The absence of mutations in homeobox candidate genes HOXA3, HOXB3, HOXD3 and PITX2 in familial and sporadic thyroid hemiagenesis.

BACKGROUND:The molecular mechanisms leading to the formation of the two thyroid symmetrical lobes, which are impaired in thyroid hemiagenesis (TH), are little known. OBJECTIVE:The aim of this work was to search for mutations in thyroid developmental candidate genes HOXA3, HOXB3, HOXD3 and PITX2. METHODS:Total DNA from peripheral blood was extracted and then the entire coding region of all these genes was amplified by polymerase chain reaction and direct sequencing. RESULTS:Herein we describe familial cases of TH in two generations (proband and his father), in addition to other two sporadic cases. We have found polymorphisms in the HOXB3 (rs2229304), HOXD3 (rs34729309, rs1051929, c.543-199G>T and c.543-34G>A; and a new synonymous variant, NP_008829.3:p.314;C>G) and PITX2 (c.45+76C>T) genes, but no deleterious mutations. CONCLUSION:These results suggest the existence of other left-right thyroid asymmetry candidate genes in humans such as classical Mendelian mutation-causing disease, as well as other etiopathogenic mechanisms such as epigenetic modifications, especially for sporadic hemiagenesis.

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