Homocystinuria (HCU) is a rare metabolic condition that occurs when the body can’t process a certain amino acid called methionine. This can cause a build-up of substances in the blood and urine that can be harmful.
In a person without HCU, our bodies can break down proteins we get from our food into amino acids like methionine. However, babies with HCU can’t fully break down methionine, leading to a buildup of methionine and another substance called homocysteine.
Common symptoms of HCU include:
Babies born with HCU may not initially show any symptoms. However, seeing a doctor as soon as you notice symptoms is essential. Untreated symptoms can lead to severe complications later in life, including a risk of brain damage. Children who are diagnosed and treated early can lead happy, healthy lives.
HCU is passed on through an inherited genetic mutation. The inheritance pattern for the abnormal HCU gene is autosomal recessive. This means that a baby needs to have an abnormal copy of the HCU gene from both parents to develop the disease.
Parents can carry an abnormal copy of the gene without knowing it, and a baby can receive only one affected gene and not develop HCU.
The only risk factor for HCU is having a family history of the disease.
Most babies are tested at birth for a variety of metabolic disorders, including HCU. A little blood is taken from your baby’s heel and tested for different disorders. If you were not tested for HCU as a baby, but your provider suspects you or your child has it, they’ll take a thorough medical history and ask about current symptoms.
They may perform a blood test and genetic testing to look for a buildup of methionine and the presence of the abnormal HCU gene.
Complications of HCU include brain damage, bone and joint disorders, stroke, and heart attack
HCU is treated in several different ways. Some babies are solely treated with vitamin B6 supplements. If this alone works to control HCU in your child, he or she will need to take vitamin B6 supplements for the rest of his or her life.
Other children may need to make diet alterations to reduce methionine intake. Their diet will be tailored to limit high-protein foods like meat, fish, and nuts. Most children with HCU work with a nutritionist to ensure that they’re getting what they need to develop correctly while managing the disorder. A diet may also be necessary for life.
Medicine may be prescribed later in life to help clear out excess homocysteine. HCU cannot be prevented.