Background:
Beta thalassemia is a common disorder with autosomal
recessive inheritance. The most prenatal diagnostic methods are the invasive
techniques that have the risk of miscarriage. Now the non-invasive methods will be
gradually alternative for these invasive techniques.
Objective:
The aim of this study is to evaluate and compare the diagnostic value of two
non-invasive diagnostic methods for fetal thalassemia using cell free fetal DNA (cff-DNA)
and nucleated RBC (NRBC) in one sampling community.
Methods:
10 ml of blood was taken in two k3EDTA tube from 32 pregnant women
(mean of gestational age = 11 weeks), who themselves and their husbands had minor
thalassemia. One tube was used to enrich NRBC and other was used for cff-DNA
extraction. NRBCs were isolated by MACS method and immunohistochemistry; the
genome of stained cells was amplified by multiple displacement amplification (MDA)
procedure. These products were used as template in b-globin segments PCR. cff-DNA
was extracted by THP method and 300 bp areas were recovered from the agarose gel
as fetus DNA. These DNA were used as template in touch down PCR to amplify b-globin
gen. The amplified b-globin segments were sequenced and the results compared with
CVS resul.
Results:
The data showed that sensitivity and specificity of thalassemia diagnosis by
NRBC were 100% and 92% respectively and sensitivity and specificity of thalassemia
diagnosis by cff-DNA were 100% and 84% respectively.
Conclusion:
These methods with high sensitivity can be used as screening test but due
to their lower specificity than CVS, they cannot be used as diagnostic test.
Fetomaternal microchimerism and genetic diagnosis: On the origins of fetal cells and cell-free fetal DNA in the pregnant woman
