inborn errors of the metabolism

In another group of inborn errors of the metabolism the
signs and symptoms are due to deficiency of the end product of
a metabolic reaction, and treatment depends on replacing this
end product. Defects occurring at different stages in
biosynthesis of adrenocortical steroids in the various forms of
congenital adrenal hyperplasia are treated by replacing cortisol,
alone or together with aldosterone in the salt losing form.
Congenital hypothyroidism can similarly be treated with
thyroxine replacement. In some disorders, such as
oculocutaneous albinism in which a deficiency in melanin
production occurs, replacing the end product of the metabolic
pathway is, however, not possible.