Exclusion of large deletions and other rearrangements in BRCA1 and BRCA2 in Finnish breast and ovarian cancer families.

In the Finnish population, identified mutations in BRCA1 and BRCA2 account for a less than expected proportion of hereditary breast and ovarian cancer. All previous studies performed in our country have concentrated on finding germ-line mutations in the coding and splice-site regions of these two genes. Therefore, we wanted to use a different methodological approach and search for large genomic rearrangements, to exclude the possibility of biased BRCA1 and BRCA2 mutation spectra due to known limitations of the previously used PCR-based detection methods. Our results support earlier notions that other genes than BRCA1 and BRCA2 will explain a majority of the still unexplained cases of hereditary susceptibility to breast and ovarian cancer.

The mutation spectrum of the EDA gene in X-linked anhidrotic ectodermal dysplasia.

Mutations in ectodysplasin, the protein product of the EDA or ED1 gene, cause X-linked anhidrotic ectodermal dysplasia. From sixteen families we have identified thirteen mutations, of which nine were novel: a deletion of the entire exon 1, altered splicing site in intron 7 (IVS-2A-->G) and in intron 9 (IVS9+8 C-->G), deletion of 8 bp (1967-1974 nt), four missense mutations (G255C, G255D, W274G, C332Y) and nonsense mutation W274X. Previously identified and the novel mutations form four clusters: 1) at the junction of the transmembrane and extracellular domains, 2) at a putative protease recognition site, possibly affecting cleavage of ectodysplasin, 3) at the trimerizing collagen-like domain, and 4) at regions of high homology to tumor necrosis factor domains. Truncating and splice site mutations occur within the proximal two-thirds of the protein. Our data suggest the functional importance of specific ectodysplasin domains. Hum Mutat 17:349, 2001.

Involvement of BRCA1 and BRCA2 in breast cancer in a western Finnish sub-population.

To date, two major familial breast cancer predisposition genes, BRCA1 and BRCA2, have been identified with hundreds of germ-line mutations, accounting for 5--10% of all breast cancer and 40--60% of all inherited breast cancer. Unexpectedly elevated incidence of breast cancer, especially in the older age classes, was observed in a Western Finnish region representing a relatively homogeneous population. This study was designed to test the hypothesis that there are inherited BRCA1 or BRCA2 mutations, which confer variable and/or age-dependent penetrance on carriers. Expecting a founder effect, we searched for geographical clustering of breast cancer cases and searched for associations between the affected phenotype and shared genomic segments in the BRCA1 and BRCA2 genomic regions. Our haplotype association study did not reveal any founder effects for either BRCA1 or BRCA2. However, there were two mutations prevalent in this geographical area with minor founder effects, BRCA2 T8555G and 999del5. This is one of the few geographically ascertained, population-based studies that indicate an overall frequency of BRCA1 and BRCA2 mutations at about 2--3% in all breast cancer cases. The geographical clustering of breast cancer cases was not explained by BRCA1 or BRCA2 genes.

Stromelysin-2 is upregulated during normal wound repair and is induced by cytokines.

Stromelysin-2 is a matrix metalloproteinase that degrades in vitro several protein components relevant to wound repair such as collagens III and IV, gelatin, nidogen, laminin-1, proteoglycans, and elastin. Furthermore, it can activate other matrix metalloproteinases, such as collagenase-1 (matrix metalloproteinase-1) and collagenase-2 (matrix metalloproteinase-8), as well as 92 kDa gelatinase. The aim of this study was to determine in a large variety of wounds (normally healing dermal and mucosal wounds, suction blisters, ex vivo cultures, diabetic, decubitus, rheumatic, and venous ulcers) and keratinocyte cultures, which factors contribute to stromelysin-2 expression and how it is induced in relation to other matrix metalloproteinases. Our results show that stromelysin-2 mRNA and protein are upregulated later (at 3 d) than matrix metalloproteinase-1 in normally healing wounds and ex vivo explants, in which stromelysin-2 is invariably expressed by keratinocytes migrating over dermal matrix. The number of keratinocytes expressing stromelysin-2 was greatest in chronic inflamed diabetic and venous ulcers compared with rheumatoid and decubitus ulcers, six of which had no signal. In keratinocyte cultures, tumor necrosis factor-alpha, epidermal growth factor, and transforming growth factor-beta1 induced stromelysin-2 expression as measured by quantitative reverse transcriptase-polymerase chain reaction, whereas different matrices did not upregulate the mRNA. Immunostaining demonstrated stromal transforming growth factor-beta1 in contact with the stromelysin-2-positive keratinocytes. Our results suggest that stromelysin-2 expression is important for the normal repair process and is upregulated by cytokines rather than cell-matrix interactions. Stromelysin-2 is most likely to participate in the remodeling of the newly formed basement membrane, and is not overexpressed in retarded wound healing.

Multiple founder effects and geographical clustering of BRCA1 and BRCA2 families in Finland.

In the Finnish breast and ovarian cancer families six BRCA1 and five BRCA2 mutations have been found recurrently. Some of these recurrent mutations have also been seen elsewhere in the world, while others are exclusively of Finnish origin. A haplotype analysis of 26 Finnish families carrying a BRCA1 mutation and 20 families with a BRCA2 mutation indicated that the carriers of each recurrent mutation have common ancestors. The common ancestors were estimated to trace back to 7-36 generations (150-800 years). The time estimates and the geographical clustering of these founder mutations in Finland are in concordance with the population history of this country. Analysis of the cancer phenotypes showed differential ovarian cancer expression in families carrying mutations in the 5' and 3' ends of the BRCA1 gene, and earlier age of ovarian cancer onset in families with BRCA1 mutations compared with families with BRCA2 mutations. The identification of prominent and regional BRCA1 and BRCA2 founder mutations in Finland will have significant impact on diagnostics in Finnish breast and ovarian cancer families. An isolated population with known history and multiple local founder effects in multigenic disease may offer distinct advantages also for mapping novel predisposing genes.

Conformations of the regulatory domain of cardiac troponin C examined by residual dipolar couplings.

Conformations of the regulatory domain of cardiac troponin C (cNTnC) were studied by means of residual dipolar couplings measured from samples dissolved in dilute liquid crystals. Changes in the main chain HN residual dipolar couplings revealed a conformational change in cNTnC due to the complexation with the second binding region (amino acids 148-163) of cardiac troponin I (cTnI). Formation of the complex is accompanied with a molecular realignment in the liquid crystal. The residual dipolar couplings measured for apo-cNTnC and the complex with TnI were in agreement with the values computed from the corresponding closed and open solution structures, whereas for the calcium-loaded conformation the correlation and quality factor were only modest. Ca2+-cNTnC may be subject to conformational exchange. The data support the model that cardiac troponin C functions as a calcium-dependent open-closed switch, such as the skeletal troponin C.

Clinical findings in mosaic carriers of hypohidrotic ectodermal dysplasia.

BACKGROUND: Hypohidrotic ectodermal dysplasia (HED) is a severe developmental disorder in which nonallelic genetic heterogeneity has been demonstrated. Even though X-linked and autosomal recessive forms are phenotypically similar, identification of the way of transmission is mandatory to give reliable genetic counseling to the family and to address molecular studies. Complete examination of relatives of patients with HED and identification of carriers of partial forms of the disorder in their families is the key to clarifying intrafamilial genetic transmission. OBSERVATIONS: Seven patients diagnosed as having HED and their first-degree relatives were carefully examined and tested with starch-iodine. Useful signs for identifying possible carriers of and postzygotic mosaics for X-linked HED and for finding distinctive features between the X-linked and the autosomal recessive forms of the disorder were recorded. Of these, the most striking finding was the clinical evidence of the distribution of normal and abnormal skin along Blaschko lines in heterozygous and postzygotic mutation carriers of X-linked HED. Six heterozygous female carriers of X-linked HED, 2 males with postzygotic mutations for X-linked HED, and 1 female with autosomal recessive HED were clinically identified. At the end, 6 families had a diagnosis of X-linked HED, while 1 had a diagnosis ofautosomal recessive HED. Clinical data, family history, and starch-iodine test results were never in conflict in the 7 families. CONCLUSIONS: Careful clinical examination is the best way to detect heterozygous carriers and postzygotic mutation of X-linked HED. Heterozygous parents of patients with autosomal recessive HED show no features of the disorder. The starch-iodine test is not superior to a clinical examination in heterozygous carrier detection but may play a confirmative role and be of help in differentiating X-linked and autosomal recessive HED in isolated patients.

Mutation analysis of BRCA1 and BRCA2 in Turkish cancer families: a novel mutation BRCA2 3414del4 found in male breast cancer.

Since the identification of the BRCA1 and BRCA2 breast-ovarian cancer susceptibility genes, mutation analyses have been carried out in different populations. Here we screened 15 Turkish breast and breast-ovarian cancer families for mutations in both genes by conformation-sensitive gel electrophoresis (CSGE) and the protein truncation test (PTT), followed by DNA sequencing. Three families included a male breast cancer case, one without family history. Three germline mutations were identified, two in BRCA1 and one in BRCA2. The two BRCA1 mutations, 5382insC and 5622C-->T, were found in breast-ovarian cancer families. The BRCA2 3414delTCAG is a novel mutation detected in a site-specific breast cancer family that included 1 case of male breast cancer. These first results of Turkish families show that the frequency of germline BRCA1 or BRCA2 mutations appears to be high in families with at least 3 breast and/or ovarian cancer cases.

Germ-line TP53 mutations in Finnish cancer families exhibiting features of the Li-Fraumeni syndrome and negative for BRCA1 and BRCA2.

Mutations in BRCA1 and BRCA2 account for a large portion of the inherited predisposition to breast and ovarian cancer. It was recently discovered that mutations in these two genes are less common in the Finnish population than expected. Because the genetic background of breast cancer, in particular, is largely obscure, it became necessary to search for mutations in other susceptibility genes. Because seven of our BRCA1 and BRCA2 mutation-negative families fulfilled the criteria of either Li-Fraumeni syndrome (LFS) or Li-Fraumeni-like syndrome (LFL), we decided to screen them for germ-line TP53 mutations in exons 5-8 using a dual-temperature single-strand conformation polymorphism assay (SSCP). Two missense mutations (Asn235Ser and Tyr220Cys) were identified. The clinical significance of these findings was evaluated by comparison to previously reported germ-line TP53 mutation data, and by using the tumor loss of heterozygosity (LOH) analysis. In addition, an immunohistochemical analysis of tumor specimens from mutation-positive individuals was performed. Our results suggest that the observed missense mutations confer susceptibility to cancer, and that germ-line TP53 mutations would therefore explain an additional fraction of hereditary breast cancer in Finland.

Solution structure and main chain dynamics of the regulatory domain (Residues 1-91) of human cardiac troponin C.

The three-dimensional structure of calcium-loaded regulatory, i.e. N-terminal, domain (1-91) of human cardiac troponin C (cNTnC) was determined by NMR in water/trifluoroethanol (91:9 v/v) solution. The single-calcium-loaded cardiac regulatory domain is in a "closed" conformation with comparatively little exposed hydrophobic surface. Difference distance matrices computed from the families of Ca2+-cNTnC, the apo and two-calcium forms of the skeletal TnC (sNTnC) structures reveal similar relative orientations for the N, A, and D helices. The B and C helices are closer to the NAD framework in Ca2+-cNTnC and in apo-sNTnC than in 2.Ca2+-sNTnC. However, there is an indication of a conformational exchange based on broad 15N resonances for several amino acids measured at several temperatures. A majority of the amides in the alpha-helices and in the calcium binding loop exhibit very fast motions with comparatively small amplitudes according to the Lipari-Szabo model. A few residues at the N and C termini are flexible. Data were recorded from nonlabeled and 15N-labeled samples, and backbone dynamics was investigated by 15N T1, T2, and heteronuclear nuclear Overhauser effect as well as by relaxation interference measurements.