Male hypogonadism in myotonic dystrophy is related to (CTG)n triplet mutation.

The Authors considered the relationship between hypogonadism in myotonic dystrophy (MD) and MT-PK gene mutation. Twenty-seven subjects were studied, and the (CTG)n amplification varied from 70 to 1520 (mean 661 +/- 463). Hypergonadotropic-hypogonadism with LH levels of 6.94 +/- 3.87 and FSH 14.54 +/- 9.58 IU/L was present; testosterone still showed normal values (505.7 +/- 376.2 ng/dl), but 44.4% of patients had abnormal serum level less than 250 ng/dl. We found a significant correlation (p < 0.001) between CTG repeat size and levels of both LH and FSH: these findings suggest that the severity of hypogonadism is related to MT-PK gene mutation.