Aneuploidy refers to the condition in which an abnormal number of chromosomes is present within a  cell (either 46 0r 47 chromosomes instead of the normal 46 chromosomes). An allosome is a chromosome that is different from the rest of the chromosomes (autosomes) in its size and structure (X and Y chromosomes). In hyperdiploidy, the number of chromosomes is higher than the normal (46) which is caused due to the disjunction at the time of meiosis and results in trisomy, etc. of a chromosome. In an allosomal hyperneuploid disorder, there is an increase in the number of either the X chromosome or the Y chromosome.  For example, in Klinefelter’s syndrome, the karyotype of an individual is 44+XXY as an extra X chromosome is present in the male.  Some common characters of this syndrome include infertility, high-pitched voice, gynecomastia, small-sized testicles, language and learning difficulties, etc.