Mouse Genome Informatics
involves: 129P2/OlaHsd * 129S1/SvImJ * C57BL/6J
phenotype observed in females
phenotype observed in males
N normal phenotype
• intercrosses of heterozygotes yields only 16% homozygotes, less than mendelian prediction, indicating in utero loss

hematopoietic system
• the white blood cell count is normal
• spleens are normal in weight and iron content
• red blood cells are osmotically fragile, shperocytic, hypochromic, microcytic, and have a lower maximum deformability index with ektacytometry showing a loss of membrane surface area
• more pronounced in males than females
• in both males and females
• red blood cells have diminished membrane surface area relative to that in wildtype controls
• platelet counts are elevated significantly in males and to a lesser extent in females
• mean platelet volume is significantly lower in females and lower in males to a level that did not reach statistical significance
• found in both males and females
• indicative of a compensatory increase in the rate of erythropoiesis

• platelet shape and bleed time are normal
• plasma BUN and electrolyte concentrations are normal

nervous system
• approximately half of homozygotes develop hydrocephaly, and on average this phenotype is overtly visible by 8 weeks of age
• progressive dilation of the lateral and third ventricles with the cerebral aqueduct open resulting in accumulation of fluid within the fourth ventricle

• homozygotes are smaller than normal at birth and throughout life
• average weight of only approximately 10g at 5 weeks of age is much less than littermate controls