TN 3 (02-10)
DI 23022.450 Merosin Deficient Congenital Muscular Dystrophy
MEROSIN DEFICIENT CONGENITAL MUSCULAR DYSTROPHY
Merosin Deficient CMD; Laminin alpha-2; LAMA2; Muscular Dystrophy Congenital; Merosin Positive CMD; LAMM; MDCMD; Congenital Muscular Dystrophy with laminin-alpha-2 deficiency; MDC1A; Classic CMD LAMA2
Merosin Deficient Congenital Muscular Dystrophy (CMD) is rare and one of the most severe types of muscular dystrophy. Laminin alpha-2 is a protein that in humans is encoded by the LAMA2 gene. Mutations in this gene have been identified as the cause of congenital merosin-deficient CMD. Children with this form of CMD lack all or part of the muscle protein merosin, or laminin. Parents first notice this condition when a child fails to ambulate due to weakness and contractures and has breathing problems which could need tracheotomy. Most infants have normal intelligence but some have been reported to show intellectual disability and epilepsy. The severity of this condition is determined by the amount of the merosin protein that the child has.
TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
Diagnostic Testing: MRI of the brain, Serum creatine kinase (CK) concentration, muscle biopsy, immunostaining of muscle, and genetic testing.
ICD-9: 359.0 Congenital hereditary muscular dystrophy
ONSET AND PROGRESSION
The physical characteristics of Meronsin Deficient CMD are slowly progressive leading to muscle weakness and wasting.
There is currently no cure for Merosin Deficient CMD. The conditions of life are improved by physiotherapy to reduce contracture and arthrodesis to limit deformation. Ventilatory support and tracheotomy, when necessary, have contributed to a marked increase of the life expectancy for the most severely affected patients.
SUGGESTED PROGRAMMATIC ASSESSMENT*
Suggested MER for Evaluation: Clinical examination including a description of physical findings, family history, genetic testing, electromyography or nerve conduction tests, and blood and enzyme tests.
Suggested Listings for Evaluation:
Merosin Deficient CMD produces long term interference with age appropriate activities resulting in extreme limitations of functioning.
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or Listings suggested to evaluate the claim. However, the decision to allow or deny the claim rests with the adjudicator.