Is there a correlation between the structure of hair and breast cancer or BRCA1/2 mutations?

It has been suggested that the small angle x-ray scattering (SAXS) pattern of human hair can be used to diagnose breast cancer and possibly to identify BRCA1/2 mutation carriers, who are at significantly elevated risk for developing breast cancer. In particular, the presence of a diffuse ring in the SAXS pattern was said to be diagnostic of either breast cancer or an increased risk thereof. To test this hypothesis, we measured SAXS from the pubic hair of 56 subjects with known BRCA1/2 and breast cancer status. We found that there is no clear association between the pattern of SAXS seen in human pubic hair and the risk of breast cancer or the presence of BRCA1/2 mutations. The possible use of SAXS to diagnose cancer remains conjectural, but this and previous studies do not suggest that SAXS can be used as a reliable method of identifying either BRCA1/2 mutation carriers or women who have had breast cancer.

Prevalence of founder BRCA1 and BRCA2 mutations in unselected French Canadian women with breast cancer.

The frequency of BRCA1 and BRCA2 mutations in women with breast cancer varies according to the age at diagnosis, family history of cancer, and ethnicity/country of origin. We set out to estimate the frequency of seven previously described founder mutations in BRCA1 and BRCA2 in all eligible French Canadian women diagnosed with invasive breast cancer at one Montreal hospital over a 20-month period. One hundred and ninety-two patients were eligible and 127 (66.2%) provided blood for genetic testing. We identified 4 women who carried a founder mutation (3.1%, 95% confidence interval 0.9-7.9%) in this population. Interestingly, all the mutations were in BRCA2. The mean age at diagnosis for mutation carriers was 51.2 years (range 49.1-53.5). Two of these 4 cases were lobular invasive carcinomas and 2 were ductal carcinomas, histological grade 1 or 2. Despite a small tumor size (< or =20 mm), axillary nodal involvement was present in 3 women. Estrogen receptors were strongly expressed in all cases. Two of the 4 cases reported a strong family history of breast cancer, but a family history of site-specific breast cancer was a relatively poor indicator of the presence of BRCA2 mutations. The absence of BRCA1 mutations may be a result of chance, but may also reflect different geographical origins of the most common BRCA1 mutations within the French Canadian population.

Founder BRCA1 and BRCA2 mutations in early-onset French Canadian breast cancer cases unselected for family history.

Recently, founder BRCA1 and BRCA2 mutations were identified in Canadian breast cancer and breast-ovarian cancer families of French ancestry. The presence of a breast cancer case diagnosed at younger than 36 years of age was strongly predictive of the presence of any founder mutation screened. Here we report the occurrence of founder BRCA1 and BRCA2 mutations in a series of 61 French Canadian women with invasive breast cancer diagnosed at age 40 or younger, unselected for family history of breast and ovarian cancer. Germline mutations in BRCA1 (n = 4) and BRCA2 (n = 4) were identified in 8 of 61 (13%) cases. All BRCA1 mutations were found in invasive ductal carcinomas, the most common histologic type of tumor in this series. In contrast, the BRCA2 mutations were found in tumors of various histologic types: two ductal carcinomas, a tumor containing both ductal and lobular histologic types and an invasive lobular carcinoma. Of the 37 women with at least one first-, second- or third-degree relative with breast or ovarian cancer and the 24 women with no history of these cancers, 7 (19%) and 1 (4%), respectively, were mutation carriers. The seven mutation carriers with a family history of cancer had at least one first-, second- or third-degree relative with a breast cancer diagnosis at less than 51 years of age. The identification of founder BRCA1 and BRCA2 mutations in young-onset breast cancer cases unselected for family history can facilitate carrier detection when the expected yield of a comprehensive screen may be low.

Polymorphisms in GSTM1, GSTT1 and CYP1A1 and risk of pancreatic adenocarcinoma.

A prospective study of 149 unselected incident cases of pancreatic adenocarcinoma and 146 ethnically-matched controls found no associations between GSTM1 (adjusted odds ratio (AOR) 1.14), GSTT1 (AOR: 1.19) and CYP1A1 (AOR: 1.08) polymorphisms and pancreatic cancer susceptibility. Smoking and drinking status did not affect results. These polymorphisms do not appear to be important gene modifiers in pancreatic cancer.

Identification of polymorphisms and sequence variants in the human homologue of the mouse natural resistance-associated macrophage protein gene.

The most common mycobacterial disease in humans is tuberculosis, and there is evidence for genetic factors in susceptibility to tuberculosis. In the mouse, the Bcg gene controls macrophage priming for activation and is a major gene for susceptibility to infection with mycobacteria. A candidate gene for Bcg was identified by positional cloning and was designated "natural resistance-associated macrophage protein gene" (Nramp1), and the human homologue (NRAMP1) has recently been cloned. Here we report on (1) the physical mapping of NRAMP1 close to VIL in chromosome region 2q35 by PCR analysis of somatic cell hybrids and YAC cloning and (2) the identification of nine sequence variants in NRAMP1. Of the four variants in the coding region, there were two missense mutations and two silent substitutions. The missense mutations were a conservative alanine-to-valine substitution at codon 318 in exon 9 and an aspartic acid-to-asparagine substitution at codon 543 in the predicted cytoplasmic tail of the NRAMP1 protein. A microsatellite was located in the immediate 5' region of the gene, three variants were in introns, and one variant was located in the 3' UTR. The allele frequencies of each of the nine variants were determined in DNA samples of 60 Caucasians and 20 Asians. In addition, we have physically linked two highly polymorphic microsatellite markers, D2S104 and D2S173, to NRAMP1 on a 1.5-Mb YAC contig. These molecular markers will be useful to assess the role of NRAMP1 is susceptibility to tuberculosis and other macrophage-mediated diseases.

X-linked nephrogenic diabetes insipidus mutations in North America and the Hopewell hypothesis.

In X-linked nephrogenic diabetes insipidus (NDI) the urine of male patients is not concentrated after the administration of the antidiuretic hormone arginine-vasopressin. This disease is due to mutations in the V2 receptor gene that maps to chromosome region Xq28. In 1969, Bode and Crawford suggested that most NDI patients in North America shared common ancestors of Ulster Scot immigrants who arrived in Halifax in 1761 on the ship Hopewell. A link between this family and a large Utah kindred was also suggested. DNA was obtained from 17 affected male patients from the "Hopewell" kindred and from four additional families from Nova Scotia and New Brunswick who shared the same Xq28 NDI haplotype. The Utah kindred and two families (Q2, Q3) from Quebec were also studied. The "Hopewell" mutation, W71X, is a single base substitution (G-->A) that changes codon 71 from TGG (tryptophan) to TGA (stop). The W71X mutation was found in affected members of the Hopewell and of the four satellite families. The W71X mutation is the cause of X-linked NDI for the largest number of related male patients living in North America. Other families (Utah, Q2 and Q3) that are historically and ethnically unrelated bear other mutations in the V2 receptor gene.

Identification of the M1101K mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and complete detection of cystic fibrosis mutations in the Hutterite population.

The Hutterite population is a genetic isolate with an increased incidence of cystic fibrosis (CF). Previously we identified three CF haplotypes defined by polymorphisms flanking the CF transmembrane conductance regulator (CFTR) gene. delta F508 was present on one of the haplotypes in only 35% of CF chromosomes. We hypothesized that the other two CF haplotypes, one of which was the most common and the other of which is rare, each harbored different non-delta F508 mutations. Single-strand conformation polymorphism analysis detected a missense mutation, M1101K, in both chromosomes of a Hutterite patient carrying the two non-delta F508 haplotypes. M1101K appears to have originated on an uncommon CFTR allele and to be infrequent outside the Hutterite population. The presence of M1101K on two haplotypes is likely the result of a CFTR intragenic recombination which occurred since the founding, 10-12 generations ago, of the Hutterite population. The crossover was located between exons 14a and 17b, an interval of approximately 15 kbp. delta F508 and M1101K accounted for all of the CF mutations in patients from 16 CF families representing the three subdivisions of the Hutterite population.