[Mutation analyses and prenatal diagnosis in two families of X linked severe combined immunodeficiency caused by IL2RG gene novel mutation].

[severe combined immunodeficiency]

To evaluate the diagnostic feasibility of mutation analysis and prenatal genetic diagnosis genetic analysis of IL 2 RG gene in two families with a birth history of X-linked severe combined immunodeficiency (X-SCID ).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 IL 2 RG 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 .Two mutations of IL 2 RG gene were identified in these two families . The c .361 -363 delGAG (p .E 121 del ) mutation was identified in family 1 . The c .510 -511 insGAACT (p .W 173 X ) mutation appeared in family 2 . The two mutations of c .361 -363 delGAG (p .E 121 del ) and c .510 -511 insGAACT (p .W 173 X ) 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 .Two novel mutations of c .361 -363 delGAG (p .E 121 del ) and c .510 -511 insGAACT (p .W 173 X ) in IL 2 RG gene may be a major cause of disease in two families with X-SCID . And direct sequencing of IL 2 RG gene provides genetic counseling , prenatal diagnosis and carrier screening for families with X-SCID .