CCR5 genotyping in an Australian and New Zealand type 1 diabetes cohort

Infiltration of pancreatic tissue by autoreactive T-cells involves secretion of multiple cytokines and chemokine receptor expression. Genetically determined variation in cell surface expression of the chemokine receptor CCR5 may result in differences in inflammatory cell migration in response to relevant chemokines. Adolescents with type 1 diabetes (T1D) from Australia and New Zealand were genotyped for CCR5-delta32 (n = 626). The allele frequency was compared with that of 253 non-diabetic Australian adolescents and with that of 92 adults with systemic lupus erythematosus. A reduced allele frequency was seen in T1D compared with controls (0.092 vs. 0.123, p = 0.05). This difference was not seen for the cohort of patients with SLE (freq = 0.114). A reduction in the number of CCR5-delta32/delta32 homozygotes, who lack CCR5, in the T1D cohort was also seen and while not statistically significant (2 observed compared to 5.25 expected; p = 0.12) is interesting. These results suggest a partial protection from T1D for CCR5-delta32 homozygous individuals is possible and that CCR5 has a potential role in the pathogenesis of T1D.