Phenotypes associated with this allele

• Allele Symbol: Nrcam²⁰⁸⁸⁴
• Allele Name: 20884
• Allele ID: MGI:4361555
• Summary: 3 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Nrcam^20884/Nrcam^20884	involves: C57BL/6J	MGI:4361558
cx2	Lpin1^fld/Lpin1^fld Nrcam^20884/Nrcam^20884	involves: BALB/cByJ * C57BL/6J	MGI:4361560
cx3	Lpin1^20884/Lpin1^20884 Nrcam^20884/Nrcam^20884	involves: C57BL/6J	MGI:4361556

Genotype
MGI:4361558

hm1

• Allelic Composition: Nrcam²⁰⁸⁸⁴/Nrcam²⁰⁸⁸⁴
• Genetic Background: involves: C57BL/6J

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

behavior/neurological

decreased grip strength ( J:153042 )

• inconsistently significant weakness is detected in the forepaws starting a 14 weeks of age

• however, hindpaw grip strength is normal

nervous system

nervous system phenotype ( J:153042 )

N • unlike Nrcam²⁰⁸⁸⁴ Lpin1²⁰⁸⁸⁴ double homozygotes no defects in nerve morphology are detected

decreased nerve conduction velocity ( J:153042 )

• by 8 weeks of age conduction velocity is reduced in the sciatic nerve and the sural nerve

• decrease is less than in Nrcam²⁰⁸⁸⁴ Lpin1²⁰⁸⁸⁴ double homozygotes

• by 12 weeks of age nerve conduction in the sciatic nerve but not the sural nerve is similar to wild-type controls

Genotype
MGI:4361560

cx2

• Allelic Composition: Lpin1^fld/Lpin1^fld; Nrcam²⁰⁸⁸⁴/Nrcam²⁰⁸⁸⁴
• Genetic Background: involves: BALB/cByJ * C57BL/6J

behavior/neurological

hindlimb paralysis ( J:153042 )

• hindlimbs become fully paralyzed, although some hip function may be retained

forelimb paresis ( J:153042 )

• forelimbs show partial loss of function

muscle

skeletal muscle fiber atrophy ( J:153042 )

• develop severe muscle wasting by 2.5 weeks of age

growth/size/body

postnatal growth retardation ( J:153042 )

• seen by 2.5 weeks of age

• double mutants are considerably smaller than Lpin1 single homozygous littermates

Genotype
MGI:4361556

cx3

• Allelic Composition: Lpin1²⁰⁸⁸⁴/Lpin1²⁰⁸⁸⁴; Nrcam²⁰⁸⁸⁴/Nrcam²⁰⁸⁸⁴
• Genetic Background: involves: C57BL/6J

behavior/neurological

limb grasping ( J:153042 )

• hindlimb grasping

decreased grip strength ( J:153042 )

• at 4 weeks of age hindlimb grip strength is significantly reduced

• at 6 weeks of age half of the mice are unable to grip with their hindpaws

• by 8 weeks of age all of the mice are unable to grip with their hindpaws

• between 32 and 48 weeks of age all mice regain the ability to grip with their hindpaws

• reduced forelimb grip strength is seen at 6 weeks of age, weakness attenuates starting around 24 weeks of age

abnormal gait ( J:153042 )

• develop a floppy gait by 5 weeks of age

hindlimb paralysis ( J:153042 )

• develop hindlimb paralysis by 6 to 7 weeks of age

• paralysis is characterized by partial to total loss of hindlimb joint mobility, inability to grip with the hind paws, and hindlimb grasping when suspended by the tail

• paralysis phenotype attenuates over time

• after 14 weeks of age hindlimbs take on a flaccid disposition and progressively regain mobility and strength

• between 8 months and 1 year of age mice regain the ability to grip structures and walk although the gait remains floppy

paresis ( J:153042 )

• develop hindlimb paralysis by 6 to 7 weeks of age

• paralysis is characterized by partial to total loss of hindlimb joint mobility, inability to grip with the hind paws, and hindlimb grasping when suspended by the tail

abnormal nursing ( J:153042 )

♀ • appear to be incapable of suckling pups

abnormal sexual interaction ( J:153042 )

♂ • males do not breed

nervous system

abnormal myelin sheath morphology ( J:153042 )

• at 12 weeks of age some axons in the sciatic nerve have thin myelin sheaths

• at 12 weeks of age compact myelin structures are seen beside axons within Schwann cells

• at 52 weeks of age some axons with thin myelin sheaths are still present but the overall state of myelination has improved

abnormal sciatic nerve morphology ( J:153042 )

• at 8 weeks of age demyelinated axons are present and darkly stained debris is seen in the sciatic nerve

• appear less well organized compared to controls

demyelination ( J:153042 )

• at 8 and 12 weeks of age demyelinated axons are present in the sciatic nerve

• at 52 weeks of age some demyelinated axons are still present but the overall state of myelination has improved

• demyelination peaks at 8 weeks of age

abnormal action potential ( J:153042 )

• compound muscle action potentials are reduced at 8 and 12 weeks of age in the sciatic nerve and the sural nerve

decreased nerve conduction velocity ( J:153042 )

• at 4 and 8 weeks of age conduction velocity is reduced in the sciatic nerve and the sural nerve

muscle

skeletal muscle fiber atrophy ( J:153042 )

• widespread atrophic fibers are seen in the hindquarters of mice with hindlimb paralysis

skeleton

decreased joint mobility ( J:153042 )

• at the onset of paralysis joints appear stiff and are restricted to a bent position

growth/size/body

decreased body weight ( J:153042 )

• associated with onset of paralysis and muscle wasting

• body weight recovers in association with attenuation of paralysis and muscle wasting