<unk> (from Greek α = "none" plus μέλος (plural μέλεα) = "limb") is the birth defect of lacking one or more limbs. It can also result in a shrunken or deformed limb. For example, a child might be born without an elbow or forearm.
Amelia 
Histidinemia
Isovaleric acidemia
Hyperoxaluria
Hypermethioninemia
Galactosemia
Hyperammonemia
Xanthinuria