Phenotypes Associated with This Genotype

Genotype
MGI:8354282

• Allelic Composition: Sgcg^em1Mcn/Sgcg^em1Mcn
• Genetic Background: D2.B6-Sgcg^em1Mcn

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

behavior/neurological

decreased grip strength ( J:285272 )

• average forelimb grip strength is decreased in 2- and 4-month-old mice

muscle

abnormal skeletal muscle fiber morphology ( J:285272 )

• a greater percentage of myofibers have increased internal myonuclei at both 2 and 4 months of age

decreased skeletal muscle fiber diameter ( J:285272 )

• average cross-sectional area of myofibers is reduced

increased variability of skeletal muscle fiber size ( J:285272 )

• gastrocnemius muscle shows a change in fiber type composition, with a reduction in the percentage of Type 2B fast glycolytic myofibers and a trend towards an increased percentage of mixed myofibers

decreased skeletal muscle mass ( J:285272 )

• mice exhibit a reduction in muscle mass

• however, body mass at 2 and 4 months of age is normal

skeletal muscle fibrosis ( J:285272 )

• extensive fibrotic remodeling is seen and hydroxyproline concentration is increased in multiple muscles (abdominal, gastrocnemius/soleus, diaphragm, triceps)

skeletal muscle necrosis ( J:285272 )

calcified muscle ( J:285272 )

• muscles exhibit calcification

dystrophic muscle ( J:285272 )

• muscles exhibit muscular dystrophy pathological features, showing increased immune infiltrate, fibrosis, necrosis, calcification, fiber size variability and internal nuclei, with histology more severe at 4 months than at 2 months of age

abnormal muscle physiology ( J:285272 )

• mice exhibit increased skeletal muscle leak as indicated by increased dye uptake in diaphragm, abdominal, quadriceps, gluteus/hamstring, triceps, heart, and gastrocnemius/soleus muscles at 2 and even greater increase at 4 months of age

myositis ( J:285272 )

• gastrocnemius muscle exhibits increased number of F4/80+ macrophages and Ly6+ monocyte/neutrophils

impaired skeletal muscle contractility ( J:285272 )

• maximum tetanic force of the tibialis anterior muscle is decreased in 4-month-old mice

• specific force (tetanic force normalized to muscle cross-sectional area) is reduced in 4-month-old mice

• however, percent fractional shortening of cardiac muscle is normal at 4 months of age

myopathy ( J:285272 )

• mice develop progressive myopathy hallmarked by muscle membrane leak and fibrotic replacement

cardiovascular system

cardiac fibrosis ( J:285272 )

• severe ventricular fibrosis at 4 months of age, however percent fractional shortening is normal

homeostasis/metabolism

increased circulating creatine kinase level ( J:285272 )

• serum creatine kinase levels are increased at 2 months of age and further increased at 4 months

immune system

myositis ( J:285272 )

• gastrocnemius muscle exhibits increased number of F4/80+ macrophages and Ly6+ monocyte/neutrophils

respiratory system

abnormal respiratory function ( J:285272 )

• plethysmography shows increase Penh values, indicating abnormal breathing; when Penh is normalized to body mass, mice trend towards increased values

• other plethysmography parameters including minute volume/body mass, peak inspiratory flow (PIF)/body mass, peak expiratory flow (PEF)/body mass, and pause are not different and time relaxation trends towards significance

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
autosomal recessive limb-girdle muscular dystrophy type 2C		DOID:0110277	OMIM:253700	J:285272