Congenital Disorders

Congenital Disorders

  Autor dr. Eugen Prajinariu Data: 15.03.2006

Congenital Disorders
The congenital disorders are a condition existing at birth. They can be structural, functional or metabolic. The similar terms are: birth defects, congenital anomalies. Many ignorant people use the term congenital anomalies, when referring to genetic diseases. 

The causes of congenital disorders are classified into genetic factors and external factors. When the causes are represented by genetic anomalies, they are inherited from parents. These genetic anomalies may be transmitted from generation to generation or not. Sometimes, there are mutations of the genetic material of the cells that will be transmitted to the descendants. 
Most mutations are very severe, even incompatible with life. The causes of these mutations are very aggressive external factors such as ionizing radiations or certain chemical substances. We are all probably thinking of those horror movies with various scaring characters called "mutants". It is true that in such cases there occur severe dysmorphisms of face and limbs, and the newborns look like monsters. There are genetic diseases transmitted from parents to children or from more or less distant 
relatives, some of them being compatible with survival but with the risk of many deficiencies in the organs functioning. Sometimes, the phenotypic characters (the exterior aspect of the body) are so subtle that can go without noticing especially in an infant, thus they will be observed only 
by a geneticist or even later during their childhood, when the parents address the doctor for functional deficiencies of the child which are actually symptoms of a genetic syndrome. 
If a newborn shows more than three disorders (morphological visible defects) than he probably is included in a genetic syndrome category, so he inherited it from the parents. Parents who had a newborn with congenital disorders without a specific cause, would better go for a genetic examination at a specialist who will present the risk of reoccurance of the disease at a future birth. 
The external environmental factors that determine the disorders are called teratogenic. They can be divided into physical, biological and chemical factors. 
The physical factors are represented by ionizing radiations, atmospheric radiations (cosmic, solar, pollution). The biological factors are the microorganisms (viruses, bacteria) or parasites (toxoplasma gondii), and also the vaccines. The chemical factors are divided into industrial substances, medicine, drugs (narcotics, alcohol, tobacco). 
From all the chemical industrial substances, very dangerous are the aromatic hydrocarbons, heavy metals (mercury, lead, arsenic, selenium), carbon monoxide, halogenated derivatives (read the article "Pregnancy and the Working Environment" from section "Pregnancy"). 
The medicine that have a real influence in the congenital anomalies are: chemotherapeutic, antithyroid, some anticonvulsants (barbiturates, hydantoin, trimethadion, sodium valproate) and antipsychotics (haloperidol, meprobamate, lithium), anticoagulants (heparin, warfarin, dicoumarol), anesthetics (halothane, pentotal and ether), TB, antipyretics (aspirin, paracetamol, indomethacin), antibiotics (chloramphenicol, tetracycline, novobiocin, amphotericin B, nalidixic acid), ephedrine. The hormonal medicine may sometimes lead to abnormalities in the genital development, pilosity, cancer at younger ages (20-25) or cardiovascular anomalies. Some vitamins which are taken excessively may cause disorders of the fetus development: vitamins A, D, K. 

Some vaccinations of the pregnant woman may determine effects on the fetus, sometime very bad according to the pregnancy age. Among these vaccines we mention: antiviral vaccines, DTaP, polio, BCG vaccines. 

The natural biological factors (microbes) are the one which interfere the most in the normal development of a pregnancy. Each type of viruses (respiratory, digestive, etc.) is are most dangerous because they reach the fetus by passing through the placenta barrier very easily. The baby who was affected by such an infection in the uterus, will be born with very severe problems, with all the organs affected, and such a disease is called TORCH syndrome. 
The effects of teratogenic agents depend on the pregnancy age that it acted. The first two weeks of the pregnancy function according to the statement "all or nothing". The interference of an external factor on this period of pregnancy might cause total damage, leading to a miscarriage, or might affect only a few cells and the embryo is developing normally. If the exposure to teratogene agent occurred in the embryo development period (from 2 to 8-9 weeks), the morphological development defects are significant and very severe, sometimes vital. After the period of 9 weeks, the organs are almost completely formed morphologically speaking, but the fetal period follows and the functional maturation of the cells takes place. The fetus starts accumulating all the nutrient he needs for the own metabolism. During this period, the teratogenic agents cause functional changes too, besides little structural ones (less severe than during the embryonic period). 
The idea is that the most sensitive period to congenital anomalies is the first trimester of the pregnancy, when there is a major risk to develop defects which are incompatible with life. It is this period when the cardiovascular and major pulmonary malformations occur, but also of other organs. The central nervous system is very sensitive in the first 2 months of pregnancy, when the morphological division takes place, but it remains vulnerable along the entire pregnancy when the functional deficiencies might occur. 
This article is not intended to present the congenital anomalies or to mention the exact agent that might cause a certain defect. It is more important for the pregnant women to know these risks in order to eliminate them timely and not to be the victim of some unpleasant events which can become real life stigmata. In the drugs category we include very many known substances whose side effects and possible teratogenic ones have been studied during pregnancy. These things are mentioned in the respective leaflets. There are also drugs which can be administered without any risk if they are taken in moderation. 

Even those which are labeled with "be careful during pregnancy", are drugs which can be taken according to the pregnancy age. The pregnant woman should not take any medicine without talking to the doctor. Regarding the other teratogenic agents, the things are very clear. Avoiding the contact with them while pregnant, especially in the first trimester is essential. 





Read the English version of this article: Congenital Disorders