Hirsutism can run in families due to genetics

Hirsutism is a medical condition defined as excessive and unwanted hair in a male-like formulation in various androgen-sensitive body parts (face and/or neck, chest and lower abdomen etc) in women. Studies suggest that it affects between 5 percent and 15 percent of women, varying according to characteristics and at least 5 percent of women of reproductive age suffer from this problem.

Hirsutism is usually a manifestation of an underlying endocrine disorder that results in androgen over activity. There are non-androgenic causes as well, though they are rare.

This disorder that results in significant psychological stress is often marked by a strong familial factor. In Lorenzo’s study of hirsutism (refer to Lorenzo EM. Familial study of hirsutism) the familial trait has been elaborately evaluated. This study was conducted on 300 random untreated cases (irrespective of racial differences) from a public health survey group in Michigan. Its score pattern was based on only five body regions namely chin, upper lip, chest, abdomen, and thighs and the count was the conventional 0 to 4. This survey recorded a hirsutism tally over 5 among many of the cases studied.

This familial survey based their results on 90 hirsute ‘probands’ and their families. The first step to this study was to get hold of a family history of all the patients. Thereafter, volunteering mothers and sisters underwent a partial medical test, but only of the facial area. This group also underwent a full evaluation of hirsutism and other androgenic examinations.

Results of the investigation:

• Increased prevalence of hirsutism among the female relatives
• Acne and/or frontal balding among the male family members of the hirsute cases under survey

The high incidence of familial traits of hirsutism was the conclusion. This hereditary propensity led to the following propositions:

1. Many of the endocrine related causes of hirsutism show a marked genetic trait, especially in the most common cause of PCOS.
2. The biological factors behind hirsutism and hair production (for instance androgen receptor actions, 5a-reductase activity) may also vary according to genetic make-up.

The strong genetic variations of hirsutism can be best adjudged in patients with sparse terminal body hair combined with androgen receptor insensitivity and 5a-reductase inadequacy. This is similarly noted in the much lesser intensity of hirsutism seen in Asian cases with PCOS despite similar circulating androgen levels.
A frequent genetic adaptation that experts suggest could alter the androgen receptor activity is the number of trinucleotide CAG repeats in exon 1 of the androgen receptor gene. Studies have suggested that these trinucleotide repeats differ substantially (i.e., be polymorphic) among humans.

According to an expert view, the CAG codons encode for a long stretch of glutamines within the amino terminal of the transactivation domain of the androgen receptor.

Shorter CAG repeat lengths in the N-terminal domain of the androgen have also been suggested in the formation of hirsutism although it is debated as well. For instance in a study conducted by Vottero and colleagues, they did not find a variation in the number of CAG repeats between hirsute cases and controls and found no link between number of repeats and the Ferriman and Gallwey score of evaluating hirsutism. They rather reported that in the peripheral blood lymphocytes of 16 idiopathic hirsute cases the longer of the two-androgen receptor alleles (i.e., possibly the less powerful one) was preferentially methylated (and hence non-functional). Hence, they concluded that genetic modifications of the androgen receptor action and probably 5a-reductase activities can alter the manifestation of hirsutism.