Alkaptonuria, also known as AKU or Black Bone Disease, is an extremely rare genetic condition, which can cause significant damage to the bones, cartilage and tissues of those affected. AKU normally only affects one in every 250,000 people worldwide. AKU is a recessive condition that is caused by a mutation of each of a pair of chromosomes, this means that if two people carry the faulty gene, their child still only has a 25% chance of developing AKU.
AKU stops patients’ bodies from breaking down a chemical called homogentisic acid (HGA) which the body naturally produces during the digestion of food. Due to this, HGA builds up in the body and, over time, leads to black and brittle bones and cartilage, and early onset osteoarthritis. The build-up of HGA in the body can also lead to other, sometimes more serious health complications.¹
HGA is broken down by an enzyme coded by a gene on chromosome 3. Humans have a pair of chromosomes 3. AKU is a recessive condition that is caused by a mutation of the HGA-degrading genes in both chromosomes 3. This means that if two people carry the faulty gene (have one faulty gene and one normal gene), their child has a 25% chance of developing AKU.
Published: 27.02.23 Next review: 27.02.26