Toward a Robust Definition of Sport Sex

Elite individual sports in which success depends on power, speed, or endurance are conventionally divided into male and female events using traditional binary definitions of sex. Male puberty creates durable physical advantages due to the 20- to 30-fold increase in circulating testosterone producing a sustained uplift in men's muscle, bone, hemoglobin, and cardiorespiratory function resulting from male puberty and sustained during men's lives. These male physical advantages provide strong justification for a separate protected category of female events allowing women to achieve the fame and fortune from success they would be denied if competing against men. Recent wider social acceptance of transgender individuals, together with the less recognized involvement of intersex individuals, challenge and threaten to defeat the sex classifications for elite individual female events. This can create unfair advantages if seeking inclusion into elite female events of unmodified male-bodied athletes with female gender identity who have gained the physical advantages of male puberty. Based on reproductive physiology, this paper proposes a working definition of sport sex based primarily on an individual's experience of male puberty and can be applied to transgender and various XY intersex conditions. Consistent with the multidimensionality of biological sex (chromosomal, genetic, hormonal, anatomical sex), this definition may be viewed as a multistrand cable whose overall strength survives when any single strand weakens or fails, rather than as a unidimensional chain whose strength is only as good as its weakest link.

Disorder of Sex Development Due to 17-Beta-Hydroxysteroid Dehydrogenase Type 3 Deficiency: A Case Report and Review of 70 Different HSD17B3 Mutations Reported in 239 Patients

The 17-beta-hydroxysteroid dehydrogenase type 3 (17-β-HSD3) enzyme converts androstenedione to testosterone and is encoded by the HSD17B3 gene. Homozygous or compound heterozygous HSD17B3 mutations block the synthesis of testosterone in the fetal testis, resulting in a Disorder of Sex Development (DSD). We describe a child raised as a female in whom the discovery of testes in the inguinal canals led to a genetic study by whole exome sequencing (WES) and to the identification of a compound heterozygous mutation of the HSD17B3 gene (c.608C>T, p.Ala203Val, and c.645A>T, p.Glu215Asp). Furthermore, we review all HSD17B3 mutations published so far in cases of 17-β-HSD3 deficiency. A total of 70 different HSD17B3 mutations have so far been reported in 239 patients from 187 families. A total of 118 families had homozygous mutations, 63 had compound heterozygous mutations and six had undetermined genotypes. Mutations occurred in all 11 exons and were missense (55%), splice-site (29%), small deletions and insertions (7%), nonsense (5%), and multiple exon deletions and duplications (2%). Several mutations were recurrent and missense mutations at codon 80 and the splice-site mutation c.277+4A>T each represented 17% of all mutated alleles. These findings may be useful to those involved in the clinical management and genetic diagnosis of this disorder.

46,XY disorder of sex development (DSD) due to 17β-hydroxysteroid dehydrogenase type 3 deficiency

17β-hydroxysteroid dehydrogenase 3 deficiency consists of a defect in the last phase of steroidogenesis, in which androstenedione is converted into testosterone and estrone into estradiol. External genitalia range from female-like to atypical genitalia and most affected males are raised as females. Virilization in subjects with 17β-HSD3 deficiency occurs at the time of puberty and several of them change to male social sex. In male social sex patients, testes can be safely maintained, as long as they are positioned inside the scrotum The phenotype of 46,XY DSD due to 17β-HSD3 deficiency is extremely variable and clinically indistinguishable from other causes of 46,XY DSD such as partial androgen insensitivity syndrome and 5α-reductase 2 deficiency. Laboratory diagnosis is based on a low testosterone/androstenedione ratio due to high serum levels of androstenedione and low levels of testosterone. The disorder is caused by a homozygous or compound heterozygous mutations in the HSD17B3 gene that encodes the 17β-HSD3 isoenzyme leading to an impairment of the conversion of 17-keto into 17-hydroxysteroids. Molecular genetic testing confirms the diagnosis and provides the orientation for genetic counseling. Our proposal in this article is to review the previously reported cases of 17β-HSD3 deficiency adding our own cases.