The document discusses three types of inborn errors of metabolism: phenylketonuria, which is caused by a recessive gene preventing the conversion of phenylalanine to tyrosine, leading to accumulation of phenylalanine derivatives; alkaptonuria, caused by a recessive gene preventing the conversion of homogentistic acid, turning the urine black; and albinism, a recessive condition preventing the production of the enzyme tyrosinase needed to produce melanin pigment.