CHD7 missense variants and clinical characteristics of Chinese males with infertility

Isolated hypogonadotropic hypogonadism (IHH) and Kallmann syndrome (KS) are rare genetic diseases that cause male infertility. The chromodomain helicase DNA-binding protein 7 (CHD7) gene is commonly associated with KS and IHH. We speculated that CHD7 variants may be associated with male infertility.

Two hundred males with azoospermia and 120 with oligozoospermia were recruited. The patients underwent clinical examination and reproductive hormone testing. A panel of genes including CHD7 and others related to spermatogenic failure was sequenced by targeted-gene exome sequencing.

Three patients with severe oligozoospermia had CHD7 variants (a detection rate of 0.94% (3/320)). After prediction software analysis, two of the variants c.3464G>A (p.R1155H) and c.4516G>A (p.G1506S) were predicted to be likely pathogenic. Although predicted to be benign, the variants of c.2824A>G (p.T942A) located in the chromodomain 2 could not be excluded as disease causing. The patients with variants had small testicular volumes. In particular, the testes of the patient with a p.G1506S variant varied in size (left, 8 ml; right, 4.5 ml). Two patients (patients 31 and 120) had low E2 levels and two (patients 83 and 120) had low T levels. Ultimately, these variants were classified as "variants of unknown significant" that may be associated with male infertility.

There may be a relationship between the CHD7 gene missense variants and male infertility. These variants are easier to find in patients with azoospermia and severe oligospermia whose testosterone levels are decreased.