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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID
Map1b+
wild type
MGI:2436787
Summary 2 genotypes
Jump to Allelic Composition Genetic Background Genotype ID
ht1
Map1btm1Rak/Map1b+ involves: 129P2/OlaHsd * C57BL/6J MGI:3848514
cx2
Kif21atm1.1Ece/Kif21a+
Map1btm1Prop/Map1b+
Tg(Isl1-EGFP*)1Slp/0
involves: 129S1/Sv * 129S4/SvJae * 129X1/SvJ * BALB/c * C57BL/6 MGI:6241441


Genotype
MGI:3848514
ht1
Allelic
Composition
Map1btm1Rak/Map1b+
Genetic
Background
involves: 129P2/OlaHsd * C57BL/6J
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Map1btm1Rak mutation (0 available); any Map1b mutation (85 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
mortality/aging
• mice that develop hindlimb paralysis due to starvation and dehydration

behavior/neurological
• in mice with defects in both ocular orbs
• mice with defects in both ocular orbs exhibit severe spastic tremors in the hindlimbs
• mice with defects in both ocular orbs exhibit an ataxic gait
• mice with defects in both ocular orbs exhibit an ataxic gait
• in some mice

nervous system
• the hippocampus lacks 6D4 staining
• some mice exhibit abnormal cerebellum shape and size with an attenuated, flattened cerebellar hemisphere and vermis compared with wild-type mice
• Purkinje cells lose their flask-shaped appearance and appear flattened
• Purkinje cells are attenuated with truncated dendritic processes and decreased branching compared with wild-type cells

vision/eye
• 20% of mice exhibit gross deformities of the one or both ocular orbs compared with wild-type mice
• eyes are underdeveloped
• the demarcation of the external plexiform layer are absent
• mice with defects in both ocular orbs fail to respond to visual threats

growth/size/body
• at 5 months of age
• mice weight 10-50% less than controls

limbs/digits/tail
• at 5 months, mice exhibit splayed hindlimbs unlike wild-type mice




Genotype
MGI:6241441
cx2
Allelic
Composition
Kif21atm1.1Ece/Kif21a+
Map1btm1Prop/Map1b+
Tg(Isl1-EGFP*)1Slp/0
Genetic
Background
involves: 129S1/Sv * 129S4/SvJae * 129X1/SvJ * BALB/c * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Kif21atm1.1Ece mutation (0 available); any Kif21a mutation (80 available)
Map1btm1Prop mutation (0 available); any Map1b mutation (85 available)
Tg(Isl1-EGFP*)1Slp mutation (1 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
nervous system
• approximately 90% penetrance of abducens nerve hypoplasia
• oculomotor nerve superior branch axons terminate prematurely within a bulb with a penetrance of 90%





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Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Models of Human Cancer database (MMHCdb) (formerly Mouse Tumor Biology (MTB)), Gene Ontology (GO)
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last database update
12/30/2025
MGI 6.24
The Jackson Laboratory