Karyotype analysis of 12 841 cases of amniotic fluid cells and risk assessment of missed diagnosis in molecular techniques

Abstract

Objective To evaluate the distribution of fetal abnormal chromosome karyotype in mid-pregnancy and analyse the possible misdiagnosis risks of molecular techniques in clinical prenatal diagnosis. Methods Fetal karyotype (fetal cell collected from amniotic fluid) in Prenatal Diagnosis Center of Zhejiang Province between 2001 and 2010 were retrospectively analyzed on distribution according to 7 different referral indication: positive screening for trisomy 21, trisomy 18, advanced maternal age, abnormal history of pregnancies, abnormal family history, fetal structural abnormalities and others. The combination of trisomy 21, trisomy 18 and trisomy 13 (T21/18/13 Group) and the aneuploidies of chromosome 21, 18, 13, X, Y (21/18/13/X/Y Group) were further analyzed based on the current molecular target detection range. Results There were 462 cases out of 12 481 with chromosomal abnormality (3.60%, 462/12 841), with 215 cases of high risk (detection rate 1.67%, 215/12 841) and 247 cases of low risk (detection rate 1.92%, 247/12 841). Under different indications, the detection rate on abnormal chromosome of high risk (high-risk CA) is different,abnormal fetal ultrasoundis the highest(27.27%, 24/88). Among the high-risk CA, T21/18/13 Group accounted for 72.56%(156/215), while the 21/18/13/X/Y Group accounted for 94.88%(204/215). For the 7 regular indications, the high-risk CA distribute different; Except the T21/18/13 Group and 21/18/13/X/Y Group, the rates of other abnormal chromosome karyotype in the high risk CA were 0.28%(2/719)-12.5%(11/88) and 0.06%(4/6 915)-1.14%(1/88)according to different indication, respectively. Conclusions The distribution of abnormal karyotype were different under different referral indication; the detection power and possible misdiagnosis risks were varied under different indication for each molecular technique. It was suggested that doctors should select suitable molecular technique according to different clinical indications and each molecular method has its own limitations.(Chin J Lab Med, 2015, 38: 517-521) Key words: Chromosome aberrations; Prenatal diagnosis; Karyotyping; Molecular diagnostic techniques