It has been suggested that chromosome instability is a constitutional factor which may be characteristic of families with an increased risk for the development of malignancies. In this study spontaneous chromosome aberrations, sister chromatid exchanges (SCEs) and chromosome sensitivity to bleomycin were analysed in cultured lymphocytes from 13 families with sporadic non-hereditary unilateral retinoblastoma patients. The significantly increased chromosome instability was detected only by the bleomycin test. Higher mean values of breaks/cell were found in all groups of relatives: patients, parents and siblings.
Rb-1 gene promoter mutations are very rare events, only three retinoblastoma families with such alterations were reported up to now. Herein, we describe the first case of the Rb-1 gene promoter germ, line de novo mutation in a proband with sporadic unilateral retinoblastoma. All of reported Rb-1 gene promoter mutations are associated with a reduced penetrance. Together with the literature data it can be roughly estimated that penetration of cases with alteration localised in promoter and similar as in presented case, is at the level of about 60-70%. It seems, that there are some promoter sites more prone for occurrence of mutations.
The study aimed to determine whether hereditary ovarian cancers that are not caused by BRCA1/BRCA2 constitutional mutations are associated with a predisposition to cystadenoma. The study consisted of two parts. Part one concerned the incidence of ovarian cystadenoma in females from families with hereditary ovarian cancer unassociated with BRCA1 mutations. The study group included 62 female patients from 29 families, without any previously diagnosed malignancy, with no proven constitutional mutation of the BRCA1 gene. The first control group was composed of 62 female patients from 53 families, without any previously diagnosed malignancy, with an identified constitutional mutation of the BRCA1 gene. The second control group comprised 124 female patients for whom the only reason for the examination was a prophylactic check-up. All studied women were subjected to intravaginal ultra- sonographic investigations. In 8 patients with benign and/or borderline ovarian cystadenoma, a complete sequencing of coding fragments of the BRCA2 gene from the peripheral blood DNA was performed. Part two of this study concerned the incidence and pattern of malignant tumors in the families of female patients with ovarian cystadenoma. The final study group included 117 patients who had 726 I0 relatives (359 females and 367 males). We concluded that cystadenoma is likely to be a characteristic feature of the subgroup of families with hereditary ovarian cancers unassociated with BRCA1/BRCA2 constitutional mutations.
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