Phenotypes associated with this allele

• Allele Symbol: Scyl1^mdf
• Allele Name: muscle deficient
• Allele ID: MGI:1856952
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Scyl1^mdf/Scyl1^mdf	B6C3Fe a/a-Scyl1^mdf/J	MGI:3712360
hm2	Scyl1^mdf/Scyl1^mdf	involves: CFW * C57BL/6J * C57BR	MGI:3712361

Genotype
MGI:3712360

hm1

• Allelic Composition: Scyl1^mdf/Scyl1^mdf
• Genetic Background: B6C3Fe a/a-Scyl1^mdf/J

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

nervous system

abnormal cerebellum morphology ( J:121817 )

abnormal Purkinje cell morphology ( J:121817 )

• axonal swelling reduced

abnormal Purkinje cell dendrite morphology ( J:121817 )

• dendritic arborization and ramification reduced

decreased Purkinje cell number ( J:121817 )

• overall reduction in number becoming very pronounced by 45 days of age

abnormal cerebellum vermis morphology ( J:121817 )

• marked atrophy of the cerebellar vermis

abnormal innervation ( J:30384 )

abnormal innervation pattern to muscle ( J:30384 )

• collateral reinnervation sometimes occurs and has a reticulated appearance

motor neuron degeneration ( J:30384 )

• vacuolation of motor neurons in the spinal cord and brain stem

• vacuolated cells in the spinal cord found exclusively in the ventral horn

• degenerating fibers often found in proximity to normal fibers

abnormal axon morphology ( J:121817 )

• axonal degeneration and loss of axons

• fewer myelinated fibers in the sciatic nerve and no large myelinated fibers

abnormal myelin sheath morphology ( J:30384 , J:121817 )

• fragmentation of myelin sheaths (J:30384)

• hypomyelination (J:121817)

abnormal neuromuscular synapse morphology ( J:30384 )

• motor nerve terminals are disorganized in shape

abnormal optic nerve morphology ( J:121817 )

• visibly smaller in cross section

• increase of small diameter myelinated fibers

• thinner myelinated sheaths

abnormal motor nerve collateral sprouting ( J:30384 )

• axonal sprouting

behavior/neurological

decreased grip strength ( J:30384 )

• progressive reduction of forelimb grip strength

abnormal stationary movement ( J:30384 )

abnormal tail movements ( J:30384 )

• loss of tail mobility over time

hindlimb paralysis ( J:30384 )

• hind-limbs are paralytic at 3 months of age but flexion of hindlimb digits is still possible

muscle

skeletal muscle fiber necrosis ( J:30384 )

• isolated necrotic fibers found in most muscles

muscular atrophy ( J:30384 )

• quadriceps femoris becomes atrophied sometimes involving entire muscle fascicles

• triceps brachii usually severely atrophied sometimes involving entire muscle fascicles

• extent of atrophy varies in different muscles and individuals

• some muscles are usually spared

abnormal muscle electrophysiology ( J:30384 )

• abnormal spontaneous electromyographic activity

• amplitude of muscle action potential about 1/3 of controls

abnormal muscle regeneration ( J:30384 )

• isolated regenerating fibers found in most muscles

skeleton

abnormal pelvic girdle bone morphology ( J:30384 )

• dorso-ventral flattening of the pelvis by 3 months of age

vision/eye

abnormal optic nerve morphology ( J:121817 )

• visibly smaller in cross section

• increase of small diameter myelinated fibers

• thinner myelinated sheaths

cellular

skeletal muscle fiber necrosis ( J:30384 )

• isolated necrotic fibers found in most muscles

Mouse Models of Human Disease		DO ID	OMIM ID(s)	Ref(s)
hereditary ataxia		DOID:0050951		J:121817

Genotype
MGI:3712361

hm2

• Allelic Composition: Scyl1^mdf/Scyl1^mdf
• Genetic Background: involves: CFW * C57BL/6J * C57BR

growth/size/body

decreased body size ( J:4479 )

• slightly smaller than controls at 5-6 weeks of age

reproductive system

reduced fertility ( J:4479 )

• fertility is low in affected individuals

behavior/neurological

abnormal involuntary movement ( J:4479 )

• fail to fully extend their hind limbs when lifted by the tail

tremors ( J:4479 )

• exhibit nervous tremors

abnormal locomotor behavior ( J:4479 )

• movement solely using forelimbs after 12 weeks when the hind limbs are dorsally contracted

abnormal gait ( J:4479 )

• waddling walk at 5-6 weeks of age

muscle

decreased skeletal muscle mass ( J:28676 )

• marked reduction in mass of hind limb muscles (sartorius, vasus lateralis, rectus femoris)

• forelimb muscle reduction more modest than in hind limbs

muscular atrophy ( J:4479 , J:28676 )

• atrophy of both type 1 and type 2 fibers (J:4479)

• secondary to chronic peripheral neuropathy (J:28676)

nervous system

abnormal somatic nervous system morphology ( J:28676 )

• chronic peripheral neuropathy

peripheral nervous system degeneration ( J:4479 )

• grouping of nerve fibers indicative of denervation and reinnervation

abnormal nervous system physiology ( J:4479 )

abnormal peripheral nervous system regeneration ( J:4479 )

• grouping of nerve fibers indicative of denervation and reinnervation