Genetic analysis of a family with 9q34.3 microdeletion and microduplication caused by abnormal chromosome balance structure

OBJECTIVE To perform prenatal diagnosis, pedigree analysis, and genetic counseling of a pregnant woman who gave birth to a child with Kleefstra syndrome. METHODS Karyotype analysis, chromosomal microarray analysis (CMA), multiplex ligation-dependent probe amplification (MLPA) and fluorescence in situ hybridization (FISH) were used of peripheral blood and amniotic fluid to find causes. Recurrence risk assessment was performed later. RESULTS The amniotic fluid sample showed a 9q34.3 microduplication of arr (hg19) 9q34.3 (140 168 806-141 020 389)× 3, which overlapped the 9q34.3 microdeletion region of proband. The pregnant woman was detected with a balanced translocation of ish, t(9;17)(9q34.3; qter) (9p+; 17p+,9q+, 17q+). No other abnormal results were found in the family. CONCLUSION Offspring who share the same chromosome segment deletion or duplication are always from parent who carries balanced chromosomal structural aberration.