Mutation analysis and prenatal diagnosis of a Chinese family with X-linked severe combined immunodeficiency

Abstract

To analyze the mutation of IL2RG gene in a Chinese family with a birth history of a dead child suspected of X-linked severe combined immunodeficiency (X-SCID), and to perform prenatal diagnosis with DNA sequencing. Blood samples of the parents of the dead child and chorionic villi at gestational age 11 weeks were collected. Eight exons comprising the open reading frame as well as their exon/intron boundaries of IL2RG gene were analyzed by PCR and bi-directional sequencing. A heterozygous nucleotide substitution c.690C > T (R226C) in exon 5 was detected in the mother, but not in the father. In the second pregnancy of the mother, the mutation of R226C was not detected in the male fetus by prenatal diagnosis, and the heterozygous mutation was detected in the female fetus of the third pregnancy. The reliability of the prenatal genetic diagnosis was confirmed by the one-year follow-up after the neonates were born. The mutation of c.690C>T in IL2RG gene may be the pathologic cause of the proband with X-SCID. DNA sequencing combining sex determination is a valid strategy for prenatal diagnosis of X-SCID.