Mongolism Health Dictionary

Mongolism. Trisomy 21. Not a disease but a defect in mental and physical development. In the normal human being there are 46 chromosomes; in Down’s there are 47 – one extra No 21 chromosome. The syndrome increases with the age of the mother after the age of 35. Over the age of 40 the chances of a mother having such a child are 1-2 per cent. Children with the defect have low levels of zinc.

Cases of Down’s have followed use of nonoxynol-9 (vaginal contraceptive device) such as the polyurethane sponge. The sponge. when left in situ for a long time, may cause Down’s to follow.

Certain physical characteristics are present. The most important feature is impaired mental development. Almost all are coeliacs.

Symptoms. Low IQ, short fingers, small flat head, flattened nose, low-set ears. May be subject to umbilical hernia, and heart disease. No treatment can cure, but certain herb teas rich in minerals (Alfalfa, Red Clover) together with Kelp (either in tablet or powder form) may help children, with possible improvements in IQ. Vitamin supplements – A, D, Thiamine, Riboflavin, B6, B12, C and E improve a child’s physical and mental health – as do also the minerals: Magnesium, Calcium, Zinc, Manganese, Copper, Iron and Iodine.

Children with Down’s syndrome run an increased risk of coeliac disease, due to disturbed immunity. A substantial evidence is held in America that links a low level of Selenium in the mother. Unnecessary X- rays should be avoided. Ensure fitness before conception by gentle exercise and nutrients: Folic Acid, Selenium and Zinc.

Children with the condition are noted for their happy disposition and warmth of feeling towards others. ... down’s syndrome

A genetic disorder in which the affected person usually carries an extra chromosome – 47 instead of the usual 46. The extra chromosome occurs in the no. 21 group, hence the disorder is described as trisomy 21. The condition was named after Dr J L H Down, the London doctor who ?rst described it in 1866. The incidence is around one in 600 births. The disorder is characterised by a particular physical appearance and learning diffculties, with the affected individuals having an INTELLIGENCE QUOTIENT (IQ) ranging from 30 to 80 (normal is 100). Most people with the syndrome have eyes that slope up at the outer corners with skin folds that cover the inner ones. The face and features are smaller than normal, while the tongue is larger; the back of the head is ?attened and the hands are usually short and broad. The facial features led to the syndrome being described as ‘mongolism’, a term that is no longer used.

Children with Down’s syndrome are usually friendly and ?t in well with the family. Despite their learning disabilities, some learn to read and, if they have appropriate educational and environmental stimulation, can make the most of their abilities.

A heart defect is present in around 25 per cent of the children at birth, and deafness and acute LEUKAEMIA occur more frequently than in unaffected youngsters. Those with the syndrome are particularly prone to developing ear infections. ATHEROSCLEROSIS often develops early in adults and ALZHEIMER’S DISEASE tends to occur as early as 40 years of age. A friendly home environment helps them to enjoy life, but a few individuals with the syndrome may eventually require institutional care. Improved social and medical care means that many now live until their 60s.

Routine screening tests early in pregnancy, starting with blood analysis but going on if necessary to AMNIOCENTESIS and chorionic villus sampling (see PRENATAL SCREENING OR DIAGNOSIS), can identify fetuses likely to develop the disorder. If a sample of fetal cells con?rms the chromosome defect (triple marker test – see PREGNANCY AND LABOUR), the parents may consider termination of the pregnancy. In the UK, screening is normally o?ered to women over 35 because of their increased risk. When younger parents have a child with Down’s syndrome, the chances of a subsequent child with the disorder are relatively high as it is probable that both parents carry a chromosome abnormality insu?cient to cause ill-health until combined. So they may wish to discuss with their medical advisers the question of further pregnancies.

Parents who have a child with Down’s syndrome will understandably feel a combination of strong emotions, including anger and guilt, and constructive counselling can be valuable. Among societies o?ering advice and support is the Down’s Syndrome Association.... down’s (down) syndrome

In humans there are 23 pairs of CHROMOSOMES. Male and female di?er in respect of one pair. In the nucleus of female cells, the two members of the pair are identical and are called X chromosomes. In the male nucleus there is one X chromosome paired with a dissimilar, di?erently sized chromosome called the Y chromosome. In the sex cells, after MEIOSIS, all cells in the female contain a single X chromosome. In the male, half will contain an X chromosome and half a Y chromosome. If a sperm with an X chromosome fertilises an ovum (which, as stated, must have an X chromosome) the o?spring will be female; if a sperm with a Y chromosome fertilises the ovum the o?spring will be male. It is the sex chromosomes which determine the sex of an individual.

Sometimes during cell division chromosomes may be lost or duplicated, or abnormalities in the structure of individual chromosomes may occur. The surprising fact is the infrequency of such errors. About one in 200 live-born babies has an abnormality of development caused by a chromosome, and two-thirds of these involve the sex chromosomes. There is little doubt that the frequency of these abnormalities in the early embryo is much higher, but because of the serious nature of the defect, early spontaneous ABORTION occurs.

Chromosome studies on such early abortions show that half have chromosome abnormalities, with errors of autosomes being three times as common as sex chromosome anomalies. Two of the most common abnormalities in such fetuses are triploidy with 69 chromosomes and trisomy of chromosome 16. These two anomalies almost always cause spontaneous abortion. Abnormalities of chromosome structure may arise because of:

Deletion Where a segment of a chromosome is lost.

Inversion Where a segment of a chromosome becomes detached and re-attached the other way around. GENES will then appear in the wrong order and thus will not correspond with their opposite numbers on homologous chromosomes.

Duplication Where a segment of a chromosome is included twice over. One chromosome will have too little nuclear material and one too much. The individual inheriting too little may be non-viable and the one with too much may be abnormal.

Translocation Where chromosomes of different pairs exchange segments.

Errors in division of centromere Sometimes the centromere divides transversely instead of longitudinally. If the centromere is not central, one of the daughter chromosomes will arise from the two short arms of the parent chromosome and the other from the two long arms. These abnormal daughter chromosomes are called isochromosomes.

These changes have important bearings on heredity, as the e?ect of a gene depends not only upon its nature but also upon its position on the chromosome with reference to other genes. Genes do not act in isolation but against the background of other genes. Each gene normally has its own position on the chromosome, and this corresponds precisely with the positon of its allele on the homologous chromosome of the pair. Each member of a pair of chromosomes will normally carry precisely the same number of genes in exactly the same order. Characteristic clinical syndromes, due to abnormalities of chromosome structure, are less constant than those due to loss or gain of a complete chromosome. This is because the degree of deletion, inversion and duplication is inconstant. However, translocation between chromosomes 15 and 21 of the parent is associated with a familial form of mongolism (see DOWN’S (DOWN) SYNDROME) in the o?spring, and deletion of part of an X chromosome may result in TURNER’S SYNDROME.

Non-disjunction Whilst alterations in the structure of chromosomes arise as a result of deletion or translocation, alterations in the number of chromosomes usually arise as a result of non-disjunction occurring during maturation of the parental gametes (germ cells). The two chromosomes of each pair (homologous chromosomes) may fail to come together at the beginning of meiosis and continue to lie free. If one chromosome then passes to each pole of the spindle, normal gametes may result; but if both chromosomes pass to one pole and neither to the other, two kinds of abnormal gametes will be produced. One kind of gamete will contain both chromosomes of the pair, and the other gamete will contain neither. Whilst this results in serious disease when the autosomes are involved, the loss or gain of sex chromosomes seems to be well tolerated. The loss of an autosome is incompatible with life and the malformation produced by a gain of an autosome is proportional to the size of the extra chromosome carried.

Only a few instances of a gain of an autosome are known. An additional chromosome 21 (one of the smallest autosomes) results in mongolism, and trisomy of chromosome 13 and 18 is associated with severe mental, skeletal and congenital cardiac defects. Diseases resulting from a gain of a sex chromosome are not as severe. A normal ovum contains 22 autosomes and an X sex chromosome. A normal sperm contains 22 autosomes and either an X or a Y sex chromosome. Thus, as a result of nondisjunction of the X chromosome at the ?rst meiotic division during the formation of female gametes, the ovum may contain two X chromosomes or none at all, whilst in the male the sperm may contain both X and Y chromosomes (XY) or none at all. (See also CHROMOSOMES; GENES.)... sex chromosomes