Tuberous sclerosis (TSC) is a frequent hereditary autosomal-dominant disease characterised by hamartomas developing in many organs. The disorder is caused by mutations affecting either of the tumor-supressor genes, TSC1 and TSC2. Tumorogenesis is triggered by the loss of second functional gene copy, mostly accompanied by loss of heterozygosity (LOH) of flanking polymorphic markers. Search for causing mutations is very laborious, time consuming and loweffective. Prenatal diagnosis is often hampered by lack of detection of causing mutation.Detection of LOH in hamartomatous tissue suggests which gene is involved in particular case of disease and specifies which of homologous chromosomes carries germinal mutation. Examination of LOH is useful for prenatal diagnostics especially when time is lacking due to patient’s pregnancy or in case of mutation screening failure.

        Key words: tuberous sclerosis, TSC, angiomyolipoma, hamartoma, LOH, prenatal diagnostics.