Rather than having the normal 46 chromosomes, okapi more commonly have 45 or 44 chromosomes, a number that’s usually abnormal or fatal for other animals.
Because of their unusual chromosome numbers, okapis have been the subject of considerable genetic interest.
Chromosome research has revealed that okapi individuals having 45 chromosomes, (2n=45,) were more common than those having the expected 46 chromosomes, (2n=46.) Okapi can even have 44 chromosomes, (2n=44.) In other animals, such variations are abnormal or fatal. Okapis with such numbers, however, are otherwise normal.
This anomaly has been related to the Robertsian fusion phenomenon.