Hypermethylation of IGSF4 gene for noninvasive prenatal diagnosis of thalassemia.
BACKGROUND
For patients with pregnancy-induced thalassemia, fetal cord blood or amniotic fluid is invasively collected in the traditional diagnosis and prediction of thalassemia. However, there is no specific molecular target in the diagnosis of thalassemia using fetal DNA from the plasma of pregnant women.


METHODS
The promoter of cell surface adhesion molecule (IGSF4) gene was found to be down-regulated in patients with homozygous thalassemia, and the expression of IGSF4 was closely associated with the methylation of its promoter. In the present study, mass spectrometric sequencing of methylation was performed using MassARRAY to detect the 12 CpG sites in the promoter of IGSF4 gene.


RESULTS
The methylation degree of these 12 CpG sites was significantly higher than that in healthy subjects (P<0.05). Hierarchical clustering was done in 23 patients with thalassemia and 5 healthy individuals. Results revealed the promoter of IGSF4 gene was highly methylated in thalassemia patients, which was dramatically different from that in healthy subjects (P<0.05). Methylation-specific PCR (MSP) was employed to confirm the methylation of the promoter of IGSF4 gene and results were consistence with those obtained in sequencing with MassARRAY. Real-time PCR showed, when compared with heterozygous subjects, the expression of IGSF4 was significantly down-regulated in thalassemia patients (ratio=0.18).


CONCLUSIONS
The expression of IGSF4 was closely related to the methylation of its promoter, suggesting the methylation of IGSF4 gene is tissue-specific for thalassemia. These findings provide evidence for the non-invasive prenatal diagnosis of thalassemia in terms of epigenetics.
Department of Gynecology and Obstetrics, Southwest Hospital, 3rd Military Medical University, Chongqing, China.
Tian
T
Gao
Yanli
Y
Nie
Hua
H
Hu
Zhiqing
Z
Liang
D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules / Q000235:genetics*; D016000:Cluster Analysis; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D005260:Female; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics*; D013058:Mass Spectrometry; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*; D011401:Promoter Regions, Genetic / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA / Q000379:methods; D013447:Sulfites; D013789:Thalassemia / Q000175:diagnosis*
C403514:CADM1 protein, human; D000075982:Cell Adhesion Molecule-1; D015815:Cell Adhesion Molecules; D017931:DNA Primers; D007136:Immunoglobulins; D013447:Sulfites; C042345:hydrogen sulfite