According to Wikipedia:
HOTAIR (for HOX antisense intergenic RNA) is a human gene located on chromosome 12. It is the first example of an RNA expressed on one chromosome that has been found to influence transcription on another chromosome.
However, Wikipedia itself cites Genecards, which has a slightly different metanym expansion (without any missing letters) for HOTAIR: HOX Transcript Antisense RNA. Either way, a very interesting gene and, though ad hoc intranym, certainly contrived enough for ORCA!
(HOTAIR possibly needs a new ORCA classification because both “metanym” sub-acronyms - HOX (Homeobox) and RNA (Ribonucleic acid) are themselves “itranyms”, as is HOTAIR.)