Triploidy. Karyotype (set of chromosomes) of a person with triploidy, trios of each chromosome rather than pairs. Most humans have 46 chromosomes in 23 pairs - in the case of triploidy they have 69 chromosomes. The sex chromosomes are seen at centre and lower right: one Y chromosome and two X chromosomes. Triploidy is extremely rare, and affected foetuses are usually miscarried. The condition causes wide-ranging and serious deformities, and even if they survive to birth they generally live no more than a few months.