monosomian

Monosomian is a term used in genetics to describe an organism that has only one copy of a particular chromosome, instead of the usual two. This condition arises from a non-disjunction event during meiosis, where homologous chromosomes fail to separate properly. As a result, one gamete receives both chromosomes, while the other receives none. When this gamete fertilizes with a normal gamete, the resulting zygote will have an extra chromosome in one cell and a missing chromosome in another, leading to monosomy.

Monosomy can occur in any chromosome, but it is most commonly associated with chromosome 21, leading to trisomy 21, or Down syndrome. Other monosomies can occur, such as monosomy X, which can lead to Turner syndrome in females, and monosomy Y, which is typically lethal in males. Monosomy can also occur in plants and other organisms, where it can lead to various phenotypic abnormalities.

The diagnosis of monosomy is typically made through karyotyping, a technique that visualizes the chromosomes in a cell. Treatment options for monosomy vary depending on the specific chromosome affected and the severity of symptoms. In some cases, supportive care may be the primary focus, while in others, more aggressive interventions may be necessary. Genetic counseling is often recommended for families affected by monosomy to provide information and support.