Question
Does chromosome 22 duplication affect fertility and child development?
Answer
Chromosomes are carriers of genes, and chromosomal disorders result in abnormal gene expression and developmental abnormalities. The pathogenesis of chromosomal anomalies is not clear; they may result from the failure of chromosomes to separate properly during cell division or from breaks and rejoining of chromosomes in response to various internal and external factors. 1. Physical factors: Human exposure to radiation environments, including natural and artificial radiation. Natural radiation includes cosmic radiation, terrestrial radiation, and radioactive substances within the human body, while artificial radiation includes medical radiation and occupational exposure. Ionizing radiation is particularly noteworthy because it can cause non-disjunction of chromosomes. Experiments have shown that comparing metaphase II oocytes from irradiated mice with those from non-irradiated mice of the same stage, there was a significant increase in non-disjunction in the irradiated group, especially in older mice. Lymphocytes exposed to radiation or grown in irradiated sera showed a higher frequency of trisomy in the experimental group, leading to translocations, deletions, and other chromosome abnormalities. 2. Chemical factors: People are exposed to a variety of chemicals in daily life, some of which are naturally occurring and others synthetic. These chemicals can enter the body through diet, breathing, or skin contact, leading to chromosome abnormalities. 3. Biological factors: When viruses are used to treat cells in culture, a variety of chromosome abnormalities often occur, including breaks, fragmentation, and translocations. 4. Age effect of the mother: By the sixth or seventh month of pregnancy, all oogonia have developed into primary oocytes and have entered the nuclear prophase from the first meiotic division, at which point the chromosomes undergo another round of division.