the hereditary goitre of afrikander cattle is an autosomal recessive disease characterized in homozygotes by the production of abnormal thyroglobulin ( tg ) and the coexistence in the thyroid of normal-sized 8.4-kilobase ( kb ) tg mrna with a misspliced 7.3-kb message having lost exon 9 .
C0018021
goitre
C0040132
thyroid