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By its function, the ATM gene is ubiquitous in the body, so that the symptoms of ataxia telangiectasia are extremely varied. Thus, skin, growth and regulation of certain hormones may be affected.

Telangiectasias (spider veins) are a visible but mild sign of Ataxia telangiectasia.

Other cutaneous signs may appear during the disease. They can both be symptoms useful for diagnosis but also dangers.

 

Telangiectasia

In "Ataxia Telangiectasia", there is also "telangiectasia".

Thumbnail imageDefinition
Telangiectasia stands for an abnormal vascular expansion in size and permanence. It is red and forms a thin , tortuous line, often as an arborization or network and is most visible in the eye. Differentiation is harder on the skin as it has to be differentiated from normal dermal vessel seen by transparency.

In AT
Telangiectasia appear from 3 years, sometimes much later in adolescence, first in the eyes, and then inside the ears, eyelids, the bend of the arms and the creases of the knees. They have no effect on vision.
We do not know exactly the process of formation of these telangiectasias, except that they are almost certainly a consequence of the ATM protein deficiency on the cell cycle of vascular walls.

Treatment
There is no substantive treatment to cure them. If there is an aesthetic discomfort , they can be treated by local destruction by electrocoagulation or vascular lasers. The results are good overall, but less satisfactory for telangiectasias of the lower limbs.
Finally, it is not stated in the eye and anyway, the alteration of cells resulting from these treatments do not seem appropriate in the specific case of AT.

 

Non-infectious granulomas

A few cases of children with AT have granulomatous skin disorders that tend to spread. Granuloma means a inflammatory tumor consisting of tissue particularly rich in blood vessels and penetrated by cells of various kinds. It is not specific to a particular disease. It occurs in many diseases, including tuberculosis, sarcoidosis, leprosy and syphilis.

The granuloma is initially small, consisting of propagation, within a tissue, of a number of cells. These cells have defense capabilities and come from white blood cells (monocytes type). This is primarily macrophages that evolve into epithelioid cells and eventually form giant cells with multiple nuclei. Microscopic examination shows that they are surrounded by a wreath of white blood cells: lymphocytes.

The granuloma is most often due to a localized reaction after penetration of a germ (infectious agent). On the skin, the starting point may be only a small pustule, the site of injection of a vaccine or a local trauma as the penetration of a foreign body. The granuloma is sometimes unexplained.
As it isn't well known, the granuloma can't be treated easily. Usually, ointments are used with the initial goal of stabilizing. Skin grafts were attempted in areas heavily affected, but without success. Only the use of an intravenous anti-TNF agent (biotherapy with anti-inflammatory effect) showed some effectiveness, but there are sometimes serious side effects and reduced immunity. Thus, in the case of a patient with AT, it has to be handled with care.

 

Leuco melano dermis: pigmentation disorder

Thumbnail imageA pigmentation disorder (coloration of the skin)is sometimes observed in some patients characterized simultaneously by an excess of color (coffe stains) and a default of color (very pale areas). We talk about leuco melano dermis.
If AT is not the only disease that is concerned with this peculiarity, this disorder is part of the bundle of symptoms that characterizes it.

 

Progeria type atrophy

Progeria is a genetic disorder that, among other things, causes accelerated aging in children who suffer from it. It is partly the case of AT, particularly on the skin where there is atrophy (decrease in volume) of skin and subcutaneous cells layers: skin is thinner, sometimes wrinkled and withered, allowing to see the bony relief located below and veins more than the average.
This is due to the process of cell reproduction described in section "ATM: DNA controller" : the absent ATM protein no longer controls the cellular repair, allowing damaged skin cells to reproduce.
The skin becomes fragile and provides a more conducive ground to development of other conditions.

 

Eczema

Eczema can have many causes: repeated contact, allergy, microbe. An immune imbalance is an aggravating factor, particularly for atopic eczema, an irritant and oozing form often encountered in infants.

Seborrhea

Abnormal increase in the secretion of sebum (oily substance secreted by sebaceous glands, and whose role is to protect and lubricate the skin).
Some skin disorders are caused by excess of sebum, mainly in young individuals (acne or dermatitis). Seborrhea can also occur in some neurological diseases (Parkinson, AT) or when there is an excess of hormones (estrogen).

Abnormal sensitivity to radiation

The adverse effects of ultraviolet (UV) rays is now well known to the public. But other radiations such as X-ray radiographs, also create breaks in the DNA of cells (see Radiation"). The skin is obviously the first concerned, but for some radiation, deeper cells are also.
However, this is the heart of the target of the repair process in which the ATM protein is involved (see ATM: DNA controller" ). If the protein is inactive, the cells affected by radiation, therefore altered, can reproduce with their degeneration. Thus, the risk of cancer is increased.
More than a treatment, one must focus on prevention (see Radiation).

Hirsutism

Hirsutism is among women, hair growth on areas where it is usually present on men. In the chapter puberty, we address the dysfunctions of the reproduction apparatus in patients with AT and their consequences on the regulation of hormones. An abnormal ratio of these is most likely the cause of hirsutism observed in some patients with AT. nous abordons les dysfonctionnements des appareils de la reproduction chez les personnes atteintes d'AT avec leurs conséquences sur la régulation des hormones. Un taux anormal de celles-ci est très probablement à l'origine de l'hirsutisme observé chez certaines patientes AT.

Premature gray hair

Grey hair (or white, your choice) appear early in patients with AT. Once again, the process of DNA repair in which the ATM gene is involved (see ATM: DNA controller")is at the heart of the problem.

Thumbnail imageIndeed, the cells responsible for hair color called melanocytes (or MSC) are present initially in the form of stem cells in the hair follicle (the base of the hair). These "baby cells" CSM (or MSCs) differentiate progressively into functional cells and follow the growth of hair in normal times.
A team of Japanese researchers has shown that if these MSCs undergo aggression, chemical or radiation, which irreparably damaged their DNA, they do not necessarily die: they can still make their maturation, but remained trapped in the follicle. Not following the growing hair, they do not stain it anymore: it turns white.

These attacks take place constantly and in very large numbers. And guess who controls the repair of the MSCs, destroys them or let them turn in the wrong place? The ATM protein of course! If it is absent, the degradation occurs more rapidly.

This finding confirms the suspicions and observations: ATM is one of the molecules of aging.

Trush

Thumbnail imageIt is sometimes difficult to detect an immune deficiency in a young child. Some recurrent infections may provide a lead to the diagnosis as thrush.
Thrush is an infection that occurs in the oral mucosa, tongue, pharynx, sometimes the nails and skin folds. It is caused by a fungus, candida albicans, and develops when the defenses of the body are low. It is favored by antibiotics or acidity as in a reflux. It is more common among infants, the elderly but also the immune deficients.

Conclusion

Ataxia Telangiectasia is accompanied by many skin problems for most of which there are solutions for the treatment or prevention. Therefore, it is interesting to integrate a dermatologist in the monitoring team of AT patients.
Moreover, the now proven effects on aging of ATM may open a new field of research, particularly for the cosmetics industry and therefore, in the knowledge of the gene.

As many symptoms of ataxia telangiectasia, diabetes does not affect all people with AT.

But the ATM protein could be involved in some type of diabetes.

Diabetes is a disease linked to excess glucose in the blood (hyperglycemia), secondary to a defect in insulin production, or an insensitivity to this hormone.

Normal glucose "management"

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Video: After a meal, glucose from the digestion of food goes through the intestinal wall to the blood. Its levels in the blood increases and then prompts the pancreas to produce insulin, represented by a small green key in this video. By binding to its receptors on cell surfaces, that key "opens" the walls of the cells to glucose to allow them to function (muscle cells) or to store it (fat cells). Insulin also acts on the liver to stop or slow its production of glucose from fat reserves.


Mechanism in AT

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The difference with the above video is that the receptor on the surface of cells no longer recognizes the little green key insulin. Glucose can not get inside cells. Its levels in the blood increases dramatically and leads to the consequences described below cons.
In the case of ataxia telangiectasia, diabetes is in rare form: it would indeed present antibodies blocking the insulin that induce a major insulin resistance. Clearly, antibodies would prevent glucose from entering cells by blocking insulin. We are talking about diabetes of type 2. Result:
  1. Without "fuel", cells operate at idle.S
  2. The other body's "fuel", fatty acids, will be used.
  3. The glucose accumulates in the blood. From 1.80 g / l, it is eliminated by the kidneys which, to dissolve and evacuate it in the urine, need a lot of water.
  4. Le pancréas s'épuise à fabriquer de l'insuline.

 

Consequences

  1. Signs of fatigue appear. Faintness are possible.
  2. The use of fatty acids leads to weight loss and to the production of acetone and acid waste. Cell function is even more disturbed. The risk of nausea, vomiting or even coma is real.
  3. The evacuation by the urine and the need for water that results creates a risk of dehydration and more important thirst needed to be assuaged : the patient is urinating more and though drinking more , is dehydrating.
  4. Hyperglycemia leads to a deterioration of the arteries which become clogged and, in the long term, to a risk of impairment of heart, legs, kidneys, eyes and nerves.

 

Precautions

If, as we shall see later, type 2 diabetes in children with AT has very different causes from that of overweight people, some of the following precautions are just common sense and apply to the general population. Many of tiredness, blackouts or even accidents of life are explained by negligence that may seem elementary:

  • Have a well balanced diet, do not skip meals or snacks
  • Knowing the measures to be taken during prolonged physical activity
  • Avoid drinking alcohol without eating
  • Ask your doctor or pharmacist about the risks of taking a new medicine, herbal medicine, dietary supplement and follow the prescribed treatments , their dosage, schedules ...
The aim of this article being purely informative, you will not find all the elements directing diabetics in their life with the disease. Here are just a reminder of the basic rules: diabete
  • Measure the blood glucose regularly
  • Have permanently the glycemia meter in the vinvinity
  • Inform the entourage on the risks of hypoglycemia, how to cope with it and teach them how to control the blood sugar level
  • Wear a card mentioning his diabetes
  • Always have at least three sugars and a snack available

 

Treatment

Most current treatments are for overweight or obese adults whose increasing number also explains the expansion of type 2 diabetes. The goal is to keep a not too big but sufficient blood sugar level. Besides the necessary precautions in terms of lifestyle, some of which are mentioned above, drugs exist whose role is to regulate the glycemia. These are:

  • Biguanides which reduce production of glucose by the liver and the absorbance of glucose at the intestinal cells
  • Sulfonamides which stimulate insulin secretion by the pancreas throughout the day
  • Glinides that act the same way as sulfonamides by stimulating insulin secretion during meals
  • Inhibitors of alpha glucosidase that delay the absorption of ingested carbohydrates and slows absorption of sugars in the food

New treatments that specifically target insulin receptors on the surface of cells are being developed. It seems they are more suited to the type of diabetes that may have the children with AT.



Link with ATM ?

Thumbnail image Insulin has many similarities with the main growth factor, IGF1, Thumbnail imagewhich seems to be deficient among some children with AT (see Growth):
  • it is shown that IGF1 has the ability to pair with the insulin receptors on cells, this in a significant proportion. They even have common receptors.
  • as insulin, IGF-1 stimulates the arrival of nutrients in the muscles.
  • IGF1 has a very short lifespan in the body because it is filtered by the kidneys ... EXCEPT when it is "carried" by other proteins, thereby prolonging its action. The main one among these is IGFBP-3, also in deficit in AT. And guess who controls it? Insulin course! In other words, when the body has eaten, insulin "authorizes" the growth or the regeneration of the body by allowing IGF1 action on a long period of time.

All this does not explain why the insulin receptors on cells can not function properly in children with AT and cause diabetes. One can just see that insulin and IGF1, which has a similar malfunction for the growth part and the mechanism of which is now glimpsed, are very closely interrelated. They are also both involved in other processes of the body deficient in Ataxia Telangiectasia: aging, cancer and neuro-degeneration.

It appears that another protein, P53, directly connected with ATM in the cell cycle control (see ATM: DNA controller ), is also involved in this type of diabetes.


It has been shown as ATM has something to do with the regulation of insulin, which proves once again the extent of its functions and opens new perspectives for research.

Generally, children with ataxia telangiectasia are stunted.

The reasons for it are not known with certainty, but leads begin to emerge.

 

Possibles explanations

Three tracks can be cited to explain:

  • The first is linked to all the sometimes serious diseases these children can have. During them, such as pneumonia for example, growth is slowed by the fact that all the body resources are mobilized to fight against the disease and certain metabolic functions are affected
  • The second concerns the problems for swallowing and more generally is the result of the physical effort provided by the person with AT for feeding herself.
  • The latter is related to low rates of production of a hormone, IGF1

 

Efforts to feed oneself

When too much effort is needed to bring food or drinks to the mouth and / or swallowing, eating may not be a pleasure any more but a constraint. From there, the child with ataxia telangiectasia may diminish, unintentionally but gradually, the food quantity it absorbs and thus creating a deficit in a number of essential nutrients for growth and physical fitness .

It is therefore important to observe children's behavior regarding food and take into account any difficulty.

With theoccupational therapist, it is possible to find simple modifications to improve the body position on table and utensils (see (cf Eating).

With the Speech and Language Pathologist, it is possible to work on the swallowing to enable easier intake of the food.

But this may not be sufficient to ensure the child for normal growth. It can then be considered using a feeding gastric tube (see (cf Eating) ), which can be very effective but, like any solution, does not have only advantages and should be discussed with the doctor.

 

IGF 1 (insulin-like growth factor 1)

IGF1etGH-1Its role is only partially known but research around it intensifies. If we know that it is crucial for at least two functions, growth and aging, recent work shows that it plays a neuroprotective role in tandem with growth hormone (GH).

IGF1 is produced by the liver and stimulated by GH. The insulin has also an influence on its operation. Like it, IGF1 stimulates the arrival of nutrients in muscle, which has the effect of increasing protein synthesis and muscle mass (anabolic effect sought by some athletes).

For the growth function, it is the mediator of growth hormone (GH). In other words, when the pituitary gland releases GH , it tells the liver to produce IGF-1 which, from binding to its receptors on the surface of cells, will allow them to accept nutrients to reproduce, to grow or renew.

It is now certain that IGF1 is associated with the child in the process of growth plate cartilage of long bones and muscle development. But recent studies show that it is also involved in the growth and maintenance of brain cells and nervous system, particularly in myelination (the manufacture of insulation located around the communication cells of the nervous system, like plastic around electrical cables).

It was also shown that a continuous deficit of cell repair actions, as can be found in AT, had a direct impact on the IGF1 hormone and causes accelerated aging of cells, therefore an overall accelerated aging of the individual, as described in AT.

 

ATM and IGF1

The optimal functioning of all hormones depends not only on their rates, that is to say their production, but also on the quality of their receptors. If they are not functional, the hormone can not act.

In Ataxia Telangiectasia, low or no ATM protein leads to a double IGF1 deficiency:

  • In children with AT is found a low level of IGF1, but also of its main carrier protein, IGFBP-3, which allows it to not be eliminated by the kidneys and can act longer. However, it has been shown in AT mice that direct injection of growth hormone (GH) is not leading to the normally expected production of IGF1 by the liver, as has been explained in the preceding paragraph. This proves the role of ATM in this process. We can conclude: ATM default = production default of IGF1
  • According to researchers, the expression of IGF1 receptor (IGF1-R) that allow the cell to absorb nutrients is dependent on the ATM protein in the process of responding to DNA damage during radiation or assault (see ATM: DNA controller ). This function being deficient in ataxia telangiectasia, one can assume that the IGF1-R receptors are equally, either in number or quality, or simply because they are not enabled. Conclusion: ATM default = defects IGF1 receptor

Finally, IGF1 and ATM are also linked to other processes, such as the regulation of cholesterol and fatty acid synthesis (in connection with another protein, AMPK-?). This could explain why most children with AT have a low body mass index.

In conclusion, the trio ATM, IGF1 and GH (growth hormone) could not only explain the stunting of children with AT, but also partly the body degradation linked to ataxia telangiectasia (see Body controlo).

 

Psychology

It must be borne in mind that while some children with AT have a slow growth, they develop harmoniously and, again, this does not affect their ability nor their intellectual dévellopement.

But growth retardation, in any child, is a primarily source of complex and may require psychological support (see Psychologist).

patient helvetica, pill sans-serif; font-size: 1em; background-color: #92d2dd; border: medium solid #333333; text-align: center;">Puberty is delayed among teenagers with ataxia telangiectasia.

It is even more difficult to handle psychologically as their reproductive system is also altered.


Puberty is already a difficult passage in normal times, but it is even harder to live for children with AT as their motor problems have already taken over their lives. They also face another problem: delayed puberty like in many chronic diseases and a reproductive system which is adversely affected by Ataxia Télangienctasia.

 

Girls

The ovary contains a stock of oocytes from intrauterine life (which will then become ovums). Thus, at birth, it is of 1 to 2 million and at puberty, of 400 000. It is less than 1000 at menopause. Girls with ataxia telangiectasia have small ovaries devoid of this initial stock: this is called premature ovarian failure which unfortunately results in sterility.

 

Boys

The process is similar, spermatogenesis (the process that led to the production of male spermatozoon) being blocked from the outset. Infertility is, again, inevitable.

 

In the already very dark picture of ataxia telangiectasia, it is clear that the announcement is not without effect, so that one may wonder whether to do it. It requires in any case psychological support (see Psychologist").

In addition, hormonal deficiencies can cause developmental delays of sexual characteristics and present long-term adverse effects, with for example the risk of osteoporosis in women. The advisability of hormone replacement therapy is to discuss with the doctor, all opinions not being consistent.

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