No Association of Androgen Receptor GGN Repeat Length Polymorphism With Infertility in Indian Men

Abstract

Androgens, acting through the androgen receptor (AR), play a role in secondary sexual differentiation from the prenatal stage to adulthood, including spermatogenesis. The AR gene has 2 polymorphic trinucleotide repeats (CAG and GGN) in exon 1. The CAG repeat length polymorphism has been well studied in a variety of medical conditions, including male infertility. Many of these studies have shown an association of the expanded CAG repeats with male infertility, although this is not true for all populations. The GGN repeat, in contrast, has been less thoroughly studied. Thus far, only 4 reports worldwide have analyzed the GGN repeat, alone or in combination with the CAG repeat, in male infertility cases. No such study has been undertaken on infertile Indian men. Therefore, we have analyzed AR-GGN repeats in a total of 595 Indian males,

Non-linear association between androgen receptor CAG and GGN repeat lengths and reproductive parameters in fertile European and Inuit men

“…For example, short GGN repeats have been associated with lower semen volume (Lundin et al, 2006), whereas increased GGN repeat length has been observed among boys with penile hypospadias and in men with cryptorchidism (Aschim et al, 2004;Radpour et al, 2007). Both we (Lundin et al, 2003) and others (Rajender et al, 2006;Tut et al, 1997) reported no significant differences in distributions of GGN repeat lengths between infertile and fertile men, while in other studies an association between GGN repeat length and infertility was observed only in combination with certain CAG repeat lengths (Ferlin et al, 2004;Ruhayel et al, 2004).…”

No Correlation between Androgen Receptor CAG and GGN Repeat Length and the Degree of Genital Virilization in Females with 21-Hydroxylase Deficiency

“…In contrast, other studies found a decreased sperm volume in males with an nGGn less than 23 but no influence of the GGn repeat length on sperm count (28,29). Moreover, a large investigation on Indian males (n ϭ 595) found no difference of GGn length between fertile and infertile subjects (30); however, a significant difference of GGn repeat length in patients with penile hypospadias and cryptorchidism was reported (31).…”

The number of CAG and GGN triplet repeats in the Androgen Receptor gene exert combinatorial effect on hormonal and sperm parameters in young men

“…The association was further supported by the most recent meta-analysis including 40 studies (3858 cases and 3161 controls) published from 2000 to 2015 (Xiao et al, 2016). In contrast to the length of the CAG stretch, no significant association with male infertility has been identified for the GGN-tract length (Tut et al, 1997;Rajender et al, 2006). In contrast to the length of the CAG stretch, no significant association with male infertility has been identified for the GGN-tract length (Tut et al, 1997;Rajender et al, 2006).…”