Where Did the Aneuploidy Come from?

Most Aneuploidies Arise from Errors in Meiosis, Especially in Maternal Meiosis I. For some time, researchers have known that most aneuploidies result from the nondisjunction of chromosomes during meiosis.

How aneuploidy is formed?

Errors in chromosome segregation lead to aneuploidy, a state where the number of chromosomes in a cell or organism deviates from multiples of the haploid genome. Aneuploidy arising through chromosome mis-segregation during meiosis is a major cause of infertility and inherited birth defects.

What is the main cause of aneuploidy during meiosis?

Disorders of chromosome number are caused by nondisjunction, which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis I or II (or during mitosis).