title: Down syndrome and consanguinity.
abstract: BACKGROUND
  Among the genetics disorders, Down syndrome (DS) is the major cause of mental retardation, congenital heart and intestinal disease. So far, no certain therapeutic method has been suggested for the treatment of this syndrome. The aim of the current survey was to investigate the frequency of parental consanguinity, maternal age in the patients with DS.
  
  
  METHODS
  This study was conducted on 38 consecutive patients with clinically and laboratory confirmed DS who referred to the genetic lab of a referral University Hospital. The G-banding method for karyotyping was employed.
  
  
  RESULTS
  The patients were 21 males and 17 females within the age of 16 days to 28 years old. Free trisomy (92.1%, n = 35) was the most common chromosomal abnormality. The frequency of DS was higher among the non-consanguine marriages (71.1%) in comparison with the consanguine marriages (28.9%). Mean age of the mothers in the consanguine marriages (mean = 27.1 ± 6.3) was lower than in the non-consanguine marriages (mean = 31.1 ± 7.7).
  
  
  CONCLUSIONS
  Higher frequency of DS among the non-consanguine marriages in comparison with the consanguine marriages, may suggest that DS diagnostic tests might be done on all embryos regardless of the parents' familial relationship.
authors: Student Research Committee, Faculty of Medicine, Mashhad, Iran.
authors: Amir Akhavan
authors: AA
authors: Rezayat
authors: Medical Genetics, Faculty of Medicine, Mashhad, Iran.
authors: Mohammad Hassanzadeh
authors: MH
authors: Nazarabadi
authors: Student Research Committee, Faculty of Medicine, Mashhad, Iran.
authors: Mohammad Sobhan Sheikh
authors: MS
authors: Andalibi
authors: Student Research Committee, Faculty of Medicine, Mashhad, Iran.
authors: Hossein Mohaddes
authors: HM
authors: Ardabili
authors: Student Research Committee, Faculty of Medicine, Mashhad, Iran.
authors: Maryam
authors: M
authors: Shokri
authors: Medical Genetics, Faculty of Medicine, Mashhad, Iran.
authors: Salmeh
authors: S
authors: Mirzaie
authors: Health Sciences Research Center, Department of Biostatistics and Epidemiology, School of Health, Mashhad University of Medical Sciences, Razavi Khorasan, Iran.
authors: Lida
authors: L
authors: Jarahi
keywords: Consanguinity; Down syndrome; chromosomal disorder