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FKTN gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

FKTN gene

The FKTN gene provides instructions for making the enzyme fukutin, which is vital for the glycosylation of alpha-dystroglycan and the maintenance of muscle and brain tissue.

Normal Function

The FKTN gene provides instructions for making an enzyme called fukutin. This enzyme is present in many of the body's tissues, but it is particularly abundant in the heart, brain, and the muscles used for movement (skeletal muscles). Within cells, fukutin is found in a specialized structure called the Golgi apparatus, where newly produced proteins are modified.

Fukutin is involved in a protein modification process called glycosylation. Through this chemical process, sugar molecules are added to certain proteins. Fukutin works closely with other enzymes to add ribitol phosphate molecules to the chain of sugars already attached to a protein called alpha-dystroglycan. Glycosylation is critical for the normal function of alpha-dystroglycan.

The alpha-dystroglycan protein helps anchor the structural framework inside each cell (cytoskeleton) to a network of molecules outside the cell (extracellular matrix). In skeletal muscles, alpha-dystroglycan helps stabilize and protect muscle fibers. In the brain, alpha-dystroglycan helps direct the movement (migration) of nerve cells (neurons) during early development.

Health Conditions Related to Genetic Changes

Fukuyama congenital muscular dystrophy

Several different variants in the FKTN gene have been found to cause Fukuyama congenital muscular dystrophy, a condition that affects the development of the eyes, brain, and skeletal muscles. This form of congenital muscular dystrophy occurs primarily in people of Japanese ancestry.

Most people with Fukuyama congenital muscular dystrophy have at least one copy of a particular variant: an insertion of about 3,000 extra DNA building blocks in the FKTN gene. This insertion reduces the amount of functional fukutin produced. A shortage of fukutin impacts the normal glycosylation of alpha-dystroglycan, leading to muscle fiber damage and brain abnormalities such as cobblestone lissencephaly.

Limb-girdle muscular dystrophy

MedlinePlus Genetics provides information about Limb-girdle muscular dystrophy.

Walker-Warburg syndrome

Variants in the FKTN gene can also cause Walker-Warburg syndrome, a severe form of congenital muscular dystrophy. The eye and brain abnormalities seen in those with Walker-Warburg syndrome are often more severe than those seen in people with Fukuyama congenital muscular dystrophy. The FKTN gene variants associated with this condition prevent the production of functional fukutin protein.

Other disorders

Variants in the FKTN gene have also been associated with another congenital muscular dystrophy called muscular dystrophy-dystroglycanopathy, type B4 (MDDGB4). People with MDDGB4 typically have muscle weakness and delayed development of motor skills.

Other Names for This Gene

  • FCMD
  • LGMD2M

Frequently Asked Questions

Diagnosis typically involves a clinical assessment of symptoms, brain imaging (MRI) to identify characteristic brain malformations, and sometimes a muscle biopsy. Genetic testing for mutations in the FKTN gene is the definitive diagnostic tool. Given its higher prevalence in individuals of Japanese ancestry, genetic testing specifically looks for common mutations in this population, such as the approximately 3,000 extra DNA building blocks insertion, which is a hallmark of the condition.
There is no cure for Fukuyama congenital muscular dystrophy, so management focuses on supportive care to alleviate symptoms and improve quality of life. This includes physical and occupational therapy to maintain muscle function and prevent contractures, respiratory support, nutritional support (often with feeding tubes), and medication to manage seizures. Regular monitoring by a multidisciplinary team, including neurologists, pulmonologists, and orthopedists, is essential.
Fukuyama congenital muscular dystrophy typically presents in infancy with severe muscle weakness, often described as a "floppy baby" (hypotonia). Affected children experience significant developmental delays, struggling to achieve milestones like sitting or walking. They often develop contractures (joint stiffness) and may have seizures, intellectual disability, and eye abnormalities. Brain imaging usually reveals characteristic structural changes, such as cobblestone lissencephaly.
Fukuyama congenital muscular dystrophy is inherited in an autosomal recessive pattern. This means that a child must inherit two copies of the mutated FKTN gene (one from each parent) to develop the condition. Parents who each carry one copy of the mutated gene are typically healthy carriers. For carrier parents, there is a 25% chance with each pregnancy that their child will inherit two mutated copies and be affected, a 50% chance the child will be a carrier, and a 25% chance the child will inherit two normal copies of the gene. Genetic counseling is highly recommended for families to understand these risks.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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