Novel biallelic ADCY10 variants cause asthenozoospermia with excessive residual cytoplasm and hydronephrosis in humans.

RESEARCH QUESTION: Could the novel mutations in ADCY10 cause asthenozoospermia and absorptive hypercalciuria in humans, and the potential pathogenesis?

DESIGN

Whole-exome sequencing and Sanger sequencing were conducted to identify potential pathogenic variants in two unrelated Pakistani families. Reverse transcription polymerase chain reaction was utilized to assess the mutation effect on mRNA levels in the patients. Transmission electron microscopy and scanning electron microscopy were performed to examine the sperm flagellar ultrastructure. Western blot and immunofluorescence assays were performed to evaluate the expression and localization of ADCY10 and other axonemal components.

RESULTS

Three novel ADCY10 variants were identified in two unrelated Pakistani families. Patient 1 (P1) and P2 from Family 1 carried compound heterozygous mutation c.2902C>T (p. Arg968*) and c.4286+1G>T, and P3 and P4 from Family 2 carried homozygous mutation c.436+2T>G. These patients suffered from male infertility with compromised sperm motility and hydronephrosis with kidney stones. No ADCY10 mRNA and ADCY10 protein were detected in the blood and sperm lysate of the patients. Morphological analyses revealed obvious mid-piece defects along with head anomalies in the patients' spermatozoa. Transmission electron microscopy and immunofluorescence assay showed excessive residual cytoplasm in the mitochondrial sheath and misarranged mitochondrial sheath structures in the patients, indicating a novel role of ADCY10 in regulating the proper organization of the mitochondrial sheath.

CONCLUSIONS

These results indicate that ADCY10 is an important factor for maintaining the proper structure of the mitochondrial sheath and motility of spermatozoa, which extends the phenotype spectrum of ADCY10 loss-of-function mutations in humans.