Limb-girdle muscular dystrophy type 2I

Alternate names

Autosomal recessive limb-girdle muscular dystrophy type 2I; LGMD2I; Limb-girdle muscular dystrophy due to FKRP deficiency; Muscular dystrophy-dystroglycanopathy (limb-girdle), type C, 5 ; FKRP-related limb-girdle muscular dystrophy R9; FKRP-related LGMD R9; LGMD due to FKRP deficiency; LGMD type 2I

Definition

Limb-girdle muscular dystrophy type 2I (LGMD2I) is a form of limb-girdle muscular dystrophy, which refers to a group of conditions that cause weakness and wasting of the muscles in the arms and legs. The proximal muscles (those closest to the body such as the upper arms and thighs) are generally most affected by the condition.

Epidemiology

It is difficult to determine the prevalence of limb-girdle muscular dystrophy because its features vary and overlap with those of other muscle disorders. Prevalence estimates range from 1 in 14,500 to 1 in 123,000 individuals.

Cause

LGMD2I is caused by changes (mutations) in the FKRP gene.

Inheritance

Autosomal recessive inheritance, a 25% chance

It is inherited in an autosomal recessive manner.

Onset

In LGMD2I, specifically, signs and symptoms often develop in late childhood (average age 11.5 years) and may include difficulty running and walking. The symptoms gradually worsen overtime and affected people generally rely on a wheelchair for mobility approximately 23-26 years after onset.

Signs and symptoms

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Elevated serum creatine kinase(Elevated blood creatine phosphokinase)
• Muscular dystrophy
• Proximal muscle weakness(Weakness in muscles of upper arms and upper legs)
• Reduced muscle fiber alpha dystroglycan

30%-79% of people have these symptoms

• Abnormality of the Achilles tendon
• Calf muscle hypertrophy(Increased size of calf muscles)
• Generalized hypotonia(Decreased muscle tone)
• Pelvic girdle muscle weakness
• Shoulder girdle muscle weakness(Weak shoulder muscles)
• Waddling gait('Waddling' gait)

5%-29% of people have these symptoms

• Difficulty climbing stairs(Difficulty walking up stairs)
• Difficulty running
• Dilated cardiomyopathy(Stretched and thinned heart muscle)
• Frequent falls
• Motor delay
• Reduced muscle fiber merosin
• Scoliosis

1%-4% of people have these symptoms

• Exercise-induced myoglobinuria

Diagnosis

Molecular Genetics Tests

• Targeted variant analysis
• Deletion/duplication analysis
• Sequence analysis of select exons
• Sequence analysis of the entire coding region

Treatment

There is, unfortunately, no cure for LGMD2I and treatment is based on the signs and symptoms present in each person.

NIH genetic and rare disease info

• NIH info on Limb-girdle muscular dystrophy type 2I

Limb-girdle muscular dystrophy type 2I is a rare disease.