Androgen receptor CAG repeat polymorphism might be a possible cause of familial constitutional delay of growth and puberty.

Abstract

Background: Induction of puberty in boys with constitutional delay of growth and puberty (CDGP) through a short course of low-dose testosterone therapy indicates the critical interaction between testosterone and the androgen receptor (AR) during the activation and maturation of the hypothalamic-pituitary-gonadal axis at puberty onset. Previous studies have shown an inverse relationship between the CAG repeat length and the transactivation function or expression level of the AR gene.

Objective: We aimed to investigate whether the AR CAG repeat polymorphism has any implications on pubertal delay.

Subjects and methods: Thirty-three male patients with CDGP were enrolled in the study group, while 53 age-matched healthy individuals who had entered puberty on time were included in the control group. The CAG repeat length was determined through direct DNA sequencing analysis.

Results: The median chronological age of boys with CDGP was 14.2 (14.1-14.6) years, compared to 14.2 (13.65-14.8) years for healthy subjects (p = 0.5). In the CDGP group, 22 (66.7%) children had a family history of the condition. There was no significant difference between the groups in terms of AR CAG repeat length (median AR CAG repeat length: 21 (20-24.5) and 20 (20-24), respectively, p = 0.1). However, in boys with CDGP with a similar family history (n = 22), a significantly longer AR CAG repeat length was found compared to the control group (n = 53) (median AR CAG repeat length: 22 (20-25) and 20 (20-24), respectively, p = 0.03). The median AR CAG repeat length in boys without a family history was 21 (20-22) triplets. Although boys with a family history had a slightly longer AR CAG repeat length than those without, the difference was not statistically significant (p = 0.07). Additionally, no significant differences were observed between boys with non-familial CDGP and control subjects (p = 0.8). Furthermore, no significant differences in anthropometric characteristics or hormonal parameters were found when patients with CDGP were categorized by AR CAG repeat length quartiles.

Conclusion: This is the first study to investigate the role of AR CAG polymorphism in the etiopathogenesis of CDGP. Our findings suggest that the AR CAG repeat length may be associated with familial CDGP.