Diseases that are “passed from parents to children” are referred to in common parlance as hereditary diseases. Genetic diseases are divided into three groups: chromosomal abnormalities, monogenic diseases, and polygenic inherited diseases.
What are inherited diseases?
Hereditary diseases are clinical pictures or diseases that arise due to errors in the hereditary dispositions or are newly formed due to mutations (spontaneous mutation due to environmental influences, infections during pregnancy, etc.). The cause of hereditary diseases is always a change in individual chromosomes or chromosome segments (genes). Chromosomes are found in the cell nuclei of all multicellular organisms and contain the hereditary information in the form of DNA strands on which the individual genes are located. Humans have a total of 46 chromosomes in each nucleus, two of which are sex-determining (XX, XY). The remaining 44 chromosomes are crucial for the development and function of individual organs, with the individual genes being specifying.
Any chromosome or gene can be damaged and cause severe inherited diseases. In chromosomal inherited diseases, there is an abnormality in chromosome number or structure. Known hereditary diseases in this category are trisomy 21 (Down syndrome), Klinefelter syndrome (XXY) and Turner syndrome (only one X chromosome). These inherited disorders often manifest with decreased intelligence, altered physiognomy, and physical impairments of varying severity. In a monogenic disorder, only one gene is defective. These hereditary diseases occur frequently, impede and hinder, for example, the formation of enzymes and proteins, and are responsible for most metabolic diseases. Hemophilia, sickle cell anemia and albinism are also among these inherited diseases. Monogenic defects can be inherited, but can also arise spontaneously. In polygenic or multifactorial inherited diseases, several genes are affected that act together in a defective manner. Often environmental influences are additionally decisive. This applies, for example, to cleft palate, hereditary forms of schizophrenia, and some allergies.
Typical and common hereditary diseases
- Down syndrome (trisomy 21)
- Turner syndrome
- Cleft lip and palate (cheilognathopalatoschisis)
- Renal cyst (cystic kidneys)
- Alpha-1 antitrypsin deficiency
- Cystic fibrosis
- Hemophilia (bleeding disorder)
- Phenylketonuria (PKU)
- Huntington’s disease (Huntington’s disease)
Symptoms, complaints and signs
Due to the large number of hereditary diseases, it is impossible to describe symptoms and complaints in a unified way. However, most hereditary diseases are characterized by the fact that the symptoms associated with them appear at a certain point in life and eventually worsen. In many cases, they mean a lifelong limitation of the affected person and can shorten his or her life span, sometimes considerably. Symptoms include metabolic disorders, nerve degeneration and genetic blindness. Because a genetic predisposition to certain conditions can also be defined as a hereditary disease in the broadest sense, in some cases conditions such as heart attacks, an increased susceptibility to tumor formation and osteoporosis also fall within the circle of symptoms. Signs of hereditary diseases often consist of offspring showing symptoms that were already known in parents or grandparents. The suspicion of the presence of a hereditary disease is then obvious. However, this can only be quickly assumed in the case of autosomal-dominant inheritance, since autosomal-recessive inheritance can be inherited for one or more generations without the expression of a disease. To get an overview of the symptoms and possible signs of a hereditary disease, it is useful for descendants of tendentious carriers of such genes, as well as the tendentious carriers themselves, to become familiar with the corresponding probabilities of inheritance and occurrence.
Diagnosis and progression
An accumulation of certain diseases in the family may indicate hereditary diseases. Monogenetic defects are difficult to diagnose and are readily referred to as “predisposition” rather than hereditary disease.Whether and how severe the individual clinical pictures occur in the more relevant chromosomal inherited diseases depends on whether only parts of a chromosome are damaged, a chromosome is missing completely or even occurs twice. Sex-specific hereditary diseases (X, XXY) are often associated with inferior intelligence and/or infertility. Most damage to the chromosomal genome does not produce a viable organism. Nature helps itself with these acute hereditary diseases and the embryo is rejected. Many hereditary diseases thus remain undetected. Carriers of a genetic defect do not have to have the corresponding clinical picture themselves, but they can inherit the defect recessively or dominantly. Incestuous unions often produce offspring with hereditary diseases.
Complications depend very much on the hereditary disease itself and its treatment. In many cases, it is possible to limit and control the symptoms and complications with early treatment. In severe cases, however, treatment is not directly possible, so that only the symptoms can be treated to make life and everyday life easier for the patient. In most cases, hereditary diseases cause problems with intelligence and motor skills. Thus, mental and physical retardation occurs. This leads to severe social problems, bullying and teasing, especially in children. In some hereditary diseases there is a strong reduction of life expectancy due to the expression of different diseases. This is especially the case when the immune system is significantly weakened and cannot provide a lasting defense. A hereditary disease cannot be treated originally, so that the treatment is designed only to reduce the symptoms. In many cases, therapies are possible that limit the symptoms and allow the patient to live a healthy life.
When should you see a doctor?
Hereditary diseases should definitely not be taken lightly, so an examination by an appropriate specialist should definitely take place. Some hereditary diseases can even be detected immediately after birth, so subsequent care by a doctor is mandatory. Of course, it is always significant what kind of hereditary disease is present. Some hereditary diseases require regular treatment as well as medical interventions to avoid serious consequential damages. Of course, the intensity of subsequent treatment always depends on the particular hereditary disease. In some cases, only a preventive examination is necessary, so that a permanent treatment by an appropriate physician does not have to take place. In other cases, certain hereditary diseases require regular examination or treatment, as otherwise permanent or even fatal consequential damage may occur. For this reason, the following applies: An examination for hereditary diseases should definitely take place for every person. Through such an early examination, a possible hereditary disease can be detected, so that possible complications can be avoided.
Treatment and therapy
Amniocentesis can detect most chromosomal inherited diseases at the embryonic stage. Affected parents must ultimately decide for themselves whether to give life to a disabled child. However, the origins of the hereditary diseases are currently untreatable. Only the symptoms can be alleviated with medication. Thus, mentally handicapped children with trisomy 21 are now allowed to lead a largely independent life in adulthood, which is achieved, among other things, through targeted support. The life expectancy of people with a hereditary disease (e.g. cystic fibrosis) has also increased significantly as a result of advances in medical science. Children with congenital, hereditary hypothyroidism used to be inevitably classified as “feeble-minded” and suffered from short stature. The clinical picture of this hereditary disease was called cretinism. Today, the disease is suppressed by the administration of artificial thyroxine (thyroid hormone) and iodine, and the children can develop normally. Many hereditary diseases have lost their stigma and are successfully treatable, although not (yet) curable.
Outlook and prognosis
The prognosis of hereditary diseases is to be determined according to the individual disease.Since human genetics must not be interfered with, fundamental changes to the DNA are not possible. Hereditary diseases can therefore only be treated symptomatically. There are diseases in which good results can be achieved by treating the symptoms that arise and a stable quality of life can be achieved. Surgical interventions offer countless possibilities for corrections, which contribute to an improvement of the situation. Often, however, several operations have to be performed in the course of a patient’s life to ensure survival. Due to medical progress, scientists continuously succeed in finding new methods or possibilities for treatment as well as successfully implementing them. Nevertheless, there are parallel hereditary diseases for which medicine can apply no or only a few therapeutic methods. Often the lifespan of the diseased person is significantly reduced in the case of genetic defects. In addition, a reduced development, optical abnormalities or mental as well as motoric limitations are to be expected. In addition to the physical characteristics of a hereditary disease, this often results in mental illnesses that can further worsen a prognosis. In some cases, a fetus or a newborn child is not able to survive. It dies in the womb or shortly after birth despite all efforts.
Early detection of hereditary diseases is important to reduce the effects on the body and mind, as well as impairments in quality of life. Genetic defects that affect metabolism are now readily treatable. Early treatment reduces the severity of the clinical picture caused by such hereditary diseases and allows affected individuals to lead largely normal lives.
In many inherited diseases, follow-up care is very difficult. Genetic defects or mutations can have such serious consequences that medical professionals can mitigate, correct, or treat only a few of them. In many cases, hereditary diseases cause severe disabilities. Those affected have to struggle with these for the rest of their lives. What can be done in aftercare often enough consists only of physiotherapeutic or psychotherapeutic measures. However, treatment successes can be achieved for a whole range of slowly progressing hereditary diseases. What these look like depends on the disease itself. Hereditary diseases such as hemophilia, cystic fibrosis or Down syndrome each have very different clinical pictures. The same applies to cleft palate, neurofibromatosis or cystic kidneys. Follow-up measures must be based on these clinical pictures. Generalized statements about the type of aftercare are only permissible to the extent that life is made easier for the affected patients if possible. Hereditary diseases can cause increasing or consistently severe symptoms throughout life. They can considerably limit the quality and length of life. For many hereditary diseases, surgery provides little relief. Postoperative follow-up may be necessary. Some of the symptoms or disorders of hereditary diseases can be successfully treated nowadays. Psychotherapeutic care is useful for hereditary diseases where depression, feelings of inferiority, or other psychological disorders occur as a result of the characteristics of the disease.
What you can do yourself
Hereditary diseases are genetic and are passed from one generation to subsequent generations. Against the causes of a hereditary disease, the affected person himself usually can not take any action. Conventional medicine is currently also generally unable to treat a genetically caused disease causally. In many cases, however, those affected can help to control the risks or mitigate the severity of the course of the disease. What an affected person can specifically do himself, however, depends on which hereditary disease he suffers from or which hereditary diseases have already occurred in the family. In the case of many hereditary diseases, a severe disorder can already be detected during prenatal diagnostics. Expectant parents in whose families one or more hereditary diseases are prevalent should therefore make use of the preventive examinations offered. They can then decide whether to terminate the pregnancy prematurely in the event of a severe disability. Some hereditary diseases, on the other hand, do not become apparent until adulthood.Here, the course of the disease and the prognosis for the affected person often depend on the disorder being recognized early and treated adequately. Persons in whose families hereditary diseases occur should familiarize themselves with the course and accompanying symptoms of the diseases so that they can correctly interpret even the first symptoms and seek medical help promptly.