A Cytogenetic Survey of 8584 Children Referred for

Abstract Objectives: We evaluated the type and incidence of different chromosomal abnormalities among paediatric patients presented with congenital abnormalities in a paediatric hospital over the past 15 years. Material and methods: Peripheral blood lymphocytes were obtained from 8584 paediatric patients with suspected chromosomal aberrations in the Children's Hospital of Zhejiang University School from 1996 to 2010. Their age were between 0 and 18 years. Cytogenetic analysis was performed by G-banding technique. The cases were grouped according to the reasons of referral for cytogenetic analysis. The frequency of various abnormal karyotypes was analysed. Results: The main indications for cytogenetic analysis were congenital genitourinary defect, which accounted for 39.6% (3402/8584). The referrals of congenital genitourinary defects group increased while other groups decreased during 2006-2010 compared to 1996-2000. Abnormal karyotypes were found in 24.4% (2094/8584) and 77.0% (1612/2094) had autosomal abnormalities. Among them, trisomy 21 was the most frequent one. The remaining 23.0% (482/2094) were sex chromosome abnormalities, 199 cases were structural abnormalities and 283 cases were numerical abnormalities. The ratio of autosomal abnormalities to sex chromosome abnormalities showed a decrease trend. Turner syndrome accounted for 12.7% (265/2094) of abnormal karyotypes. Eighty nine cases of XY female (46,XY complete gonadal dysgenesis) and 58 cases of XX male (46,XX testicular disorder of sexual development) were diagnosed, which consisted of 7.0% (147/2094) in all chromosomal anomalies. Conclusions: The incidence and distribution of cytogenetic abnormalities by karyotype were reviewed. The high rate of chromosomal abnormalities (24.4%) found in our referred population demonstrates the importance of cytogenetic evaluation in patients who are clinically abnormal. The main clinical indications for genetic analysis were congenital genitourinary defects, the ratio between sex chromosome abnormality and autosomal abnormality elevated with the increase of cases referral for congenital genitourinary defects. This is due to referral bias of a paediatric medical center with developed paediatric urology subspecialty. Our data may help in providing some correlation data for genetic counselling on this aspect