 0.93% in Chinese children with unknown IDD.
authors.affiliation: Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, China. cxlwx@sina.com.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing, China. wang66jm@163.com.
authors.forename: Jingmin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, China. xiehua_2005@126.com.
authors.forename: Hua
authors.initials: H
authors.lastname: Xie
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing, China. hopewillcome@126.com.
authors.forename: Wenjuan
authors.initials: W
authors.lastname: Zhou
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing, China. dryewu@263.net.
authors.forename: Ye
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Neurology, Affiliated Children's Hospital of Capital Institute of Pediatrics, Beijing, China. colalawang@sina.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Beijing Microread Genetech Co., Ltd, Beijing, China. mr_qinjian@126.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Qin
authors.affiliation: Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, China. guoguo0520@sina.com.
authors.forename: Jin
authors.initials: J
authors.lastname: Guo
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing, China. gu325q@sina.com.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Gu
authors.affiliation: Department of Genetics, Jiangxi Previncial Children's Hospital, Jiangxi, China. shellychenchina@sina.cn.
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing, China. jitaoyun@163.com.
authors.forename: Taoyun
authors.initials: T
authors.lastname: Ji
authors.affiliation: Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, China. zangyu0612@sohu.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: State Key Lab of Medical Genetics, Central South University, Changsha, China. zhiminxiong@foxmail.com.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Xiong
authors.affiliation: Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, China. wangliwen2@vip.sina.com.
authors.forename: Liwen
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing, China. wxrwwn@gmail.com.
authors.forename: Xiru
authors.initials: X
authors.lastname: Wu
authors.affiliation: Research & Technology Development, Asuragen, Inc., Austin, TX, USA. glatham@asuragen.com.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Latham
authors.affiliation: Municipal Key Laboratory of Child Development and Nutriomics, Capital Institute of Pediatrics, Beijing, China. jiangyw@263.net.|Department of Pediatrics, Peking University First Hospital, Beijing, China. jiangyw@263.net.
authors.forename: Yuwu
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000453:epidemiology*; D005838:Genotype; D006801:Humans; D007223:Infant; D008607:Intellectual Disability / Q000209:etiology; D008297:Male; D010375:Pedigree; D016133:Polymerase Chain Reaction; D015995:Prevalence
chemical_list: D051860:Fragile X Messenger Ribonucleoprotein 1; C497683:FMR1 protein, human