The Application Of Gene Chip In Molecular Cytogenetic Diagnosis Of INfants With Congenital Defect

Objective To scan and analyse the whole genome of infants with congenital defect that could not be diagnosed by conventional cytogenetic technique, explore the underlying genetic causes of congenital malformation, and investigate the feasibility of array-based comparative genomic hybridization (array-CGH) in molecular cytogenetic diagnosis.Methods Three cases that could not be diagnosed by conventional cytogenetic technique were selected to undergo array-CGH analysis for more precise determination of the size and location of the copy number variations.Results By using array-CGH technique,all the three cases were diagnosed precisely. To case 1, G-banding result indicated the karyotype of the infant was 46,XX,t(7; 9)(q12;q21),while one pathologic submicroscopic CNV [del(22) (q11.2) (17 370 128-19 790 009,-2.42 Mb)] was identified and mapped by array-CGH. To case 2, G-banding result indicated the karyotype of the child was 46,XX,del(1)(q25-q31), while one pathologic CNV [del(1)(q25.1-q31.3)(172 832 580-193 394 460, ~20.561Mb)] was identified and mapped in the genome of the child by array-CGH. To case 3, G-banding result indicated the karyotype of the child was 46,XX,-13,inv9(p13-q13),der(13), while array-CGH analysis indicated the derivative chromosome fragment is origin from 9p with a breakpoint around 9p13.1-p24.3. Conclusion By using array-CGH technique , the cases that could not be diagnosed by conventional cytogenetic technique can be diagnosed precisely. Due to the high-resolution and high-accuracy, array-CGH is considered to be a powerful tool for detection of genomic imbalance and genetic counseling.