If failure also happens during meiosis in these germ cells as they give rise to gametes, other XXXXY, XXXY and XXYY genotypes that also lead to Klinefelter syndrome can result including the rare situation where there's an additional Y chromosome.

如果有丝分裂和减数分裂均发生了不分离，那么这类Klinefelter综合征患者的基因型就可能是XXXXY，XXXY和XXYY等，包括了同时多出一条Y染色体的罕见情况。