There are almost 6000 different genetic diseases worldwide. Their causes are as diverse as the symptoms that result from it.
There is not a genetic disease but genetic diseases with each its particularities. They are triggered by the presence of one or more defective genes or chromosomes. This abnormality affects the number of chromosomes and the structure of chromosomes.
Larger abnormalities may be visible under a microscope during a test called chromosome analysis or karyotype determination. Smaller chromosomal abnormalities can be identified through a specialized genetic test, which analyzes a person’s chromosomes to detect extra or missing parts.
Cystic fibrosis or Down’s syndrome. How are genetic diseases screened? What are the risks of transmission to children?
What is a genetic disease?
The human body has 46 chromosomes (23 pairs, each consisting of a chromosome of paternal origin and a chromosome of maternal origin). These are made up of DNA carrying our genes. A genetic disease is characterized by the presence of one or more defective genes or chromosomes.
If the anomaly affects a chromosome, it is called a chromosomal anomaly. There may be an extra chromosome (or part of a chromosome) on a pair (as in the case of trisomy) or one less chromosome (monosomy).
If the abnormality affects a DNA gene, it is called a mutation. These mutations cause dysfunctions in the body. The disease can be monogenic (mutation of a gene) or polygenic (mutation of several genes). If the abnormal gene is dominant, it determines a so-called “dominant” disease, while, if it is recessive, the diseases appear when the child receives the same gene from both parents (the disease is called “recessive”). A genetic disorder is not contagious. It cannot be transmitted by air or contact.
They can appear at any age
Genetic diseases vary in severity, which can range from lethality before birth to the need for permanent care. They appear at all stages of life, from birth or early childhood (cystic fibrosis or Duchenne muscular dystrophy) to adulthood (Huntington’s chorea).
A genetic disease is not necessarily hereditary. It can be inherited from parents or acquired (anomalies occurring in the production of sperm and oocytes and transmissible to descendants or occurring during life as in cancer. Here, the mutation is not transmitted and is not inherited ).
Worldwide, at least 7.6 million children are born each year with a serious genetic or congenital disability. In developed countries, genetic diseases and congenital disabilities are the second most common cause of death in infants and children, and their prevalence at birth is at the highest of 25-60 per 1000.
Screening and diagnosis
Different symptoms may prompt the doctor to request an analysis of the patient’s DNA and chromosomes to detect a genetic abnormality. The test is carried out by a blood test in a specialized laboratory. The laboratories work in a network for the screening of genetic diseases. When diagnosing a genetic condition, medical and psychological support for the patient is essential. It will be monitored by different professionals: physiotherapists, psychologists, neurologists, clinical geneticists, etc.
Who are the people at risk?
Everyone is at risk of disease due to genetic mutations. But social or cultural factors (consanguineous marriages) increase the risks of transmission. Also, maternal age over 35 is associated with a higher frequency of chromosomal abnormalities in children.
The most common genetic diseases (thalassemia, cystic fibrosis, hemophilia, and phenylketonuria) can be well managed. Their effective treatment is beneficial since it increases life expectancy and improves the quality of life.