Cryptorchidism: Novel genetic insights into CCDC149 mutations.

Background: Cryptorchidism, characterized by the failure of one or both testes to descend into the scrotum, is a common congenital condition that can lead to infertility and increased risk of testicular cancer. CCDC149, a coiled-coil domain-containing protein, has been implicated in various developmental processes, but its role in the male reproductive system remains unexplored.

Objective: This study aims to investigate the role of CCDC149 mutations in the development of bilateral cryptorchidism and to elucidate the underlying molecular mechanisms.

Materials and methods: We conducted a whole-exome sequencing of an 8-year-old boy diagnosed with bilateral cryptorchidism, revealing a mutation in the CCDC149 gene. To further explore the functional implications of this mutation, we utilized CRISPR/Cas9 technology to generate Ccdc149 knockout mice. The phenotypic characteristics of these mice were assessed, focusing on testicular descent and sperm morphology. Additionally, single-cell RNA sequencing was performed to analyze the expression of genes associated with CCDC149, including anti-Müllerian hormone (AMH) and muscle-related factors.

Results: The Ccdc149 knockout mice exhibited significant phenotypic traits consistent with cryptorchidism, including undescended testes and oligoasthenoteratozoospermia. Single-cell RNA sequencing analysis revealed altered expression patterns of AMH and several muscle-related genes, suggesting a potential regulatory interaction between CCDC149, AMH, and muscle development factors in the context of testicular descent.

Discussion: Our findings provide novel genetic insights into the role of CCDC149 mutations in cryptorchidism. The observed phenotypic characteristics in the knockout mice, along with the gene expression analysis, indicate that CCDC149 may be crucial for normal testicular descent through its interaction with AMH and muscle-related factors. These results highlight the importance of further research into the molecular mechanisms underlying cryptorchidism, which could lead to improved diagnostic and therapeutic strategies for affected individuals.