Double heterozygosity for mutations in BRCA1 and BRCA2 in German breast cancer patients: implications on test strategies and clinical management.

Double heterozygosity for disease-causing BRCA1 and BRCA2 mutations is a very rare condition in most populations. Here we describe genetic and clinical data of eight female double heterozygotes (DH) for BRCA1 and BRCA2 mutations found in a cohort of 8162 German breast/ovarian cancer families and compare it with the data of their single heterozygous relatives and of the index patients of the German Consortium for Hereditary Breast and Ovarian Cancer. Furthermore, we analyze the phenotypic features of these patients with respect to age at onset of first cancer, first breast/ovarian cancer and the number of disease manifestations and compare them to that of published Caucasian female DHs and their single heterozygous female relatives. German DHs were not significantly younger at diagnosis of first breast cancer than the single heterozygous index patients of the German Consortium. However, if the data of our study were pooled with that of the literature, DHs were substantially younger at onset of first cancer (mean age 40.4 years, 95 % CI = 36.6-44.1) than their single heterozygous female relatives (mean age 51.9 years, 95 % CI = 46.8-57.0). The two groups also differed concerning the onset of first breast cancer (mean age 40.6 years, 95 % CI = 36.6-44.5 vs. 52.6, 95 % CI = 47.5-57.6). In addition, DHs had a more severe disease than their female relatives carrying a single BRCA mutation (1.4 vs. 0.6 manifestations per person). In contrast to Ashkenazi Jewish females, Caucasian DH females might develop breast cancer at an earlier age and have a more severe disease than single heterozygous BRCA mutation carriers. Therefore, DHs may benefit from more intensive surveillance programs/follow-up care and prophylactic surgery.

Chromosomal mosaicisms in prenatal diagnosis: correlation with first trimester screening and clinical outcome.

OBJECTIVE: To investigate the outcome of pregnancy after detection of chromosomal mosaicism and to determine the correlation between human chorionic gonadotropin (free ß-HCG) and pregnancy-associated plasma protein-A (PAPP-A) levels from first-trimester-screening with pregnancy outcome. METHODS: In a single-center, retrospective survey of the results of prenatal diagnostics performed between January 2000 and March 2011, we identified a total of 40 pregnancies with chromosomal mosaicism. Clinical characteristics and results of first-trimester screening, as well as the outcome of these cases, are described. RESULTS: Out of 40 cases, 21 were defined as confined placental mosaicism, 10 classified as true mosaicism and nine were not classifiable cases. Nuchal translucency (NT) was ≥2.5 mm in 8/30 cases with respective measurements. PAPP-A levels were ≤0.4 MoM in 9/26 cases, with respective measurements, two of them being newborns with growth restriction. Remarkably, in pregnancies of all four children born with severe growth retardation, <3rd percentile PAPP-A levels were below 0.52 MoM. CONCLUSIONS: Our observations show mosaic pregnancy outcomes to be very heterogeneous. Nevertheless, a combination of low PAPP-A and interpretation of chromosomal mosaicism might identify pregnancies at particular risk for fetal growth restriction.

The t(14,15) in mouse strain CBA/CaH-T(14;15)6Ca/J causes a break in the ADAMTS12 gene.

The mouse strain CBA/CaH-T(14;15)6Ca/J carries a homozygous balanced reciprocal translocation between mouse chromosomes 14 and 15, but the break points of this translocation have not previously been examined in detail. Using fluorescent in situ hybridization, we assigned the break point in 14qE3 to a 200-kb region devoid of any known gene. We similarly defined the break point in 15qA1 to a 27-kb region containing involving ADAMTS12. The chromosomal break likely is between exons 2 and 3 of ADAMTS12. This gene encodes a disintegrin and metalloproteinase with thrombospondin motifs, and this product plays crucial roles in both vascularization and cancer progression and has been implicated in the development of arthritis. The CBA/CaH-T(14;15)6Ca/J mouse strain likely is a suitable model for further examination of the influences of defective ADAMTS12 in various pathologic processes.