Objective:To investigate the distribution characteristics of the abnormal karyotpye in Children of Chongqing

to provide the information for management

prenatal diagnosis and intervention. Methods:Samples of the peripheral blood lymphocyte from 4 628 children were prepared with routine cytogenetic methods

G-bangding was employed for karyotype analysis

and C-banding was used when necessary. Results:A total of 22.67%(1 049/4 628) patients were identified to have abnormalities with 73 kinds of karyotypes. Among these aberrations

874(83.32%) cases were euchromosome malformation

159(15.16%)were sex chromosome malformation

and Down’s syndrome

Turner’s syndrome were the most common. Mental retardation

short stature and congenital malformation were the three main causes of genetic counseling

and the major age grades were infants

school children and preschool children in-sequence

42.57%(742/1 743)with mental retardation

9.98%(98/982) with short stature

and 8.10%(56/691)with congenital malformation were detected to have abnormalities

which were coincided with clinical diagnosis

respectively. Conclusion:The abnormal karyotypes are various and complex in Chongqing

routine karyotyping is necessary for children of mental retardation

congenital malformation and growth retardation with unknown reason

since it can benefit for early management and intervention of genetic diseases.