Mouse Genome Informatics
hm
    Lrp5tm1Kry/Lrp5tm1Kry
either: (involves: 129S1/Sv * 129X1/SvJ) or (involves: 129S1/Sv * 129X1/SvJ * C57BL/6J)
Key:
phenotype observed in females WTSI Wellcome Trust Sanger Institute
phenotype observed in males EuPh Europhenome
N normal phenotype
       

Low bone mass in Lrp5tm1Kry/Lrp5tm1Kry mice

mortality/aging
• a small but significant number of mutants die within the first month, likely as a result of bone fractures

skeleton
N
• some homozygotes walk with noticeable limps, observed at 2 months of age, resulting from tibial fractures (J:75973)
• there is decreased bone volume compared to wild-type
• mutant have significantly decreased numbers in the primary and secondary spongiosa
• in calvaria, osteoblasts are reduced in number and show lower levels of proliferation (lower mitotic index)
• at 2 weeks of age, mice show decreased mineralized bone in the primary spongiosa
• all homozygotes have a low bone mass phenotype at 2 months of age in all animals regardless of sex and at all stages analyzed
• bone mass remains lower in mutants throughout life
• bone formation is abnormal, but bone resorption does not appear to be affected
• at E17.5 no defect in ossification is observed, but a subtle delay is seen in the digits of newborn mutants; fifth middle phalangeal ossification center is absent
• in 4-day old mutants delay is more pronounced, with absent or reduced ossification centers of the wrist, distal metacarpal bones, femora, humeri and ulnae
• in 6-month-old mice, a 2-fold decrease in bone formation rate (BFR) is observed; similar results are seen in 2- and 4-month-old animals
• this is due to decreased matrix apposition rate (MAR - amount of bone matrix deposited per osteoblast cluster; 0.75 um/day vs 0.45 um/day in wild-type); similar results are seen in 2- and 4-month-old animals

vision/eye
• in 70% of 6-month old mutants hyaloid vessels are present in the eyes; regression of capillary networks is delayed in mutants analyzed between P3-P8 compared to wild-type and heterozygotes

cellular
• mutants show lower levels of macrophage-mediated apoptosis in hyaloid vessel segments of the eye at all time points, compared to wild-type

Mouse Models of Human Disease
OMIM IDRef(s)
Osteoporosis-Pseudoglioma Syndrome; OPPG 259770 J:75973