Arthrogryposis–renal dysfunction–cholestasis syndrome

Arthrogryposis–renal dysfunction–cholestasis syndrome (ARC syndrome) is a rare genetic disorder characterized by arthrogryposis (joint contractures), renal tubular dysfunction, and cholestasis (a condition that impairs the release of a digestive fluid called bile from liver cells).

Symptoms

The symptoms of ARC syndrome can vary greatly from person to person. However, the three main features of the condition are:

• Arthrogryposis: This is a condition in which a child is born with joint contractures. This means some of their joints don't move as much as normal and may even be stuck in one position. Often, the muscles around these joints are thin, weak, stiff or missing. Extra tissue may have formed around the joint, holding it in place.

• Renal dysfunction: This refers to any condition in which the kidneys are not functioning as they should. In ARC syndrome, the renal dysfunction is usually in the form of proximal renal tubular acidosis, which is a condition that causes the kidneys to improperly reabsorb certain substances into the body, including bicarbonate, glucose, and amino acids.

• Cholestasis: This is a condition that impairs the release of a digestive fluid called bile from liver cells. In people with ARC syndrome, the cholestasis can lead to jaundice, pruritus (itching), and hepatomegaly (enlarged liver).

Causes

ARC syndrome is caused by mutations in the VPS33B or VIPAR gene. These genes provide instructions for making proteins that are involved in the trafficking of proteins and other materials within cells. Mutations in either of these genes disrupt this process, leading to the various signs and symptoms of ARC syndrome.

Diagnosis

The diagnosis of ARC syndrome is based on the presence of the characteristic signs and symptoms. Genetic testing can confirm the diagnosis.

Treatment

There is currently no cure for ARC syndrome. Treatment is supportive and based on the signs and symptoms present in each person.

Prognosis

The prognosis for individuals with ARC syndrome is generally poor, with most affected individuals not surviving past infancy.

See also

• Genetic disorder
• Rare disease

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