Final answer:
Congenital anemias refer to inherited anemias present from birth. Missing thumbs and triphalangeal thumbs are two types of congenital anemias that affect the thumb. Missing thumbs result in underdeveloped or absent thumbs, while triphalangeal thumbs have an extra bone in the thumb.
Step-by-step explanation:
Congenital anemias refer to a group of inherited anemias that are present in individuals from birth. There are different types of congenital anemias, including the ones that manifest as missing thumbs or triphalangeal thumbs. Missing thumbs, also known as thumb hypoplasia, is a condition where the thumbs are underdeveloped or absent. On the other hand, triphalangeal thumbs have an extra phalanx bone in the thumb. These conditions can be caused by genetic mutations or chromosomal abnormalities.