In line with its mission, the Editorial Board of MedTvoiLokony makes every effort to provide reliable medical content supported by the latest scientific knowledge. The additional flag “Checked Content” indicates that the article has been reviewed by or written directly by a physician. This two-step verification: a medical journalist and a doctor allows us to provide the highest quality content in line with current medical knowledge.
Our commitment in this area has been appreciated, among others, by by the Association of Journalists for Health, which awarded the Editorial Board of MedTvoiLokony with the honorary title of the Great Educator.
X-linked diseases can be both recessive and dominant. If the disease is inherited recessively, symptoms only occur in men.
For symptoms of a recessively inherited disease, you normally need two copies of the mutant gene – one from each parent. On the X chromosome, where the male has only one and does not have the correct copy of the gene, he will develop symptoms of the disease. If a certain trait is present in several males related by females, X-linked inheritance may be suspected among them.
Criteria for this type of inheritance:
– sick men have healthy daughters and healthy sons if the disease is recessive
– if the disease is dominant, all daughters of a sick man will be sick
– female carriers are healthy but transmit the mutation to 50% of their sons and 50% of their daughters. The remaining 50% of daughters are healthy people without the mutated gene
– in this type of inheritance there is no transmission of the disease from father to son
– sick women are most often the offspring of a sick man and a female carrier
Duchenne muscular dystrophy
It is a disease that is transmitted by women and only affects men. According to various authors, the first symptoms appear between the ages of 1 and 4. Characteristic changes relate to symmetrical weakness and muscle atrophy. It usually starts at the lap belt, causing a shaky, duck-like gait, problems getting up from a sitting position, and climbing stairs. Pseudo hypertrophy of the calf muscles is common. During the course of the disease, contractures appear, which immobilize sick boys until the age of 10. There are also cases of mental retardation. Muscle atrophy usually up to the age of 20. lead to death due to respiratory and heart failure.
There is currently no effective treatment for this dystrophy or other diseases in this group. It is possible, however, to slow down the progress of the symptoms of the disease by mild physiotherapy and try to keep the child active for as long as possible. Genetic counseling with carrier detection is very important in this disease.
Fragile X syndrome (Fra X)
this syndrome is the most common cause of hereditary mental retardation, usually mild to moderate. It occurs in about 1 in 1500 men. Characteristic features also include large ears and a protruding chin, as well as enlarged testicles. In many cases, there are speech disorders and autistic symptoms.
There is also an interesting phenomenon in the inheritance of disease called the Sherman Paradox. He says that the probability of having a mental retardation in a family is higher the greater the number of generations through which the mutation has been passed on.
Other X-linked inheritance disorders include:
– color blindness
– fish scales
— hemofilia A i B
Text: lek. med. Roma Roemer-Ślimak