Meromelia

Meromelia is a birth defect characterized by the absence of part, but not all, of one or more limbs, with a hand or foot nonetheless present at the end of the affected limb, producing a shrunken or deformed extremity rather than a completely missing one. This partial-absence pattern distinguishes meromelia from amelia, the complete absence of a limb, since the recognizable presence of a terminal hand or foot is the condition's defining feature. The condition arises primarily from genetic disorders affecting limb development, though environmental factors are also documented causes; the best-known environmental cause is thalidomide, a drug used between 1957 and 1962 to treat morning sickness in pregnant women, which produced well-documented cases of this kind of limb deficiency in children born to women who took it during pregnancy. The historical thalidomide episode remains one of the most widely studied examples connecting a specific environmental exposure to a defined pattern of congenital limb malformation, and it continues to inform how clinicians and researchers think about drug safety during pregnancy.