Objective: To evaluate the diagnostic feasibility of mutation analysis and prenatal genetic diagnosis genetic analysis of IL2RG gene in two families with a birth history of X-linked severe combined immunodeficiency (X-SCID).
Methods: Blood samples of a male infant patient of X-SCID and his mother in family 1 and the parents of another deceased child with X-SCID in family 2 from January 2012 to February 2013 were collected.Eight exons comprising IL2RG open reading frame and their exon/intron boundaries were analyzed by bi-directional direct sequencing of polymerase chain reaction (PCR) products. Prenatal genetic diagnoses were performed by chorionic villus sampling after the genotypes of maternal probands were identified in family 1.
Results: Two mutations of IL2RG gene were identified in these two families. The c.361-363delGAG (p.E121del) mutation was identified in family 1. The c.510-511insGAACT (p.W173X) mutation appeared in family 2. The two mutations of c.361-363delGAG (p.E121del) and c.510-511insGAACT (p.W173X) were novel. The two novel mutations were absent in 100 normal controls. The pregnancy in family 1 continued and the infant showed no symptom of X-SCID at 1 year after birth. The aunt (II-3) of proband in family 1 was not a carrier. The female fetus in family 1 had no mutation.
Conclusions: Two novel mutations of c.361-363delGAG (p.E121del) and c.510-511insGAACT (p.W173X) in IL2RG gene may be a major cause of disease in two families with X-SCID. And direct sequencing of IL2RG gene provides genetic counseling, prenatal diagnosis and carrier screening for families with X-SCID.