Limb-girdle muscular dystrophy

Limb-girdle muscular dystrophy
Classification and external resources
ICD-10	G71.0
ICD-9	359.1
DiseasesDB	32189
eMedicine	neuro/189
MeSH	D049288

Limb-girdle muscular dystrophy or Erb's muscular dystrophy is an autosomal class of muscular dystrophy that is similar but distinct from Duchenne muscular dystrophy and Becker's muscular dystrophy. Limb-girdle muscular dystrophy encompasses a large number of rare disorders.

Presentation

The term "limb-girdle" is used to describe these disorders because the muscles most severely affected are generally those of the hips and shoulders -- the limb girdle muscles.

Common symptoms of limb-girdle muscular dystrophy are muscle weakness, myoglobinuria, pain, myotonia, cardiomyopathy, elevated serum CK, and rippling muscles.

The muscle weakness is generally symmetric, proximal, and slowly progressive.

In most cases, pain is not present with LGMD, and mental function is not affected.

LGMD can begin in childhood, adolescence, young adulthood or even later. The age of onset is usually between 10 and 30. Both genders are affected equally. When limb-girdle muscular dystrophy begins in childhood the progression appears to be faster and the disease more disabling. When the disorder begins in adolescence or adulthood the disease is generally not as severe and progresses more slowly.

There is no sensory neuropathy or autonomic or visceral disfunction at presentation.the specific dermatomes affected can be demonstrated clinically,and although lower limb deep tendon reflexes and plantar reflex are lost, abdominal reflexes are preserved

Prognosis

The distal muscles are affected late in LGMD, if at all. Over time (usually many years), the person with LGMD loses muscle bulk and strength. Eventually, s/he may need a power wheelchair or scooter, especially for long distances. The various forms of LGMD are highly variable, and can be variable even among persons with the same form of LGMD. In its most severe form, LGMD2C, the symptoms are usually similar to Duchenne Muscular Dystrophy, with individuals losing the ability to walk between ages 10 and 12.

While LGMD isn't typically a fatal disease, it may eventually weaken the heart and respiratory muscles, leading to illness or death due to secondary disorders. In its most severe form, LGMD2C, lifespans are typically limited to the 20s or early 30s.

Diagnosis

A person need to perform "Muscle biopsy" test in order to know whether he has muscular dystrophy or not , "Genetic testing" need to be done in order to find the type of LGMD

Currently a "CHIP" is being developed by an organization called "NMD CHIP"

The project is designing chips for the diagnosis of mutations already known to cause Duchenne / Becker muscular dystrophies (DMD/BMD), limb girdle muscular dystrophies (LGMD), congenital muscular dystrophies (CMD), and hereditary motor-sensory neuropathies or Charcot-Marie-Tooth neuropathies (CMT). These diagnostic chips are described as "known-gene chips".

A project website has been set up at www.nmd-chip.eu which enables dissemination of information about the project to stakeholders.

Genetics

LGMD is typically an inherited disorder, though it may be inherited as a dominant, recessive, or X-linked genetic defect. The result of the defect is that the muscles cannot properly form the proteins needed for normal muscle function. Several different proteins can be affected, and the specific protein that is absent or defective identifies the specific type of muscular dystrophy. Among the proteins affected are α, β, γ and δ sarcoglycans. The sarcoglycanopathies could be possibly amenable to gene therapy.

Treatment

Treatment for LGMD is primarily supportive. Exercise and physical therapy are advised to maintain as much muscle strength and joint flexibility as possible. Calipers may be used to maintain mobility and quality of life. Careful attention to lung and heart health is also required. IVIg may increase strength in some forms and prevent progression in others, possibly through the prevention of fibrosis and inflammation without the secondary weakening caused by corticosteroids.

Research

There is currently not an effective treatment or cure to address the underlying genetic defects that cause LGMD. There is a variety of research underway targeted at various forms of LGMD. Methods thought to hold significant promise for an effective treatment include "exon skipping" and gene therapy. Several clinical trials are underway and seeking to apply these methodologies to various limb girdly dystrophies.

List of limb-girdle muscular dystrophies

The "LGMD1" family is autosomal dominant, and the "LGMD2" family is autosomal recessive.

Name	OMIM	Location
LGMD1A	159000	TTID
LGMD1B	159001	LMNA
LGMD1C	607801	CAV3
LGMD1D	603511	7q
LGMD1E	602067	6q23
LGMD1F	608423	7q32.1-q32.2
LGMD1G	609115	4q21
LGMD2A	253600	CAPN3
LGMD2B	253601	DYSF
LGMD2C	253700	SGCG
LGMD2D	608099	SGCA
LGMD2E	604286	SGCB
LGMD2F	601287	SGCD
LGMD2G	601954	TCAP
LGMD2H	254110	TRIM32
LGMD2I	607155	FKRP
LGMD2J	608807	TTN
LGMD2K	609308	POMT1
LGMD2L	611307	ANO5
LGMD2M	611588	FKTN
LGMD2N	607439	POMT2
LGMD2O	606822	POMGNT1

External links

• Muscular Dystrophy Association
• LGMD in MDA website
• GeneReviews/NCBI/NIH/UW entry on Limb-Girdle Muscular Dystrophy Overview
• GeneReviews/NCBI/NIH/UW entry on Calpainopathy
• GeneReviews/NCBI/NIH/UW entry on Dysferlinopathy including Miyoshi Distal Myopathy (Miyoshi Myopathy), Limb-Girdle Muscular Dystrophy Type 2B (LGMD2B)
• Healthline for Patients
• Washington University in St. Louis Neuromuscular Section LGMD
• Duke University (Great Clinical Description of LGMD phenotypes
• Glenn Lopate MD for emedicine
• Jain Foundation Inc:Orchestrating a cure for Miyoshi/LGMD2B
• Kurt+Peter Foundation: Raising funds for a cure for LGMD2C