Difference Between Turner Syndrome and Down Syndrome

Down and Turner syndromes are both chromosomal disorders, although they differ in the chromosomes involved, as well as in their prevalence, aetiology, symptoms, diagnosis, and prognosis.

What is Down Syndrome?

John Langdon was the first to describe Down Syndrome (DS). Down syndrome, named for a late-nineteenth-century English physician, is caused by a complete or partial copy of chromosome 21 in 1 in 700 newborns in the United States.

Causes − The source of the extra partial or whole chromosome in Down syndrome is still unclear, however the maternal age has been recognised as a factor. A 20-year-old woman has a 0.1% chance of having a child with Down syndrome, whereas a 45-year-old mother has a 3% risk. In around 5% of instances, the origin may be traced back to the father.

Types − Multiple types of Down Syndrome cases have been discovered−

  • Trisomy 21 occurs when a pair of chromosomes 21 in the sperm or ovum does not split, either before or during conception. This results in three copies of chromosome 21, rather than the usual two. These can spread to and multiply in any cell in the body.

  • About 4% of those with DS have translocation DS. Here, there are 46 chromosomes since chromosome 21 has been copied and joined to another, usually chromosome 14. About a third of these instances have a known genetic link.

  • One percent of DS cases are mosaic, caused by cells with 46 chromosomes and others with 47.

Characteristics − Low muscular tone, a somewhat flattened facial profile, an upward tilt to the eyes, short height, and a single deep furrow across the hands are all physical characteristics of Down syndrome. Young adults with the disorder often have the IQ of a child of eight or nine years old, as well as experiencing physical growth delays and mild to severe intellectual disabilities.

Diagnosis − Blood serum testing and an ultrasonography can detect DS indicators in a foetus. First trimester chronic villus sampling and second trimester amniocentesis are more intrusive but more accurate diagnostic techniques. The diagnostic tests both carry a 1% chance of causing a spontaneous abortion, yet they are both quite accurate.

When prenatal screening results reveal Down syndrome, the embryo is often discarded. DS can be diagnosed immediately after delivery by observing the baby for the aforementioned physical symptoms and taking blood for genetic testing.

Prognosis − There is currently no treatment or cure for DS or TS because they are both inherited illnesses. In the industrialised world, a person with DS may expect to live until they are 50 or 60 years old with the help of specialised education programmes and a sheltered workplace.

What is Turner Syndrome?

Turner Syndrome (TS) occurs exclusively in females with a single X chromosome as opposed to two. Approximately 1% of embryos contain TS, yet 99% of these embryos spontaneously abort, most frequently during the first trimester, resulting in approximately 1 in 2500 live births globally.

TS is a hereditary condition that only affects women. The condition develops when the majority of cells lack or have an incomplete X chromosome. Sexual maturity is delayed in girls with TS.

Characteristics − A webbed neck, wide chest, low height, receding chin, aberrant forearm angles, short fingers, and delayed sexual maturation are also hallmarks of TS.

Diagnosis − At birth, TS can be diagnosed by observing the baby's physical traits and taking blood for genetic testing. The inability to start menstruating at the expected time can be a clue that a person has TS, but because most persons with TS are of average intellect, the disorder may not be recognised until puberty. However, spatial vision impairments have been reported to be above average.

Prognosis − Females with TS can have a somewhat normal life because to hormone therapy that promote the development of healthy hips and breasts, they are unable to become pregnant without medical assistance.

Differences between Turner Syndrome and Down Syndrome

The following table highlights the major differences between Turner Syndrome and Down Syndrome −


Turner Syndrome

Down Syndrome


1 in 700 male and female infants.

1 in 2500 females.


It is diagnosed at birth.

It is diagnosed during adolescence.


The chromosomal defects that result in Turner and Down syndromes are distinct. A missing or mutated X chromosome causes TS, whereas an extra copy of chromosome 21 causes DS. While DS can affect both sexes, TS only affects girls and is often not recognised until adolescence. Differential sex susceptibility is linked to infertility, whereas Down syndrome is associated with mild to moderate mental retardation.

Updated on: 31-Jan-2023

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