Autosomal recessive osteopetrosis type 1 (ARO1) is a hereditary disorder characterized by abnormal bone development, often noticeable during infancy.
Common traits include dense bones, susceptibility to fractures, an enlarged head with a pronounced forehead, stunted growth, and dental complications. The cranial bone anomalies can exert pressure on facial nerves, potentially leading to visual impairment, deafness, and facial muscle paralysis. Constricted airways and feeding passages may also cause breathing and eating challenges. ARO1’s impact extends to the bone marrow, crucial for blood cell and immune system maturation, resulting in severe anemia, heightened infection vulnerability, liver and spleen enlargement, and possibly mild to moderate intellectual disability due to recurring seizures and brain abnormalities.
ARO1 is caused by pathogenic (disease-causing) variants in the TCIRG1 gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 350 chance to be a carrier.
Other names for this condition are congenital osteopetrosis and marble bone disease.
Resources:
National Organization of Rare Disorders
Revised August 2023
