Three human diseases cosegregate with microsatellite markers used in construction of the human BAC/YAC physical map, including autosomal dominant nocturnal frontal lobe epilepsy (ENFL2; also known as ADNFLE), a syndrome of mental retardation, spasticity, and tapetoretinal degeneration (MRST); and a pyogenic arthritis, pyoderma gangrenosum, and acne syndrome (PAPA).