Acne, Adult

Acne is principally a disorder of adolescence but persists into middle age in a small minority of individuals. Goulden et al. (1999) quoted evidence, primarily from twin studies, suggesting that acne may be an inherited disorder. Clinically, the condition consists of a spectrum of diseases varying in age of onset and resolution as well as in severity, type, and distribution of lesions. It can be argued that, when investigating the inheritance of acne, particular subgroups must be considered separately. Goulden et al. (1999) investigated the familial risk of persistent adult acne by studying the occurrence of this condition in first-degree relatives of patients with adult persistent acne compared with the relatives of unaffected volunteers. In a study of 1,203 first-degree relatives of 204 adult acne cases and 856 first-degree relatives of 144 non-acne control volunteers, they found that adult acne was significantly greater among the relatives of a patient with adult acne than among relatives of an unaffected individual (odds ratio = 3.93, 95% CI 2.79-5.51; P less than 0.001).

To investigate the relative contribution of genetic and environmental factors on the liability to acne, Bataille et al. (2002) performed a large twin study based on 458 pairs of monozygotic and 1,099 pairs of dizygotic twins, all women with a mean age of 46 years. In addition, they assessed potential risk factors in twins with and without acne in a nested cross-sectional design. Fourteen percent of the twins reported a history of acne. Genetic modeling using acne scores showed that 81% (95% confidence interval 73-87%) of the variance of the disease was attributable to additive genetic effects. The remaining 19% was attributed to unique (i.e., unshared) environmental factors. Of the potential risk factors tested in 400 twins with acne and 2,414 unaffected twins, only apolipoprotein A1 (107680) serum levels were significantly lower in twins with acne even after adjusting for age and weight. Family history of acne was also significantly associated with an increased risk. No significant differences were found between twins with and without acne for weight, body mass index, height, birth weight, hair thinning, reproductive factors, cholesterol, triglycerides, high-density lipoprotein, or glucose levels. The lower serum levels of apolipoprotein A1 in twins with acne were also confirmed when analyzing acne-discordant twin pairs.