title: "Familial" versus "Sporadic" intellectual disability: contribution of common microdeletion and microduplication syndromes.
abstract: BACKGROUND
  Interstitial Microdeletion and Microduplication syndromes have been proposed as a significant cause of sporadic intellectual disability (ID) but the role of such aberrations in familial ID has not yet been investigated. As the balanced chromosomal abnormalities commonly lead to the recurrent ID or multiple congenital anomalies, this study was designed to evaluate whether it was justified to investigate such aberrations in familial ID patients. Three hundred and twenty eight patients from 101 unrelated Iranian families with more than two ID patients in the first-degree relatives, have been investigated. Assessment of a panel of 21 common Microdeletion and Microduplication syndromes (CMMS) was carried out using Multiplex Ligation-Dependent Probe Amplification (MLPA) technique.
  
  
  RESULTS
  Among the families studied, 27.7% had 4-12, 35.6% had 3 and 36.6% had 2 affected individuals in the first-degree relatives. An autosomal dominant inheritance of Williams-Beuren syndrome (WBS) was detected in a family with no clinical suspicion of WBS. The prevalence of CMMS was therefore,0.99%.
  
  
  CONCLUSIONS
  This is the first investigation of a panel of CMMS in a large sample set of "familial ID patients". The findings of this study showed the low prevalence of CMMSs in "familial ID" patients in spite of the significant contribution of such aberrations in "sporadic ID" which has a very useful practical impact by avoiding unnecessary diagnostic tests in "familial ID" patients.
authors.affiliation: Department of Medical Genetics, Tehran University of Medical Sciences, Tehran, Iran.|Comprehensive Genetic Center, Hope Generation Foundation, Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Rafati
authors.affiliation: Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Elaheh
authors.initials: E
authors.lastname: Seyyedaboutorabi
authors.affiliation: Tehran Welfare Organization, Tehran, Iran.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Ghadirzadeh
authors.affiliation: Tehran Welfare Organization, Tehran, Iran.
authors.forename: Yaser
authors.initials: Y
authors.lastname: Heshmati
authors.affiliation: Tehran Welfare Organization, Tehran, Iran.
authors.forename: Homeira
authors.initials: H
authors.lastname: Adibi
authors.affiliation: Division of Pediatric Neurology, Department of Pediatrics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Zarrintaj
authors.initials: Z
authors.lastname: Keihanidoust
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Eshraghian
authors.affiliation: Department of Genetics, Science and Research Branch, Islamic Azad University, Tehran, Iran.
authors.forename: Gholam Reza
authors.initials: GR
authors.lastname: Javadi
authors.affiliation: Gene Clinic, Tehran, Iran.
authors.forename: Jila
authors.initials: J
authors.lastname: Dastan
authors.affiliation: Department of Public Health and Social Medicine, Shahid Beheshti University of Medical Sciences, Evin, Tehran, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Mosavi-Jarrahi
authors.affiliation: Comprehensive Genetic Center, Hope Generation Foundation, Tehran, Iran.
authors.forename: Azadeh
authors.initials: A
authors.lastname: Hoseini
authors.affiliation: Gene Clinic, Tehran, Iran.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Purhoseini
authors.affiliation: Department of Medical Genetics, Tehran University of Medical Sciences, Tehran, Iran.|Comprehensive Genetic Center, Hope Generation Foundation, Tehran, Iran.|Gene Clinic, Tehran, Iran.
authors.forename: Saeed R
authors.initials: SR
authors.lastname: Ghaffari