Sex steroid hormones and sex hormone binding globulin levels, CYP17 MSP AI (−34 T:C) and CYP19 codon 39 (Trp:Arg) variants in children with developmental stuttering

- There was an association between stuttering and serum levels of testosterone, DHT and oestradiol.
- Stuttering was not associated with digit ratio (2D:4D), an estimation of foetal exposure to testosterone.
- The frequency of an allele of the CYP17 −34 T:C polymorphism was associated with susceptibility to stuttering.

Developmental stuttering is known to be a sexually dimorphic and male-biased speech motor control disorder. In the present case-control study, we investigated the relationship between developmental stuttering and steroid hormones. Serum levels of testosterone, dihydrotestosterone (DHT), dehydroepiandrosterone (DHEA), oestradiol, progesterone, cortisol, and sex hormone binding globulin (SHBG), as well as the 2nd/4th digit ratio (2D:4D), an indicator of prenatal testosterone level, were compared between children who stutter (CWS) and children who do not stutter (CWNS). Moreover, two SNPs (CYP17 −34 T:C (MSP AI) and CYP19 T:C (Trp:Arg)) of cytochrome P450, which is involved in steroid metabolism pathways, were analysed between the groups. Our results showed significantly higher levels of testosterone, DHT, and oestradiol in CWS in comparison with CWNS. The severity of stuttering was positively correlated with the serum levels of testosterone, DHEA, and cortisol, whereas no association was seen between the stuttering and digit ratio, progesterone, or SHBG. The CYP17CC genotype was significantly associated with the disorder.