At the beginning of the 21st century, there are already more than 6 thousand types of hereditary diseases. Now many institutes of the world are studying hereditary human diseases , the list of which is huge.
The male population has more and more genetic defects and less chance of having a healthy baby. While all the reasons for the development of defects are not clear, it can be assumed that in the next 100-200 years, science will cope with the solution of these issues.
What are genetic diseases? Classification
Genetics as a science began its research path since 1900. Genetic diseases are those that are associated with abnormalities in the human gene structure. Deviations can occur both in 1 gene or in several.
Hereditary diseases:
- Autosomal dominant.
- Autosomal recessive.
- Interlocked with the floor.
- Chromosomal diseases.
The probability of a child's disease with autosomal dominant deviation is 50%. With autosomal recessive - 25%. Diseases linked to the floor are those that the damaged X chromosome carries with it.
Hereditary diseases
Here are a few examples of diseases, according to the above classification. So, the dominant recessive diseases include:
- Marfan's syndrome.
- Paroxysmal myoplegia.
- Thalassemia.
- Albright's disease.
- Otosclerosis .
Recessive:
- Phenylketonuria.
- Ichthyosis.
- Others.
Sex-linked diseases:
- Hemophilia.
- Muscular dystrophy.
- Farby's disease.
Also on hearing are chromosome inherited human diseases. The list of chromosomal abnormalities is as follows:
- Shereshevsky-Turner syndrome.
- Klinefelter's syndrome.
- Feline scream syndrome.
- Down Syndrome.
Polygenic diseases include:
- Hip dislocation (congenital).
- Heart defects.
- Schizophrenia.
- Splitting of lips and palate.
The most common gene abnormality is syndactyly. That is, finger jointing. Syndactyly is the most harmless disorder and is treated thanks to surgery. However, this deviation also accompanies other more serious syndromes.
Which diseases are most dangerous?
Of the listed diseases, the most dangerous hereditary diseases of a person can be distinguished. Their list consists of those types of anomalies where trisomy or polysomy is found in the chromosome set, that is, when instead of a pair of chromosomes, 3, 4, 5 or more are observed. There is also 1 chromosome instead of 2. All these abnormalities occur due to impaired cell division.
The most dangerous hereditary human diseases:
- Edwards Syndrome.
- Spinal muscular amyotrophy.
- Patau Syndrome.
- Kanavan's disease.
- Hemophilia.
- Other diseases
Due to such violations, the child lives a year or two. In some cases, the deviations are not so serious, and the child can live up to 7, 8, or even up to 14 years.
Down Syndrome
Down syndrome is inherited if one or both parents are carriers of defective chromosomes. More specifically, the syndrome is associated with trisomy of chromosome 21 (i.e. 21 chromosomes 3, not 2). Children with Down syndrome have strabismus, a crease on the neck, an abnormal shape of the ears, heart problems, and mental retardation. But for the life of newborns, the chromosomal abnormality is not dangerous.
Now statistics say that out of 700-800 children, 1 is born with this syndrome. Women who want to have a baby after 35 are more likely to have such a baby. The probability is somewhere 1 to 375. But a woman who decides to have a baby at 45 has a probability of 1 to 30.
Acrocraniodysphalangia
The type of inheritance of the anomaly is autosomal dominant. The cause of the syndrome is a violation in the 10th chromosome. In science, this disease is called acrocraniodysphalangia, if simpler, then Apert syndrome. It is characterized by such structural features of the body as:
- brachycephaly (violation of the ratio of the width and length of the skull);
- fusion of the coronary sutures of the skull, as a result of this there is hypertension (high blood pressure inside the skull);
- syndactyly;
- convex forehead;
- often mental retardation against the background of the fact that the skull compresses the brain and prevents nerve cells from growing.
Nowadays, children with Apert syndrome are prescribed surgery to enlarge the skull to restore blood pressure. And mental underdevelopment is treated with stimulants.
If there is a child in the family who is diagnosed with the syndrome, the probability that 2 children will be born with the same deviation is very high.
Happy Doll Syndrome and Canoevan-Van Bogart-Bertrand Disease
Let us consider in more detail these diseases. Engelman's syndrome can be recognized somewhere from 3-7 years. Children have cramps, poor digestion, problems with coordination of movements. Most of them have strabismus and problems with the muscles of the face, which is why a smile is often on the face. The movements of the child are very constrained. For doctors, this is understandable when a child tries to walk. Parents, in most cases, do not know what is happening and the more so with what it is connected. A little later, it is noticeable that they cannot speak, just try to mumble something inarticulate.
The reason a child manifests a syndrome is a problem on the 15th chromosome. The disease is extremely rare - 1 case per 15 thousand births.
Another disease - Kanevan disease - is characterized by the fact that the child has weak muscle tone, he has problems with swallowing food. The disease is caused by damage to the central nervous system. The reason is the defeat of one gene on the 17th chromosome. As a result, the nerve cells of the brain are destroyed with progressive speed.
Signs of the disease can be seen at 3 months of age. Kanavan disease manifests itself as follows:
- Muscle hypotension.
- Macrocephaly.
- Seizures appear at one month of age.
- The child is not able to hold his head upright.
- After 3 months, tendon reflexes increase.
- Many children go blind by age 2.
As you can see, hereditary human diseases are very diverse. The list provided for example purposes is far from complete.
I would like to note that if both parents have a violation in the same gene, then the chances of having a sick child are great, but if the anomalies are in different genes, then you can not be afraid. It is known that in 60% of cases, chromosomal abnormalities in the embryo lead to miscarriage. But still 40% of these children are born and fight for their lives.