arthrogryposis, distal, type 1B

Arthrogryposis, distal, type 1B is a condition marked by congenital joint contractures that primarily affect the hands and feet. It falls within the spectrum of distal arthrogryposis disorders and is associated with variants in the MYBPC1 gene. The condition is inherited in an autosomal dominant pattern, meaning that a single altered copy of the gene can cause the disorder. Because precise prevalence estimates are not available, it is understood to be a rare condition identified primarily through clinical evaluation in infancy.

Individuals with arthrogryposis, distal, type 1B typically present with distal arthrogryposis, which is observed in all affected cases. Many also exhibit foot joint contractures, while a significant proportion experience talipes equinovarus and joint contractures of the hand, and a smaller subset may have a rocker bottom foot. Not all individuals experience all these features, and the severity and range of symptoms can vary considerably. Early identification often occurs during infancy when limited joint mobility and stiffness become apparent.

This condition is caused by pathogenic variants in the MYBPC1 gene, which is important for normal muscle structure and function. It is inherited in an autosomal dominant pattern, meaning that an affected individual carries one altered copy of the gene and has a 50% chance of passing it on to their children. Due to variable expressivity, even family members with the same variant can experience a different range and severity of symptoms. Genetic counseling is recommended to help families understand the inheritance pattern and implications for future family planning.

Currently, management of arthrogryposis, distal, type 1B focuses on supportive care and symptom management tailored to each individual’s needs. A multidisciplinary approach is often employed, involving physical therapy, occupational therapy, and other rehabilitative services to help improve joint mobility and overall function. As there are no treatments that are specifically approved for this condition, care is centered on optimizing quality of life. Patients are encouraged to discuss treatment options and supportive strategies with their healthcare team as well as to seek genetic counseling for further guidance.

The long-term outlook for individuals with arthrogryposis, distal, type 1B varies widely depending on the severity of joint contractures and the effectiveness of supportive treatments. Many affected individuals achieve significant improvements in function and mobility through early intervention and ongoing therapy, although some may continue to experience challenges related to joint stiffness over time. Outcomes described in medical literature continue to evolve as standards of care improve, and families are encouraged to connect with expert centers and genetic counselors for personalized guidance and support.