Phenotypes Associated with This Genotype

Genotype
MGI:3700828

• Allelic Composition: Thra^tm2Ven/Thra^tm2Ven; Thrb^tm1Df/Thrb^tm1Df
• Genetic Background: involves: 129P2/OlaHsd * BALB/c * C57BL/6J

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

growth/size/body

postnatal growth retardation ( J:118402 )

• double homozygotes exhibit a retarded weight gain over the first 5 postnatal weeks, but only to the same extent as in single Thra^tm2Ven homozygotes

• no significant difference in postnatal weight gain is noted after 5 weeks

endocrine/exocrine glands

abnormal thyroid follicle morphology ( J:118402 )

• similar to Thra^tm2Ven mice, double homozygotes show thyroid follicles with a somewhat thin, flattened epithelium, but lack the enlargement observed in single Thrb^tm1Df homozygotes

homeostasis/metabolism

abnormal thyroid hormone level ( J:118402 )

• similar to Thra^tm2Ven mice, double homozygotes display normal TSH and slightly low T4 and T3 levels, indicating dominant suppression of the hormonal disorder observed in single Thrb^tm1Df homozygotes

decreased circulating thyroxine level ( J:118402 )

• similar to Thra^tm2Ven mice, double homozygotes display serum free T4 levels that are slightly but significantly below wild-type levels

decreased circulating triiodothyronine level ( J:118402 )

• similar to Thra^tm2Ven mice, double homozygotes display free T3 levels that are slightly but significantly below wild-type levels; total T3 is also slightly lowered

hearing/vestibular/ear

hearing/vestibular/ear phenotype ( J:118402 )

N • at 7-17 weeks of age, double homozygotes display normal ABR thresholds in response to click or pure-tone (8, 16, 32 kHz) stimuli, indicating suppression of the auditory defect observed in single Thrb^tm1Df homozygotes

N • Background Sensitivity: on a mixed genetic background of equal parts 129/Sv, 129OlaHsd, BALB/c, and C57BL/6J strains, ABR responses are similar but more variable than those observed on a congenic C57BL/6J background

N • consistent with rescued ABR thresholds, the developmental expression of the I_K,f potassium current in cochlear IHCs is also largely corrected at P30 relative to single Thrb^tm1Df homozygotes