Muscular Dystrophy, Congenital Merosin-Deficient, 1A

Alternative Names

  • MDC1A
  • Muscular Dystrophy, Congenital Merosin-Deficient
  • Muscular Dystrophy, Congenital, Due to Partial LAMA2 Deficiency

Associated Genes

Laminin, Alpha-2
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WHO-ICD-10 version:2010

Diseases of the nervous system

Diseases of myoneural junction and muscle

OMIM Number

607855

Mode of Inheritance

Autosomal recessive

Gene Map Locus

6q22-q23

Description

Congenital muscular dystrophy type 1A (MCD1A) is a rare disease, which is one of a group of neuromuscular disorders with onset at birth or infancy and distinguished through hypotonia, muscle weakness and muscle wasting. MCD1A stands for 30-40% of congenital muscular dystrophies with a prevalence of 1 in 30,000.

Since merosin deficiency can be identified in the muscle and skin, the disease is diagnosed through obtaining a muscular biopsy. Prenatal diagnosis can be performed at the ninth week through chorionic villus sampling for an indication of merosin deficiency and any mutations of LAMA2 gene.

Molecular Genetics

MCD1A occurs due to mutations of the LAMA2 gene which codes for the alpha-2 laminin chain.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
607855.1LebanonFemaleYes Muscular hypotonia; Motor delay; Abnor... NM_000426.3:c.8244+3_8246+6delAAGHomozygousAutosomal, RecessiveNair et al. 2018
607855.2Lebanon Muscular dystrophy; Mildly elevated cre... NM_000426.3:c.1300C>T, NM_000426.3:c.3829C>THeterozygousAutosomal, RecessiveNair et al. 2018

Other Reports

Kuwait

Abdulla et al. (2007) represented MRI results of two cases with merosin-negative congenital muscular dystrophy (CMD) to distinguish merosin-negative CMD amongst other CMD types. Case 1 represented a 3 year old girl suffering from hypotonia, neck and trunk weakness, poor weight gain, slow feeding, weak cry, head lag, and weak hand grasp. The girl was not able to sit or bear weight on her legs. Case 2 represented a 6 month old girl suffering from congenital hypotonia, proximal limb girdle weakness, myopathic facies and normal head circumference. Merosin-negative CMD was distinguished through the absence of brainstem involvement, polymicrogyria or cobblestone lissencephaly in both cases. Furthermore, Abdulla et al. (2007) confirmed the diagnosis through muscle biopsy which demonstrated dystrophic modifications.

Habeeb et al. (2006) described 21 Arab children with the pure type of congenital muscular dystrophy with normal mental status, except one case with perinatal hypoxic-ischemic insult. Fourteen were laminin alpha2 (merosin) deficient, and six were laminin alpha2 positive; laminin alpha2 status was not determined in one patient. None of the laminin alpha2-deficient patients achieved independent ambulation, whereas three of the laminin alpha2-positive patients were able to walk. Radiologic evaluation demonstrated an abnormal central white-matter signal in 11 of 13 laminin alpha2-deficient and in 1 of 5 laminin alpha2-positive patients; none had evidence of brain dysplasia. Nerve conduction velocities were normal in 5 of 5 laminin alpha2-positive patients, whereas in the laminin alpha2-deficient patients, it was slow in 9 of 11 for the motor nerves and normal in 8 of 9 for the sensory nerve. Two of the laminin alpha2-positive patients had pseudohypertrophy of the calves, and two of the laminin alpha2-deficient ones had seizures. The patient in whom the laminin alpha2 status was not determined had a severe course, an abnormal central white-matter signal, and epilepsy and resembled more the laminin alpha2-deficient group.

[See also: Kuwait > Al-Ajmi et al., 2001].

Syria

Al-Ajmi et al. (2001) described the first Syrian patient to be diagnosed with merosin deficient congenital muscular dystrophy. The patient was a 2-year old boy who presented at Al-Sabah Hospital in Kuwait suffering from congenital muscular dystrophy. MRI brain in his case showed extensive abnormalities of white matter. His EEG pattern was peculiar with fast rhythms in occipito-temporal regions.

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