CTG Expansion in the DMPK Gene: Semen Quality Assessment and Outcome of Preimplantation Genetic Diagnosis

Context: Myotonic dystrophy (DM) is an autosomal dominant disorder characterized mainly by myotonia but also by primary hypogonadism. No study has reported on fertility management of patients affected by DM type 1 (DM1).

Objective: This study investigates the impact of CTG repeats in the DMPK gene on semen quality and preimplantation genetic diagnosis (PGD) outcome.

Design: This is a monocentric retrospective observational study conducted from January 2003 to January 2019.

Setting: Antoine Béclère University Hospital, Clamart, France.

Patients: Three groups were compared in this study: male DM1 patients (Group A, n = 18), unaffected partners of DM1 female patients (Group B, n = 30), and proven fertile men (Group C, n = 33). Reproductive outcomes after PGD were compared between groups A and B.

Results: Sperm volume was reduced in group A (2.0 mL) when compared with groups B (3.0 mL; P < 0.01) and C (3.5 mL; P < 0.01). Progressive motility in raw sperm was also decreased in group A (30%) as compared to group C (40%; P < 0.01). The median number of progressive spermatozoa retrieved after sperm preparation was 2.7 million (M) in group A, which was significantly less than those of groups B (10.0 M; P < 0.01) and C (62.2 M; P < 0.01). Sperm motility was inversely correlated to the number of CTG repeats (Spearman r2 = 0.48, Pearson r2 = 0.35). Cumulative live birth rate per transfer was similar between groups, with 32.2% in group A versus 26.8% in group B.

Conclusions: As a precautionary measure, we advise physicians to perform regular monitoring of semen quality in affected males, which would allow sperm cryopreservation should semen parameters fall. PGD allows good reproductive outcomes without disease transmission.