Application of GPIIIa gene Taq I polymorphism to determination of carrier status in Glanzmann's thrombasthenia families of Chinese origin.

Glanzmann's thrombasthenia is a bleeding disorder caused by qualitative and/or quantitative defects of platelet membrane glycoprotein (GP) IIb/IIIa complex. The disease is inherited in an autosomal recessive manner. In this paper, cDNA probes were used to study restriction fragment length polymorphisms (RFLPs) in GPIIIa gene. A Taq I polymorphism was identified and this RFLP was composed of variant bands of 6.5 Kb/4.0 and 2.5 Kb with a frequency of 0.46/0.54 in Chinese population. The Taq I polymorphism was further localized by polymerase chain reaction (PCR) method to exon VIII of the GPIIIa gene. In two Glanzmann's thrombasthenia families, the Taq I RFLP studied by both Southern blotting and PCR methods identified the defective GPIIIa gene inherited by patients, and determined the genotype of asymptomatic subjects. Analysis of this Taq I polymorphism by PCR method should be potentially useful in future for the carrier detection and prenatal diagnosis in Glanzmann's thrombasthenia families.