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Phenotypes Associated with This Genotype
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Lama2dy-7J mutation (1 available); any Lama2 mutation (107 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
• unlike other Lama2 mutants, mice exhibit a normal lifespan

• axial, limb, fast-fiber-composed and slow fiber-composed muscles contain myofibers of different calibers separated by monocyte-rich endomysial connective tissue unlike in wild-type mice
• at 8 weeks of age, mice exhibit signs of muscular dystrophy including widespread endomysial fibrosis
• at 8 weeks of age, mice exhibit signs of muscular dystrophy including widespread endomysial fibrosis, focal necrosis and central nuclei typical in regenerated fibers
• at 7 to 8 weeks of age, myofibers contain many centrally located nuclei indicating regeneration of fibers
• mice retain a higher regenerative capacity than Lama2dy homozygotes but exhibit an increase in centrally located nuclei compared to controls
• beginning at about 2-6 weeks of age, mutant mice exhibit spasms of the hindlimbs that extend the limbs backward or contract them close to the body
• pathological examination of a 110 day old mutant mouse revealed signs of myopathy (J:82238)
• 4 of 21 mice exhibit progressive skeletal muscle wasting at juvenile ages and bilateral contracture of the hindlimbs by 12 weeks of age (J:134367)
• muscle pathology is similar to in Lama2dy-2J homozygotes but less severe than in Lama2dy homozygotes (J:134367)

• upon being picked up by the tail, beginning around 2-6 weeks of age, a mutant mouse either extends its rear legs backward or contracts them close to the body
• by 6 weeks of age, mice exhibit partial paralysis of hindlimbs with some hindlimb function retained at 8 to 10 months of age
• paralysis of hindlimbs is less severe than in Lama2dy-2J homozygotes

nervous system
• peripheral nerve roots in the spine exhibit severe hypomyelination
• immature Shwann cells adher lossely to axons and do not extend processes into bundles unlike in wild-type mice
• mice exhibit a consistent defect in myelination compared to Lama2dy-2J homozygotes that exhibit a variable hypo-myelination phenotype
• most axons roots lack ensheathing processes of Schwann cells
• pathological examination of a 110 day old mutant mouse identified unmyelinated peripheral nerve fibers

• after 5 weeks of age

• contrary to in other Lama2 mutants, the basal lamina is thicker than in wild-type mice
• the basal lamina was absent from non- and pre-myelinating Schwann cells

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
congenital merosin-deficient muscular dystrophy 1A DOID:0110636 OMIM:607855

Contributing Projects:
Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Models of Human Cancer database (MMHCdb) (formerly Mouse Tumor Biology (MTB)), Gene Ontology (GO)
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last database update
MGI 6.22
The Jackson Laboratory