مطالعه سيتوژنتيك 166 بيمار مبتلا به سندرم داون

CYTOGENETIC FINDINGS AMONG 166 DOWNʹS PATIENT

Background & Aims: Trisomy 21 or Downʹs syndrome is the most common cause of mental retardation in children that is compatible with life. It occurs approximately in 11700 live births. The incidence rate of this syndrome increases with increased maternal age as is the case in other chromosomal abnormalities. Although Downʹs syndrome is diagnosed clinically, cytogenetic study is necessary to determine the recurrence risk in the offsprings and relatives. Materials & Methods: According to the family history and physical examination on 1000 mental retarded patients in rehabilation centers of the province, 166 patients were selected as Downʹs syndrome and GTG banding karyotype was carried out on them. Results: 94.58% of karyotypes revealed full trisomy and 5.42% had translocation of chromosome 21 on the other chromosomes. Eight translocations were inherited from mothers and in 1 case it had paternal origin. There was translocation of chromosome 13 on chromosome 14 as well as translocation of chromosome 14 on chromosome 21 in 1 case. One of the cases had 21121 translocation. Discussion: The marital age increased in countries such as Iran for several social reasons and many women become pregnant over 35 years old. This is an alarm for an increasing rate of birth of affected children. Considering the sonographic and serologic findings of Downʹs syndrome as well as findings of this study, it was necessary to establish the prenatal screening centers throughout the country.