Association of insulin-like growth factor (IGF)-1 gene polymorphisms with plasma levels of IGF-1 and acne severity

Abstract

Polymorphisms of the insulin-like growth factor (IGF)-1 gene consisting of variable cytosine adenosine repeats in the promoter region may directly influence the expression of IGF-1. We sought to assess the role of IGF-1 gene polymorphisms in determination of plasma IGF-1 levels, acne, and its severity. In this case-control study, 80 patients with acne vulgaris of 4 severity grades as per Global Acne Grading System and 80 age- and gender-matched control subjects without acne were studied. All the study subjects were without any disorder or a history of drug intake likely to affect IGF-1 level within a year before the study inclusion date. IGF-1 polymorphism was determined by polymerase chain reaction and plasma levels of IGF-1 by enzyme-linked immunosorbent assay. Acne severity was assessed by Global Acne Grading System. Mean plasma IGF-1 level in acne cases was significantly higher than in non-acne controls (P=.04). Plasma IGF-1 level positively correlated with severity of acne (P=.01). Individuals homozygous for the 192-base pair (bp) allele had 4.29 times odds risk (95% confidence interval 1.38-13.33) of having acne and a significantly higher mean level of IGF-1 compared with non-192/non-192 participants. Individuals homozygous for the 192-bp allele had 3.08 times odds risk (95% confidence interval 1.15- 8.31) of having higher severity grade of acne compared with non-192/non-192 participants. A relatively small number of participants were studied. Plasma IGF-1 levels positively correlate with severity of acne. The 192/192 homozygotes had higher risk of acne and higher severity grade of acne. Functional studies showing the relationship between IGF-1 promoter level polymorphism and actual gene expression in skin are warranted.