Updated by: Arabinda Naik
Down Syndrome
The result of an extra copy of chromosome 21. Down syndrome affects 1: 700 children and alters the child's phenotype either moderately or severely. These people can have heart defects, short stature, susceptibility to respiratory disease, shorter than average lifespan, can develop. Alzheimer's and leukaemia easier. This syndrome can be correlated with the age of the mother but can be the result of Nondisjunction of the father's chromosome 21.
Patau Syndrome
The result of an extra copy of chromosome 13. These people have serious eye, brain, circulatory defects as well as cleft palate. This can affect 1 :5000 live births and children rarely live more than a few months.
Edward's Syndrome
The result of an extra copy of chromosome 18. The child has almost every organ system affected. This effects about 1: 10 000 live births. Children with this disorder do not live more than a few months.
These disorders can be fatal, but many people have these karyotypes and are fine.
Klinefelter Syndrome
There are two things that can happen
1. The result of two X karyotypes and one Y karyotype.
These effects the males sex organs becoming sterile and develops more feminine body characteristics than male.
2. The result of one X karyotype and two Y karyotypes.
This people with this disorder is somewhat taller than average and often have below normal intelligence.
Trisomy X
The result in three X karyotypes and no Y karyotypes in women. This can affect 1: 1000 live births they are healthy and fertile but usually cannot be distinguished from normal female.
Monosomy X (Turner's syndrome)
The result of only a single X karyotype in women. This effects 1 :5000 live births women with Turner's have only forty-five chromosomes (normal is forty-six) These people are genetically female, but they do not mature sexually during puberty and are sterile. Ninety-eight percent of these fetuses die before birth.