Dysmelia
Dysmelia (from the Greek dys (δυσ-), "bad" + mélos (μέλος), "limb" + English suffix -ia) is a congenital disorder of a limb resulting from a disturbance in embryonic development.

Types
Dysmelia can refer to
missing (aplasia) limbs: amelia, oligodactyly, congenital amputation e.g. tibial or radial aplasia
malformation of limbs: shortening (micromelia, rhizomelia or mesomelia), ectrodactyly, phocomelia, meromelia, syndactyly, brachydactyly, club foot
too many limbs: polymelia, polydactyly, polysyndactyly
others: tetraamelia, hemimelia, symbrachydactyly

Occurrence rate
Birth defects involving limbs occur in 1 per 1000.

Causes
Dysmelia can be caused by
Inheritance of abnormal genes, e.g. polydactyly, ectrodactyly or brachydactyly, symptoms of deformed limbs then often occur in combination with other symptoms (syndromes)
external causes during pregnancy (thus not inherited), e.g. via amniotic band syndrome
teratogenic drugs (e.g. thalidomide, which causes phocomelia) or environmental chemicals
ionizing radiation (nuclear weapons, radioiodine, radiation therapy)
infections
metabolic imbalance

Syndromes with dysmelia
References
External links
DysNet: An organisation for people affected by Dysmelia (congenital limb difference)
Reach: Association for Children with Upper Limb Deficiency)