Question: What are the genetic changes related to congenital fiber-type disproportion ?
Answer: Mutations in multiple genes can cause congenital fiber-type disproportion. Mutations in the TPM3, RYR1 and ACTA1 genes cause 35 to 50 percent of cases, while mutations in other genes, some known and some unidentified, are responsible for the remaining cases. The genes that cause congenital fiber-type disproportion provide instructions for making proteins that are involved in the tensing of muscle fibers (muscle contraction). Changes in these proteins lead to impaired muscle contraction, resulting in muscle weakness. Skeletal muscle is made up of two types of muscle fibers: type I (slow twitch fibers) and type II (fast twitch fibers). Normally, type I and type II fibers are the same size. In people with congenital fiber-type disproportion, type I skeletal muscle fibers are significantly smaller than type II skeletal muscle fibers. It is unclear whether the small type I skeletal muscle fibers lead to muscle weakness or are caused by muscle weakness in people with congenital fiber-type disproportion.
Source: GHR

Question: What are the treatments for congenital fiber-type disproportion ?
Answer: These resources address the diagnosis or management of congenital fiber-type disproportion: - Gene Review: Gene Review: Congenital Fiber-Type Disproportion - Genetic Testing Registry: Congenital myopathy with fiber type disproportion - MedlinePlus Encyclopedia: Contracture Deformity - MedlinePlus Encyclopedia: Hypotonia These resources from MedlinePlus offer information about the diagnosis and management of various health conditions: - Diagnostic Tests - Drug Therapy - Surgery and Rehabilitation - Genetic Counseling - Palliative Care
Source: GHR