<prompt> XXY klinfilter which has extra?X-chromosomeY chromosomeBothNone  <response>: Ans. is a i.e., X-chromosome The major numerical disorders of chromosomes are 3 autosomal trisomies Trisomy 21 -- Down syndrome Trisomy 18 -- Edwards syndrome Trisomy 13 -- Patau syndrome Four types of sex chromosomal aneuploidies: Turner syndrome usually 45,X Klinefelter syndrome 47,XXY 47,XXX 47,XYY By far the most common type of trisomy in liveborn infants is trisomy 21 karyotype 47,,21 or 47,XY 21 or Down syndrome. 