Fukuyama type congenital muscular dystrophy (FCMD) is an autosomal recessive muscular dystrophy associated with an anomaly of the brain. We performed genetic linkage analyses using consanguineous FCMD families and localized the FCMD locus to chromosomes 9q31-33. We further defined the locus within a region of 5 cM and also found strong linkage disequilibrium between FCMD and mfd220. We suspect that the FCMD gene could lie within one megabases of the mfd220 locus located on 9q31. This achievement made prenatal and carrier diagnosis in families carrying FCMD feasible. However, in principle, it is impossible to diagnose whether a patient has FCMD or not, since this is an indirect genetic diagnosis by polymorphisms analysis. It has been discussed whether FCMD and Walker-Warburg syndrome (WWS) belong to the same disease entity or not. We analyzed a family in which 3 siblings were affected with either FCMD or WWS. The results suggested that both FCMD and WWS siblings shared the identical combination of mutations on either allele of the FCMD locus. Some WWS cases could be caused by mutations in the FCMD gene. A novel clinical entity of merosin-negative CMD was proposed out of classical, non-Fukuyama CMD cases. This condition mapped to 6q2, the merosin gene region. CMD researches are in rapid progress.