One less Chromosome:
TURNER SYNDROME.

GR Sridhar, Endocrine and Diabetes Centre, Visakhapatnam-530002
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Genes, the operational structures that determine the way we are, lie strung along the ladder -like glycoprotein skeleton in the nucleus, to form the DNA. When the genes are quiescent, as they are most of the time, the phenomenally long DNA molecule lies tightly coiled. The DNA and the protein molecules along which it is entwined is visible in the nucleus as chromosomes.

There are 23 pairs of chromosomes in each body cell of the human. Twenty two pairs are called autosomes, and are indistinguishable between men and women. The differentiation of the sexes results from the 23rd pair: women have a pair of X chromosomes (XX), whereas men have an X and a Y (XY).

Chromosomes contain the genetic material in each cell, and are therefore carefully carried forward through generations. When a chromosome is lost, the resulting cell does not usually survive. There are exceptions, such as when one of the two X chromosomes is deleted, either completely or even partially, resulting in a disorder called TURNER SYNDROME.

Girls with Turner syndrome can survive and live into adulthood. Depending on how complete the chromosomal loss, they manifest a spectrum of clinical features.

Thus Turner syndrome is a chromosomal disease which abridges linear growth and hastens reproductive senescence. This chromosomal abnormality exists right from the time of birth. Whereas normal girls have 46 chromosomes, including two X chromosomes, girls with Turner have one less X chromosome. In all, they have 45 chromosomes instead of 46. The lack of one X chromosome,which is a not uncommon condition, does not pose a danger to life, but it affects the gain in height and ovarian reproductive function.

These girls are generally short. They do not grow as tall as their peers. At the expected time of puberty, they do not have breast development, nor menstrual bleeding. If hormones are replaced, however, physical changes occur, and menstrual bleeding can be expected, depending on the size of the internal genital organs. Adequately treated, sexual function is possible, but childbearing is unlikely during the usual course of events.

Apart from this, they have a greater chance of having other diseases affecting the heart, the thyroid gland and the kidney. Therefore these disorders should be looked for, and treated if present.

Turner children are usually intelligent, and adequate scholastic performance can be expected.

Height: If children are brought to medical attention early, they can be treated with growth hormone that improves their height. While expensive, growth hormone is readily available in India. It is given as nearly painless injections every day. Treatment costs about Rs. 2-3 lakh a year, depending on the girls weight. It must be given for three to five years. Growth hormone treatment is best started by about the of age nine, or even earlier.

Adolescence: Turner children are given estrogen, the female sex hormone after the age of 14. Since their own ovaries are prematurely aged, they do not produce the hormone, which must therefore be given from outside. With estrogen therapy, breasts begin to grow, and menstrual bleeding can be expected to occur in a years time. Once menstruation sets in, another hormone, progesterone, is added for cyclic menstrual bleeding. The estrogen-progesterone tablets are continued until the age of 40 at the least.

Marriage: With adequate hormone replacement, girls with Turner syndrome are able to have normal marital relations in adulthood.

Fertility: In the usual course of events, fertility is unlikely for women with Turner syndrome. However advances in assisted reproductive technology are changing that. In vitro fertilisation ('test tube baby'), where the egg or oocyte is taken from a donor woman, can be fertilised with the husband's sperm, and implanted in the woman with Turner syndrome. With adequate hormonal and obstetric support, the normal fetus can grow to full term and be delivered.

In summary, girls with Turner syndrome have much better opportunities for treatment than even a decade ago. These girls need not always be very short, and can have regular periods. Marriage is feasible, and fertility not an impossiblity.

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