[Breast cancer in monozygotic twins]. / Karcinom prsu u monozygotních dvojcat.

SUMMARY: Breast cancer is a multifactorial disease. Twin studies comparing the disease concordance rate in identical twin pairs serve to differentiate the influence of genetic and environmental factors in the disease development. AIM OF THE STUDY: To assess breast cancer risk for an identical twin sister of a patient with breast cancer. PATIENTS AND METHODS: Five monozygotic twin families were examined during 2005- 2011 in which at least one of the monozygotic sisters developed breast cancer.In 4 breast cancer women from 4 families, molecular genetic analysis of BRCA1 and BRCA2 genes was performed. RESULTS: The median followup period was 12.6 years (7 to 24 years). No pair of monozygotic sisters was concordant for breast cancer. Familial breast/ ovarian cancer syndrome due to BRCA1 gene mutation was confirmed in one pair. These twins were phenotypically discordant, the first one developing breast cancer at the age of 54 years, her co sister suffering from ovarian cancer at the age of 43 years. In the other 4 nonBRCA families, breast cancer was diagnosed at the age of 38- 50 years (median 44 years) in one of the sisters; the other twins remain healthy through the followup period. CONCLUSION: We did not observe concordance for breast cancer in 5 pairs of monozygotic twins. Based on results of published studies, the life  time breast cancer risk for a healthy identical twin of a breast cancer nonBRCA woman is around 20- 30 %. Other nonhereditary risk factors must exist to explain the discordant phenotype. This highlights that environmental factors play an important role in breast cancer development. In case of BRCA associated breast cancer, breast cancer risk for the healthy co twin is the same as that for other BRCA mutation carriers, i.e. 45- 85%.

[Hereditary leiomyomatosis and renal cell cancer - HLRCC/multiple cutaneous and uterine leimomyomatosis - MCUL]. / Hereditární leiomyomatóza a renální karcinom - HLRCC / Mnohocetná kozní a delozní leiomyomatóza - MCUL.

Hereditary leiomyomatosis and renal cell cancer / multiple cutaneous and uterine leimomyomatosis is a relatively rare autosomal dominant condition which predisposes to the development of cutaneous and uterine leiomyomas and early-onset renal cell carcinoma, typically papillary carcinoma type II. It is caused by germline mutations in the FH gene encoding the fumarate hydratase enzyme. The test of fumarate hydratase activity in lymphocytes may be used as a screening method with subsequent mutation analysis of the FH gene in persons with reduced enzyme activity. Persons with this syndrome should be followed to detect any occurrence of these diseases. Treatment of renal cancer associated with the hereditary leiomyomatosis and renal cell cancer syndrome should be radical with respect to its aggressive nature.

[Genetic counselling in male carriers of BRCA1 and BRCA2 gene mutations]. / Genetické poradenství u muzu nosicu mutací v genech BRCA1 a BRCA2.

BRCA1 and BRCA2 gene mutations cause hereditary breast and ovarian cancer syndrome. The disease has autosomal dominant mode of inheritance, and both genders have the same probability of inheriting the trait. However, the phenotype is different in males and females, and the risk of cancer is significantly lower in males. Although the results of some studies are conflicting, it has been clearly shown that male BRCA mutation carriers are predisposed to an increased risk of breast, prostate, pancreas and stomach cancer when compared to the ge-neral population. With respect to the routinely performed predictive testing of healthy persons in families with BRCA gene mutations, results of these studies are taken into consideration. Screening programs are offered to the patients with the goal of early detection of cancer.