MEGABLADDER, CONGENITAL; MGBL

Congenital megabladder (MGBL) is characterized by a massively dilated bladder with disrupted smooth muscle in the bladder wall. MGBL is a sex-limited trait with 95% male predominance, likely the result of differences in urethra and bladder development and length differences in urethra between males and females (Houweling et al., 2019).

▼ Clinical Features
Houweling et al. (2019) studied 3 families with congenital megabladder, including a large 4-generation family (family B) in which 8 males with megabladder died before birth and female obligate carriers were unaffected. In another family (family D), 2 affected males died prenatally and 1 was born with megabladder and agenesis of the right kidney; he developed end-stage renal failure and underwent kidney transplantation. In the third family (family C), megabladder was diagnosed prenatally in the male fetus and the pregnancy was terminated.

▼ Inheritance
Houweling et al. (2019) demonstrated autosomal dominant inheritance of congenital megabladder in 3 families. Incomplete penetrance was suggested in 1 of the families.

▼ Molecular Genetics
In 7 affected males from 3 families with congenital megabladder, Houweling et al. (2019) identified heterozygous mutations in the MYOCD gene (606127.0001-606127.0003). Five unaffected female carriers were also identified in 2 of the families. In addition, 1 unaffected male carrier was detected, suggesting incomplete penetrance.