Analysis of prenatal diagnosis results of 206 thalassemia families / 中华围产医学杂志

ABSTRACT

Objective To summarize the geographical distribution,phenotype and genotype data of 206 thalassemia families underwent prenatal diagnosis to provide information for clinical genetic counseling and avoid the birth of severe thalassemia children.MethodsTotally,206 thalassemia families were collected from Southern Medical University Nanfang Hospital from January 2008 to December 2009.Genomic DNA was extracted from peripheral blood,villus,amniotic fluid or cord blood from the couples or the fetuses.Gap-polymerase chain reaction (gap-PCR) and reverse dot blot (RDB) technology were used to detect the common α and β-thalassemia mutations.DNA sequencing was used to detect the rare mutations.Follow-up visit were done half a year after the fetuses were born. Results The 206 thalassemia families came from 12 provinces and areas across China,including Heilongjiang province.Mutations detected in α-thalassemia families included --SEA/,-α3.7/,-α4.2/,αCS α/ and αQS α/,which were all included in the testing kit. While there were 4 kinds of β-thalassemia mutations,Gγ+ (A γδβ)0,-28(A→C),CD54-58(-TATGGGCAACCCT) and CD37(G→A),could not be identified with routine testing kit. The 57 α-thalassemia families consisted of 11(19.3％) severe thalassemia,induding 8 Bart's hydrops syndrome and 3 Hb H disease,26(45.6％) heterozygote and 20(35.1％) normal infants,and the 149 β-thalassemia majors families consisted of 28 (18.8％) severe thalassemia,82(55.0％) heterozygote and 39 (26.2％) normal infants.Among the β-thalassemia heterozygotes,there was one 13-trisomy.Follow-up visit found that babies with Bart ' s hydrops syndrome (n =8),Hb H disease (n =3),β-thalassemia majors (n =28) and β thalassemia heterozygote combined with 13-trisomy(n=1) were aborted.Conclusions Thalassemia was found in some north area other than south of China,which should be paid more attention by clinicians.Gap-PCR and PCR-RDB technology are effective measures for thalassemia prenatal diagnosis in identifying major thalassemia fetuses before their birth,thus reduce the birth rate of thalassemia baby.But missed diagnosis might exist during the screening,so it is necessary to perform DNA sequencing on those patients with positive symptoms and negative common genetic diagnostic results.At the same time,prenatal diagnosis of chromosomal disorders should not be neglected for high-risk families.