Monica Emanuelsson

Genetic analysis of the RNASEL gene in hereditary, familial, and sporadic prostate cancer

Purpose: The RNASEL gene has been proposed as a candidate gene for the HPC1 locus through a positional cloning and candidate gene approach. Cosegregation between the truncating mutation E265X and disease in a hereditary prostate cancer (HPC) family and association between prostate cancer risk and the common missense variant R462Q has been reported. To additionally evaluate the possible role of RNASEL in susceptibility to prostate cancer risk, we performed a comprehensive genetic analysis of sequence variants in RNASEL in the Swedish population. Experimental Design: Using 1624 prostate cancer cases and 801 unaffected controls, the truncating mutation E265X and five common sequence variants, including the two missense mutations R462Q and D541E, were evaluated for association between genotypes/haplotypes and prostate cancer risk. Results: The prevalence of E265X carriers among unaffected controls and prostate cancer patients was almost identical (1.9 and 1.8% in controls and cases, respectively), and evidence for segregation of E265X with disease was not observed within any HPC family. Overall, the analyses of common sequence variants provided limited evidence for association with prostate cancer risk. We found a marginally significant inverse association between the missense mutation D541E and sporadic prostate cancer risk (odds ratio, 0.77; 95% confidence interval, 0.59–1.00) and reduced risk of prostate cancer in carriers of two different haplotypes being completely discordant. Conclusions: Considering the high quality in genotyping and the size of this study, these results provide solid evidence against a major role of RNASEL in prostate cancer etiology in Sweden.

Mutation analysis of the MLH1, MSH2 and MSH6 genes in patients with double primary cancers of the colorectum and the endometrium: a population-based study in northern Sweden.

Hereditary nonpolyposis colorectal cancer (HNPCC) is an autosomal dominant disorder that predisposes to predominantly colorectal and endometrial cancers due to germline mutations in DNA mismatch repair genes, mainly MLH1, MSH2 and in families with excess endometrial cancer also MSH6. In this population‐based study, we analysed the mutation spectrum of the MLH1, MSH2 and MSH6 genes in a cohort of patients with microsatellite unstable double primary tumours of the colorectum and the endometrium by PCR, DHPLC and sequencing. Fourteen of the 23 patients (61%) had sequence variants in MLH1, MSH2 or MSH6 that likely affect the protein function. A majority (10/14) of the mutations was found among probands diagnosed before age 50. Five of the mutations (36%) were located in MLH1, 3 (21%) in MSH2 and 6 (43%) in MSH6. MSH6 seem to have larger impact in our population than in other populations, due to a founder effect since all of the MSH6 families originate from the same geographical area. MSH6 mutation carriers have later age of onset of both colorectal cancer (62 vs. 51 years) and endometrial cancer (58 vs. 48 years) and a larger proportion of endometrial cancer than MLH1 or MSH2 mutation carriers. We can conclude that patients with microsatellite unstable double primary cancers of the colorectum and the endometrium have a very high risk of carrying a mutation not only in MLH1 or MSH2 but also in MSH6, especially if they get their first cancer diagnosis before the age of 50.

Two Swedish founder MSH6 mutations, one nonsense and one missense, conferring high cumulative risk of Lynch syndrome.

Lynch syndrome, or hereditary non‐polyposis colorectal cancer (HNPCC), is a cancer susceptibility syndrome caused by germline mutations in mismatch‐repair genes, predominantly MLH1, MSH2 and MSH6. A majority of the mutations reported are truncating, but for MSH6, missense mutations constitute over one third. Few have been proven pathogenic in functional studies or shown to segregate in families. In this study, we show segregation of the putative pathogenic MSH6 missense mutation c.1346T>C p.Leu449Pro with microsatellite instability‐high Lynch syndrome‐related tumours lacking MSH6 expression in a large 17th century pedigree. Another large family with the MSH6 nonsense c.2931C>G, p.Tyr977X mutation is similar in tumour spectra, age of onset and cumulative risk. These MSH6 families, despite their late age of onset, have a high lifetime risk of all Lynch syndrome‐related cancers, significantly higher in women (89% by age 80) than in men (69%). The gender differences are in part explained by high endometrial (70%) and ovarian (33%) cancer risks added upon the high colorectal cancer risk (60%). The several occurrences of breast cancer are not due to the MSH6 mutations. These findings are of great importance for counselling, management and surveillance of families with MSH6 mutations.

Women with Saethre-Chotzen syndrome are at increased risk of breast cancer

The Saethre‐Chotzen syndrome is an autosomal, dominantly inherited craniosynostosis caused by mutations in the basic helix‐loop‐helix transcription factor gene TWIST1. This syndrome has hitherto not been associated with an increased risk of cancer. However, recent studies, using a murine breast tumor model, have shown that Twist may act as a key regulator of metastasis and that the gene is overexpressed in subsets of sporadic human breast cancers. Here, we report a novel association between the Saethre‐Chotzen syndrome and breast cancer. In 15 Swedish Saethre‐Chotzen families, 15 of 29 (52%) women carriers over the age of 25 had developed breast cancer. At least four patients developed breast cancer before 40 years of age, and five between 40 and 50 years of age. The observed cases with breast cancer (n = 15) are significantly higher than expected (n = 0.89), which gives a standardized incidence ratio (SIR) of 16.80 (95% CI 1.54–32.06). Our finding of a high frequency of breast cancer in women with the Saethre‐Chotzen syndrome identifies breast cancer as an important and previously unrecognized symptom characteristic of this syndrome. The results strongly suggest that women carriers of this syndrome would benefit from genetic counseling and enrolment in surveillance programs including yearly mammography. Our results also indicate that the TWIST1 gene may be a novel breast cancer susceptibility gene. Additional studies are, however, necessary to reveal the mechanism by which TWIST1 may predispose to early onset breast cancer in Saethre‐Chotzen patients.

BRCA2 mutation in a family with hereditary prostate cancer

Hereditary prostate cancer is a genetically heterogeneous disease, and so far four different susceptibility loci have been identified. Reports of associated cancers are few, and it is generally considered a site‐specific disease. However, some reports have shown an elevated risk for prostate cancer among BRCA2 mutation carriers. In this report, we present a family in which the father and four of his sons were diagnosed with prostate cancer at exceptionally early ages (51, 52, 56, 58, and 63 years, respectively). In addition, three daughters were diagnosed with breast cancer between the ages of 47 and 61. In this family, a truncating mutation in exon 11, 6051delA of the BRCA2 gene, leading to an early termination of the protein (codon 1962), was identified. Although BRCA2 is probably responsible only for a very small fraction of hereditary prostate cancers, this finding supports previous reports of an increased risk of prostate cancer in BRCA2 mutation carriers.

A population based cohort study of patients with multiple colon and endometrial cancer : Correlation of microsatellite instability (MSI) status, age at diagnosis and cancer risk

Hereditary non‐polyposis colorectal cancer, HNPCC, is an autosomal dominant condition predisposing to cancers of primarily the colorectum and the endometrium. The aim of our study was to identify persons at a high risk of hereditary colorectal cancer and to estimate their risk of colon and other HNPCC‐associated tumours. Family histories of cancer were obtained on 89 persons with double primary (DP) cancers of the colon and the endometrium. The cancer risks in their 649 first‐degree‐relatives (FDR) were analysed. The microsatellite instability (MSI) status of the tumour of the proband was also analysed and the cancer risks were estimated in relation to MSI status and age at diagnosis in the proband (over or under 50 years). The overall standardised incidence ratio (SIR) was 1.69 (95% CI; 1.39–2.03). In the =50‐year‐old cohort the SIR was 2.67 (95% CI; 2.08–3.38). Colon, rectal and uterus cancer exhibited significantly increased risks. This risk was further increased in the =50‐year‐old MSI positive families. Several =50‐year‐old MSI negative HNPCC‐like families with increased risks were also identified. In conclusion a FDR to a person with a DP cancer of the colorectum or the colon/endometrium have a significantly increased risk of having a colorectal or other HNPCC‐associated cancers if the proband is diagnosed with one of the cancers before age 50. These families are candidates for genetic counselling and colorectal screening programmes. Mutations in mismatch repair genes can explain some of the increased risk in these families, but mutations in MSI negative families are probably due to other colon cancer susceptibility genes not yet described.

Genome-wide linkage analysis of 1,233 prostate cancer pedigrees from the International Consortium for prostate cancer Genetics using novel sumLINK and sumLOD analyses

Prostate cancer (PC) is generally believed to have a strong inherited component, but the search for susceptibility genes has been hindered by the effects of genetic heterogeneity. The recently developed sumLINK and sumLOD statistics are powerful tools for linkage analysis in the presence of heterogeneity.

Low frequency of allelic imbalance at the prostate cancer susceptibility loci HPC1 and 1p36 in Swedish men with hereditary prostate cancer.

The aim of this study was to investigate allelic imbalance at the major human prostate cancer susceptibility locus HPC1 at 1q24–25 and the recently reported, putative, susceptibility locus at 1p36 in prostate tumors from Swedish families with hereditary prostate cancer. We analyzed 31 prostate tumors and two lymph node metastases from 33 Swedish men in 22 families with hereditary prostate cancer for the presence of allelic imbalance using microsatellite markers D1S158, D1S422, and D1S238 for the HPC1 locus and D1S1597, D1S407, and D1S489 for the 1p36 locus. Frequencies of allelic imbalance at the two investigated loci were quite low, 3 of 27 informative tumors at the 1p36 locus and 3 of 27 informative tumors at the HPC1 locus. Interestingly, two tumors showed allelic imbalance at both loci investigated, suggesting that they may have lost a great part of chromosome 1. Taking this possibility into consideration, the specific loss of the two investigated loci may be even lower (1 of 27 informative tumors for either locus). The very low level of allelic imbalance found at HPC1 and 1p36 makes it unlikely that these loci encode genes that are acting as classic tumor suppressor genes in the initiation or progression of hereditary prostate cancer. Of the eight tumors from HPC1‐linked families, only two showed AI at the HPC1 locus, one of which had lost the wild‐type allele.

Psychological aspects of screening in families with hereditary prostate cancer

Objective: Approximately 5-10% of prostate cancer cases are caused by dominantly inherited susceptibility to the disease. Although advances have been made in research concerning the genetic mechanisms of hereditary prostate cancer, little is known about the psychological consequences. The aim of this study was to assess possible negative psychological effects of screening for prostate cancer in a high-risk population. Material and Methods: This study was based on a previous study of risk perception, screening practice and interest in genetic testing among unaffected men in families with hereditary prostate cancer. The present study included 87 men from the previous study who were screened regularly for prostate cancer. Of these, 74 men agreed to receive two further questionnaires, both of which included the Hospital Anxiety and Depression Scale (HAD) and the Impact of Event Scale (IES), one of which was filled in on the day of the next screening visit and the other 4-6 weeks later. Results: The response rate was 77% (57/74). There were no statistically significant differences in total or subscale HAD or IES scores between the two points of measurement. There was a trend towards slightly higher HAD scores on the day of the screening visit, but the difference was so small that we did not consider it clinically relevant. In an attempt to identify risk factors for a negative impact of screening several subgroup analyses were performed, but none of these subgroups had significantly higher scores on the day of the visit than afterwards. Conclusion: Most men with a high hereditary risk of developing prostate cancer do not experience severe psychological adverse effects resulting from attendance for screening.

Chromosomes 4 and 8 implicated in a genome wide SNP linkage scan of 762 prostate cancer families collected by the ICPCG.

In spite of intensive efforts, understanding of the genetic aspects of familial prostate cancer (PC) remains largely incomplete. In a previous microsatellite‐based linkage scan of 1,233 PC families, we identified suggestive evidence for linkage (i.e., LOD ≥ 1.86) at 5q12, 15q11, 17q21, 22q12, and two loci on 8p, with additional regions implicated in subsets of families defined by age at diagnosis, disease aggressiveness, or number of affected members.