.0002IMMUNODEFICIENCY 13 (1 family)
UNC119, GLY22VAL [dbSNP:rs199714731] ClinVar
In a 32-year-old woman with CD4 lymphopenia (IMD13; 615518), Gorska and Alam (2012) identified heterozygosity for a 136G-T transition (base numbering according to NCBI Reference Sequenced NM_005148.3) in exon 1 of the UNC119 gene, resulting in a gly22-to-val (G22V) substitution near the PXXP motif, which is responsible for LCK (153390) activation. The mutation was not found in 60 controls or in the dbSNP Build 132 or HapMap databases. Immunostaining of patient CD4 T cells and G22V-transfected CD4 T cells from a healthy donor showed accumulation of LCK in the RAB11 (see 605570)-positive endosomal compartment; the amount of LCK at the plasma membrane was reduced 2.7- and 2.8-fold in patient and mutant-transfected CD4 T cells, respectively, compared to controls. Proliferation of patient lymphocytes in response to activation with mitogen or antigen was profoundly reduced, with a 20-fold reduction on average compared to minimal normal values; proliferation of mutant-transfected CD4 T cells was also inhibited, with a 2.8- and 2.4-fold reduction in response to mitogen and antigen, respectively, compared to controls. Analysis of CD4 and CD8 T-cell subset proliferation after T-cell receptor (see TCR, 186880) stimulation demonstrated that patient cells divided up to 3 times whereas control cells divided up to 5 times. Gorska and Alam (2012) concluded that the UNC119 G22V mutation impairs LCK-dependent T-cell function.