Prenatal diagnosis of chromosomal abnormalities using QF-PCR and chromosomal microarray analysis at a single centre
Prenatal Genetics
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Primary Categories:
- Prenatal Genetics
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Secondary Categories:
- Prenatal Genetics
Introduction:
Serum screening and level II ultrasonography enables detection of high risk pregnancies at various centers. The confirmation of 5 common aneuploidies can be done by QF-PCR and in addition microdeletion and microduplication syndromes can be detected by chromosomal microarray (CMA). In present report, we describe the aneuploidies detected in last 2 years at a tertiary care centre following invasive testing.
Methods:
High risk of aneuploidies was identified on dual screen, combined screen, quad screen and NIPS in different pregnancies. Informant consent was taken for invasive procedures and genetic testing as per ICMR guidelines and PNDT Act. Medical terminations of pregnancy after 24 weeks were done with recommendations from the Institute Medical Board.
Results:
n the 37 positive cases identified on genetic testing, the gestation ranged from 12 weeks to 28 weeks. The aneuploidies detected included trisomy 21, trisomy 18, trisomy 13, mosaic Turner syndrome, XYY syndrome and Klinefelter syndrome. The soft markers in pregnancies in which trisomy 21 (T21) was detected included absent nasal bone, increased nuchal thickness, echogenic bowel, pyelectasis, prominent cisterna magna, cystic hygroma, ductus venosus-systemic shunt, echogenic focus in left ventricle, and aberrant right subclavian artery (ARSA). The soft markers in pregnancies with final diagnosis of trisomy 18 (T18) included unilateral or bilateral choroid plexus cyst, ventriculomegaly, omphalocele, ARSA and club foot. The only pregnancy with trisomy 13, the serum screening was normal but there was persistent bilateral fetal renal pyelectasis. The microdeletion syndromes detected included chr. 11p11.2 deletion, chr.12p13.33 deletion, 10q11.21q11.22 and chr. 16p13.11 deletion. The duplication syndromes identified included chr. 3q11.2q22.3, chr. 3q26.2q29, 11q13.4q25, chr. 12p13.33p13.31, chr.1p21.1q21.2 duplications. The size of deletion and duplication ranged from 789 kb to 33091 kb.
Conclusion:
QF-PCR and CMA enabled diagnosis of aneuploidies, microdeletion and duplication syndromes in patients with high risk on serum screening and/or having multiple soft markers. Absent nasal bone with additional markers indicate presence of underlying trisomy 21 and persistent bilateral choroid plexus cyst with growth retardation was indicator for trisomy 18. Few of the pregnancies with abnormal serum screening for T21 or T18 ultimately turned out to be microdeletion syndrome or suggestive of both microdeletion and microduplication.
Serum screening and level II ultrasonography enables detection of high risk pregnancies at various centers. The confirmation of 5 common aneuploidies can be done by QF-PCR and in addition microdeletion and microduplication syndromes can be detected by chromosomal microarray (CMA). In present report, we describe the aneuploidies detected in last 2 years at a tertiary care centre following invasive testing.
Methods:
High risk of aneuploidies was identified on dual screen, combined screen, quad screen and NIPS in different pregnancies. Informant consent was taken for invasive procedures and genetic testing as per ICMR guidelines and PNDT Act. Medical terminations of pregnancy after 24 weeks were done with recommendations from the Institute Medical Board.
Results:
n the 37 positive cases identified on genetic testing, the gestation ranged from 12 weeks to 28 weeks. The aneuploidies detected included trisomy 21, trisomy 18, trisomy 13, mosaic Turner syndrome, XYY syndrome and Klinefelter syndrome. The soft markers in pregnancies in which trisomy 21 (T21) was detected included absent nasal bone, increased nuchal thickness, echogenic bowel, pyelectasis, prominent cisterna magna, cystic hygroma, ductus venosus-systemic shunt, echogenic focus in left ventricle, and aberrant right subclavian artery (ARSA). The soft markers in pregnancies with final diagnosis of trisomy 18 (T18) included unilateral or bilateral choroid plexus cyst, ventriculomegaly, omphalocele, ARSA and club foot. The only pregnancy with trisomy 13, the serum screening was normal but there was persistent bilateral fetal renal pyelectasis. The microdeletion syndromes detected included chr. 11p11.2 deletion, chr.12p13.33 deletion, 10q11.21q11.22 and chr. 16p13.11 deletion. The duplication syndromes identified included chr. 3q11.2q22.3, chr. 3q26.2q29, 11q13.4q25, chr. 12p13.33p13.31, chr.1p21.1q21.2 duplications. The size of deletion and duplication ranged from 789 kb to 33091 kb.
Conclusion:
QF-PCR and CMA enabled diagnosis of aneuploidies, microdeletion and duplication syndromes in patients with high risk on serum screening and/or having multiple soft markers. Absent nasal bone with additional markers indicate presence of underlying trisomy 21 and persistent bilateral choroid plexus cyst with growth retardation was indicator for trisomy 18. Few of the pregnancies with abnormal serum screening for T21 or T18 ultimately turned out to be microdeletion syndrome or suggestive of both microdeletion and microduplication.