CDKN2A and familial congenital mirror movements: CDKN2B, located about 30 kb centromeric from CDKN2A and coding the cyclin-dependent kinase inhibitor p15INK4b, was the first obvious candidate gene but has been excluded as being a high penetrance susceptibility gene for CMM (Platz et al, 1997; Laud et al, 2006).