Mouse Genome Informatics
ht
    Ryr1tm1.1Dhm/Ryr1+
involves: 129S2/SvPasCrl * 129S6/SvEvTac
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
       

Kyphosis, hindlimb paresis and myofiber abnormalities in Ryr1tm1.1Dhm/Ryr1+ mice

muscle
• myofibers undergo a transition from small, compacted areas resembling minicores in younger mice to nemaline-rod like inclusions in adults
• type 2 (fast) myofibers exhibit gross structural defects in myofibrillar organization; myofibrils vary greatly in thickness and there are numerous sites of splitting and thinning
• type 1 fiber hypotrophy/atrophy is detected in muscle fibers as early as 6 weeks of age
• core lesions show Z-line streaming and focal loss of a Z-disk
• spatial disruption of sarcomeric and myofibrillar arrangement of myofibers due to minicore/core lesions
• type 2 myofibrils exhibit sarcomeric shortening, insertion of an additional sarcomere, and loss of sarcomeric register
• skeletal muscle exhibits increased endomysial spacing and mild fibrosis
• mutant soleus fibers exhibit minicores (discrete foci of oxidative enzyme depletion) at 12 months of age; by 20 months of age, larger areas of oxidative enzyme depletion, consistent with cores, are seen in type 1 fibers
• intermyofibrillar spaces are reduced and mitochondria and sarcoplasmic reticulum are absent from core lesion areas
• at 18 months of age, type I and type 2 fibers have reduced diameters, suggesting general fiber atrophy
• fast-twitch and slow-twitch muscles exhibit a 28-34% lower force during a single twitch and submaximal titanic contractions at 2 months of age
• about 37% decrease in peak twitch force and maximal twitch rate of contraction in muscles
• mobility impairment is first seen as weakness of hind limbs at around 6 months of age
• heterozygotes exhibit slowly progressive congenital myopathy, however show no evidence of muscle wasting or skeletal muscle degeneration

respiratory system
• mutants start to breathe regularly 15-20 min after birth compared to 5-7 min for wild-type mice

skeleton
• heterozygotes develop dorsal kyphosis in the cervicothoracic region with age, most likely due to overuse of the forelimbs for locomotion

growth/size
• very low fat deposits
• average body weight is about 15% lower than in wild-type

behavior/neurological
• 80% of heterozygotes show varying degrees of motor dysfunction by 10 months of age
• by 12 months of age, 14% of mutants exhibit complete hind limb paralysis

homeostasis/metabolism
• mutants are flaccid and cyanotic during the first minutes after delivery

adipose tissue
• very low fat deposits

Mouse Models of Human Disease
OMIM IDRef(s)
Central Core Disease of Muscle 117000 J:155825
Minicore Myopathy with External Ophthalmoplegia 255320 J:155825