Mouse Genome Informatics
hm1
    Lama2dy-7J/Lama2dy-7J
C57BL/6J-Lama2dy-7J/J
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
mortality/aging
N
• unlike other Lama2 mutants, mice exhibit a normal lifespan (J:134367)

muscle
• 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)

behavior/neurological
• 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
• by 6 weeks of age, mice exhibit partial paralysis of hindlimbs with some hindlimb function retained at 8 to 10 months of age

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

growth/size/body
• after 5 weeks of age

cellular
• 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