General observations
Internal medicine training presupposes knowledge of the clinical genealogical method, syndromological approach to the diagnosis of hereditary diseases,
evaluation of the results of paraclinical studies, main traits, features of the clinical manifestations of hereditary pathology, general principles of clinical diagnostics, particularities of observation and physical examination of patients and their family members. Cytogenetic, molecular genetic, biochemical, and other laboratory tests have the highest priority for diagnostic confirmation, but they will be discussed in a separate chapter.
In clinical genetics, the term “syndrome” is used not only to designate a set of symptoms with the same pathogenesis, but also for diseases that can be considered as independent nosological units. Nosologically identified hereditary diseases are called syndromes. This is because these nosological forms were originally described as symptomatic complexes without understanding their etiology. Although later the hereditary nature (etiology) of this symptom complex or syndrome was deciphered up to its full genetic characteristics (chromosomal disorders, gene diseases, mitochondrial diseases), the term “syndrome” continued to be used to denote the hereditary diseases, first described as syndromes.
For example, after the etiology of Klinefelter syndrome has been discovered, there was an unsuccessful attempt to call it Klinefelter disease.
The terms “disease” and “syndrome” are equivalent for hereditary pathology. For some nosological forms, both terms are equally applicable, for example, Down disease, Down syndrome. However, people with Down syndrome and their caregivers are understandably sensitive about the use of terms to describe this chromosomal condition. Thereby, since the discovery of the chromosomal cause of Down syndrome in 1959, the term “trisomy 21” has been gradually adopted into use.