title: Analysis of cosegregation of intragenic DNA sequence variations as markers of maternal cell contamination in prenatal diagnosis of β-thalassemia.
abstract: Prenatal diagnosis of 3 HBB gene mutations causing β-thalassemia and hemoglobin D Punjab segregated in a South Indian nuclear family is reported along with a method identified as control for maternal cell contamination (MCC). Amplicons of the HBB gene from genomic DNA obtained from the blood of a thalassemic first child (proband), both parents, and a chorionic villus sample of their second pregnancy were directly sequenced. A test for MCC was performed by genotyping polymorphic microsatellite markers (D21S11 and D21S1270) by quantitative fluorescence polymerase chain reaction (QF-PCR) and capillary gel electrophoresis. The pedigree analysis showed proband as a compound heterozygote of NG_000007.3:g.70691G>C and NG_000007.3:g.72128T>C mutations; showed the father as a compound heterozygote of NG_000007.3:g.72128T>C and NG_000007.3:g.71938G>C mutations; and showed the mother as a heterozygous carrier of the NG_000007.3:g.70691G>C mutation. The fetus inherited a normal maternal allele and a mutant paternal allele NG_000007.3:g.72128T>C and was ascertained a carrier of β-thalassemia. Analysis of cosegregation of 5 other single nucleotide polymorphisms (SNPs) in the family, including NG_000007.3:g.70603T>C, NG_000007.3:g.71055G>C, NG_000007.3:g.71113T>G, NG_000007.3:g.72332G>A, and NG_000007.3:g.72334A>C, defined the disease allele haplotypes. QF-PCR showed no extra maternal alleles in the fetal sample. Prenatal diagnosis of mutations and an absence of MCC was confirmed by cosegregation of the SNPs, suggesting the utility of a panel of such polymorphisms that can serve to identify MCC quickly and reliably.
authors.affiliation: Division of Biotechnology, Manipal Life Sciences Center, Manipal University, Manipal-576104, India.
authors.forename: Abdul V
authors.initials: AV
authors.lastname: Saadi
authors.forename: Katta M
authors.initials: KM
authors.lastname: Girisha
authors.forename: Puthiya M
authors.initials: PM
authors.lastname: Gopinath
authors.forename: Kapaettu
authors.initials: K
authors.lastname: Satyamoorthy
mesh_terms: D000328:Adult; D001483:Base Sequence; D002675:Child, Preschool; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification*; D004252:DNA Mutational Analysis; D017931:DNA Primers / Q000235:genetics; D005260:Female; D006580:Genetic Carrier Screening; D006239:Haplotypes; D006455:Hemoglobins, Abnormal / Q000235:genetics; D006801:Humans; D008297:Male; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011296:Prenatal Diagnosis; D055815:Young Adult; D017086:beta-Thalassemia / Q000175:diagnosis* / Q000235:genetics*
chemical_list: D017931:DNA Primers; D006455:Hemoglobins, Abnormal; D004247:DNA