Definition

Hartnup disease is an inherited nutritional disorder
with primary symptoms including a red, scaly rash and
sensitivity to sunlight.

Description

Hartnup disease was first identified in the 1950s in
the Hartnup family in London. A defect in intestines and
kidneys makes it difficult to break down and absorb protein
in the diet. This causes a condition very similar to
pellegra (niacin deficiency). The condition occurs in
about one of every 26,000 live births.

Causes and symptoms

Hartnup disease is an in-born error of metabolism,
that is, a condition where certain nutrients cannot be
digested and absorbed properly. The condition is
passed on genetically in families. It occurs when a person
inherits two recessive genes for the disease, one
from each parent. People with Hartnup disease are not
able to absorb some of the amino acids (the smaller
building blocks that make up proteins) in their
intestines. One of the amino acids that is not well
absorbed is tryptophan, which the body uses to make
its own form of niacin.

The majority of people with this disorder do not
show any symptoms. About 10