Pathogenesis and prenatal diagnosis of hereditary Glanzmann thrombasthenia / 临床儿科杂志

ABSTRACT

Objective To explore the gene sequencing and prenatal diagnosis of Glanzmann thrombasthenia (GT). Methods The blood samples were drawn from one case of phenotype GT pediatric patient, patient’s parents, and one normal control. The amniotic lfuid and cord blood from the fetus of patient’s mother were collected. When the fetus was born 2 days, the blood was drawn. The coagulation routine test and platelet aggregation test were performed. The expression of platelet membrane glycoprotein (GP) IIb and GPIIIa were tested by lfow cytometry. Microsatellite technology is used to determine whether fetal cord blood is contaminated with maternal cells. The expressed region and the junctional zone between exon and introns of GPIIb and GPIIIa were ampliifed by PCR technology from blood sample of patient, patient’s parents, and fetus’s cord and 2 days after birth. The PCR products were then subjected to DNA sequencing. Results Adenosine diphosphate (ADP) cannot induce the platelet aggregation in the patient. The max rate of the platelet aggregation in the fetus’s cord blood was half of the normal. However, the max aggregation rate induced by ADP in the blood sample of parents and fetus 2 days after birth were equal to normal. The mean lfuorescence intensity (MnX) of platelet membrane GPIIb and GPIIIa in the patient were 10%and nearly zero of the normal control, respectively, while those in the parents, the fetus’s cord blood and 2 days after birth were more than 90%and 30%to 50%of the normal control. The cast-off cells in amniotic lfuid and the DNA in cord blood analysis by microsatellite technology conifrmed that the amniotic lfuid and cord blood not contaminated by maternal cells. Gene analysis showed the heterozygosis mutation in exon6 A3829→C and exon9 G42186→A of the patient’s GPIIIa led to the amino acid heterozygosis mutation in GPIIIaHis281→Tyr and Cys400→Pro. These two mutations came from the father and the mother separately. However, there was only one heterozygosis mutation in exon9 G42186→A in the cast-off cells in amniotic lfuid, the fetus’s cord and blood 2 days after birth. Conclusion This GT patient have double heterozygosis mutation. The fetus has heterozygosis mutation conifrmed after birth.