Reproduction Function in Male Patients with Bardet Biedl Syndrome

Purpose: Bardet-Biedl syndrome (BBS) is a ciliopathy with a wide spectrum of symptoms due to primary cilia dysfunction including genitourinary developmental anomalies as well as impaired reproduction particularly in males. Primary cilia are known to be required at the following steps of reproduction function: (1) genitourinary organogenesis, (2) in the fetal firing of hypothalamo-pituitary axe, (3) sperm flagellum structure and (4) the first zygotic mitosis conducted by proximal sperm centriole. BBS phenotype is not fully understood.

Methods: This study explored all steps of reproduction in 11 French male patients with identified BBS mutations.

Results: BBS patients presented frequently genitourinary malformations as cryptorchidism (5/11), short scrotum (5/8), micropenis (5/8) but unexpectedly, normal testis size (7/8). Ultrasonography highlighted epididymal cysts or agenesis of one seminal vesicle in some cases. Sexual hormones levels were normal in all patients except one. Sperm numeration was normal in 8 out of the 10 obtained samples. Five to 45% of sperm presented a progressive motility. Electronic microscopy did not reveal any homogeneous abnormality. Moreover, a psychological approach pointed a decreased self-confidence linked to blindness and obesity explaining why so few BBS patients express a child wish.

Conclusions: PC dysfunction in BBS impacts embryology of the male genital tract, especially epididymis, penis and scrotum through an insufficient fetal androgen production. However, in adults, sperm structure does not seem to be impacted. These results should be confirmed in a greater BBS patient cohort, focusing on fertility.