Turners Syndrome

Turner syndrome is a genetic condition that only affects females. It is a chromosomal abnormality in which all or part of one of the sex chromosomes is absent or has other abnormalities (unaffected humans have 46 chromosomes, of which two are sex chromosomes). In some cases, the chromosome is missing in some cells but not others, a condition referred to as mosaicism or Turner mosaicism

Types of syndrome:

• Classic Turner syndrome - where one of the X chromosomes is completely missing
• Mosaic Turner syndrome - where one X chromosome is complete in most cells, but the other is partially missing or abnormal in some way in some cells, there may be just one X chromosome or, rarely, two complete X chromosomes

Sex chromosome:

Babies are usually born with 23 pairs of chromosomes. One pair of chromosomes determines the baby's sex. This pair is known as the sex chromosomes. One sex chromosome comes from the father and the other one comes from the mother. The mother’s contribution is always an X chromosome. The father’s contribution can either be an X or a Y chromosome. A baby girl usually has two X chromosomes (XX) and boys have an X and a Y chromosome (XY). The Y chromosome determines ‘maleness’, so if it is missing as in Turner syndrome, the sex of the child will invariably be female. A female with Turner syndrome has part or all of one X chromosome missing. This means the girl has just one complete X chromosome rather than two.

References:

• www.genome.gov
• www.nichd.nih.gov
• www.nlm.nih.gov
• www.nlm.nih.gov
• www.nhs.uk

• Short stature
• Lymphodema (swelling) of the hands and feet
• Broad chest (shield chest) and widely spaced nipples
• Low hairline
• Low-set ears
• Reproductive sterility
• Rudimentary ovaries
• Amenorrhoea, or the absence of a menstrual period
• Increased weight, obesity
• Shield shaped thorax of heart
• Small fingernails
• Characteristic facial features
• Coarctation of the aorta
• Bicuspid aortic valve
• Attention Deficit/Hyperactivity Disorder or ADHD (problems with concentration, memory, attention with hyperactivity seen mostly in childhood and adolescence)
• Nonverbal Learning Disability (problems with math, social skills and spatial relations)

References:

• www.genome.gov
• www.nlm.nih.gov

Turner syndrome is a genetic condition caused by abnormal sex chromosomes.

It only affects females who have a missing or incomplete X chromosome. 

Reference: 

• www.nhs.uk

Pre-natal tests:

Turner syndrome may be diagnosed by amniocentesis or chorionic villus sampling during pregnancy.

Often, fetuses with Turner syndrome can be identified by abnormal ultrasound findings (i.e., heart defect, kidney abnormality, cystic hygroma, ascites).

An increased risk of Turner syndrome may also be indicated by abnormal triple or quadruple maternal serum screen. The fetuses diagnosed through positive maternal serum screening are more often found to have a mosaic karyotype than those diagnosed based on ultrasonographic abnormalities, and conversely those with mosaic karyotypes are less likely to have associated ultrasound abnormalities.

Postnatal:

Turner syndrome can be diagnosed post natally at any age. Often, it is diagnosed at birth because of heart problems, an unusually wide neck or swelling of the hands and feet. However, it is also common for it to go undiagnosed for several years, typically until the girl reaches the age of puberty/adolescence and she fails to develop properly (the changes associated with puberty do not occur

A test, called a karyotype or a chromosome analysis, analyzes the chromosomal composition of the individual. This is the test of choice to diagnose Turner syndrome.

References:

• www.genome.gov
• www.nlm.nih.gov

There is no cure for Turner syndrome, but many of the associated symptoms like short stature, sexual development problems and learning difficulties, can be treated.

• Oestrogen replacement therapy such as birth control pill, has been used to promote development of secondary sexual characteristics. Oestrogens are crucial for maintaining good bone integrity, cardiovascular health and tissue health. Women with Turner syndrome who do not have spontaneous puberty and who are not treated with oestrogen are at high risk for osteoporosis and heart conditions.
• Modern reproductive technologies have also been used. For example, a donor egg can be used to create an embryo, which is carried by the Turner syndrome woman.

Reference:

• www.nhs.uk