Limb-Girdle Muscular Dystrophy, Type 2I (FKRP)
Limb-girdle muscular dystrophy, type 2I is an autosomal recessive disorder that is caused by pathogenic variants in the gene FKRP. While it is found in different ethnicities around the world, it is more prevalent in individuals of Norwegian descent. The age of onset of this form of muscular dystrophy is variable, with symptoms presenting between the ages of 1 and 40 years. Clinical features include weakness of the hip and shoulder girdle, difficulty walking, spinal abnormalities including scoliosis, lordosis and kyphosis, and cardiomyopathy. Patients may also experience difficulty breathing. However, the severity varies between patients, with some never requiring a wheelchair. Life expectancy is unknown, although most patients with limb-girdle muscular dystrophies have a shorter than natural life-span. Pathogenic FKRP variants can also result in two rare, more severe disorders, known as Walker-Warburg syndrome and muscular dystrophy-dystroglycanopathy, congenital with or without mental retardation. These disorders have their onset at birth and may involve severe brain malformations. Currently, it is not possible to predict the severity of the disease based on the inherited variants.
For information about carrier frequency and residual risk, please see the residual risk table.