M. F. Niermeijer

Breast cancer after prophylactic bilateral mastectomy in women with a BRCA1 or BRCA2 mutation

BACKGROUND Women with a BRCA1 or BRCA2 mutation have a high risk of breast cancer and may choose to undergo prophylactic bilateral total mastectomy. We investigated the efficacy of this procedure in such women. METHODS We conducted a prospective study of 139 women with a pathogenic BRCA1 or BRCA2 mutation who were enrolled in a breast-cancer surveillance program at the Rotterdam Family Cancer Clinic. At the time of enrollment, none of the women had a history of breast cancer. Seventy-six of these women eventually underwent prophylactic mastectomy, and the other 63 remained under regular surveillance. The effect of mastectomy on the incidence of breast cancer was analyzed by the Cox proportional-hazards method in which mastectomy was modeled as a time-dependent covariate. RESULTS No cases of breast cancer were observed after prophylactic mastectomy after a mean (+/-SE) follow-up of 2.9+/-1.4 years, whereas eight breast cancers developed in women under regular surveillance after a mean follow-up of 3.0+/-1.5 years (P=0.003; hazard ratio, 0; 95 percent confidence interval, 0 to 0.36). The actuarial mean five-year incidence of breast cancer among all women in the surveillance group was 17+/-7 percent. On the basis of an exponential model, the yearly incidence of breast cancer in this group was 2.5 percent. The observed number of breast cancers in the surveillance group was consistent with the expected number (ratio of observed to expected cases, 1.2; 95 percent confidence interval, 0.4 to 3.7; P=0.80). CONCLUSIONS In women with a BRCA1 or BRCA2 mutation, prophylactic bilateral total mastectomy reduces the incidence of breast cancer at three years of follow-up.

LMNA, encoding lamin A/C, is mutated in partial lipodystrophy

The lipodystrophies are a group of disorders characterized by the absence or reduction of subcutaneous adipose tissue. Partial lipodystrophy (PLD; MIM 151660) is an inherited condition in which a regional (trunk and limbs) loss of fat occurs during the peri-pubertal phase. Additionally, variable degrees of resistance to insulin action, together with a hyperlipidaemic state, may occur and simulate the metabolic features commonly associated with predisposition to atherosclerotic disease. The PLD locus has been mapped to chromosome 1q with no evidence of genetic heterogeneity. We, and others, have refined the location to a 5.3-cM interval between markers D1S305 and D1S1600 (refs 5 , 6). Through a positional cloning approach we have identified five different missense mutations in LMNA among ten kindreds and three individuals with PLD. The protein product of LMNA is lamin A/C, which is a component of the nuclear envelope. Heterozygous mutations in LMNA have recently been identified in kindreds with the variant form of muscular dystrophy (MD) known as autosomal dominant Emery-Dreifuss MD (EDMD–AD; ref. 7) and dilated cardiomyopathy and conduction-system disease (CMD1A). As LMNA is ubiquitously expressed, the finding of site-specific amino acid substitutions in PLD, EDMD–AD and CMD1A reveals distinct functional domains of the lamin A/C protein required for the maintenance and integrity of different cell types.

High prevalence of mutations in the microtubule-associated protein tau in a population study of frontotemporal dementia in the Netherlands

Mutations in microtubule-associated protein tau recently have been identified in familial cases of frontotemporal dementia (FTD). We report the frequency of tau mutations in a large population-based study of FTD carried out in the Netherlands from January 1994 to June 1998. Thirty-seven patients had >/=1 first-degree relative with dementia. A mutation in the tau gene was found in 17.8% of the group of patients with FTD and in 43% of patients with FTD who also had a positive family history of FTD. Three distinct missense mutations (G272V, P301L, R406W) accounted for 15.6% of the mutations. These three missense mutations, and a single amino acid deletion (DeltaK280) that was detected in one patient, strongly reduce the ability of tau to promote microtubule assembly. We also found an intronic mutation at position +33 after exon 9, which is likely to affect the alternative splicing of tau. Tau mutations are responsible for a large proportion of familial FTD cases; however, there are also families with FTD in which no mutations in tau have been found, which indicates locus and/or allelic heterogeneity. The different tau mutations may result in disturbances in the interactions of the protein tau with microtubules, resulting in hyperphosphorylation of tau protein, assembly into filaments, and subsequent cell death.

Clinical studies on submicroscopic subtelomeric rearrangements: a checklist

BACKGROUND Submicroscopic subtelomeric chromosome defects have been found in 7.4% of children with moderate to severe mental retardation and in 0.5% of children with mild retardation. Effective clinical preselection is essential because of the technical complexities and cost of screening for subtelomere deletions. METHODS We studied 29 patients with a known subtelomeric defect and assessed clinical variables concerning birth history, facial dysmorphism, congenital malformations, and family history. Controls were 110 children with mental retardation of unknown aetiology with normal G banded karyotype and no detectable submicroscopic subtelomeric abnormalities. RESULTS Prenatal onset of growth retardation was found in 37% compared to 9% of the controls (p<0.0005). A higher percentage of positive family history for mental retardation was reported in the study group than the controls (50%v 21%, p=0.002). Miscarriage(s) were observed in only 8% of the mothers of subtelomeric cases compared to 30% of controls (p=0.028) which was, however, not significant after a Bonferroni correction. Common features (>30%) among subtelomeric deletion cases were microcephaly, short stature, hypertelorism, nasal and ear anomalies, hand anomalies, and cryptorchidism. Two or more facial dysmorphic features were observed in 83% of the subtelomere patients. None of these features was significantly different from the controls. Using the results, a five item checklist was developed which allowed exclusion from further testing in 20% of the mentally retarded children (95% CI 13-28%) in our study without missing any subtelomere cases. As our control group was selected for the “chromosomal phenotype”, the specificity of the checklist is likely to be higher in an unselected group of mentally retarded subjects. CONCLUSIONS Our results suggest that good indicators for subtelomeric defects are prenatal onset of growth retardation and a positive family history for mental retardation. These clinical criteria, in addition to features suggestive of a chromosomal phenotype, resulted in the development of a five item checklist which will improve the diagnostic pick up rate of subtelomeric defects among mentally retarded subjects.

Phenotypic Variation in Hereditary Frontotemporal Dementia with Tau Mutations

Several mutations in the tau gene have been found in families with hereditary frontotemporal dementia and parkinsonism linked to chromosome 17q21‐22 (FTDP‐17). This study is the first attempt to correlate genotype and phenotype in six families with FTDP‐17 with mutations in the tau gene (ΔK280, G272V, P301L, and R406W). We have investigated tau pathology in 1 P301L and 1 R406W patient. The R406W family showed a significantly higher age at onset (59.2 ± 5.5 years) and longer duration of illness (12.7 ± 1.5 years) than the families with the other mutations. The six families showed considerable variation in clinical presentation, but none of them had early parkinsonism. Mutism developed significantly later in the R406W family than in the other families. Frontotemporal atrophy on neuroimaging in the R406W family was less severe than in the P301L and ΔK280 families. The P301L brain contained many pretangles in the frontal and temporal cortex, and the dentate gyrus of hippocampus, showing three tau bands (64, 68, and 72 kd) of extracted tau from the frontal cortex. The presence of many neurofibrillary tangles, many diffuse and classic neuritic plaques in the temporal and parietal cortex, and the hippocampus of the same P301L brain correlated with the presence of four sarkosyl‐insoluble (60, 64, 68, and 72 kd) tau bands. The coexistence of characteristic P301L and Alzheimer pathology in the same brain needs further explanation. The R406W brain showed abundant neurofibrillary tangles in several brain regions, and four tau bands (60, 64, 68, and 72 kd) of extracted tau from these regions. The slower progression of the disease in the R406W family might be explained by the microtubule‐binding properties of the mutant protein.

Screening and Diagnosis for the Fragile X Syndrome among the Mentally Retarded: An Epidemiological and Psychological Survey

The fragile X syndrome is an X-linked mental retardation disorder caused by an expanded CGG repeat in the first exon of the fragile X mental retardation (FMR1) gene. Its frequency, X-linked inheritance, and consequences for relatives all prompt for diagnosis of this disorder on a large scale in all affected individuals. A screening for the fragile X syndrome has been conducted in a representative sample of 3,352 individuals in schools and institutes for the mentally retarded in the southwestern Netherlands, by use of a brief physical examination and the DNA test. The attitudes and reactions of (non)consenting parents/guardians were studied by (pre- and posttest) questionnaires. A total of 2,189 individuals (65%) were eligible for testing, since they had no valid diagnosis, cerebral palsy, or a previous test for the FMR1 gene mutation. Seventy percent (1,531/2,189) of the parents/guardians consented to testing. Besides 32 previously diagnosed fragile X patients, 11 new patients (9 males and 2 females) were diagnosed. Scoring of physical features was effective in preselection, especially for males (sensitivity .91 and specificity .92). Major motives to participate in the screening were the wish to obtain a diagnosis (82%), the hereditary implications (80%), and the support of research into mental retardation (81%). Thirty-four percent of the parents/guardians will seek additional diagnostic workup after exclusion of the fragile X syndrome. The prevalence of the fragile X syndrome was estimated at 1/ 6,045 for males (95% confidence interval 1/9,981-1/ 3,851). On the basis of the actual number of diagnosed cases in the Netherlands, it is estimated that >50% of the fragile X cases are undiagnosed at present.

Familial aggregation in frontotemporal dementia

Objective and background Frontotemporal dementia (FTD) is a common, non-Alzheimers dementia. Its familial occurrence has been reported, but the frequency of positive family history is unknown. Methods We carried out a nationwide genetic-epidemiologic study of FTD in the Dutch population of 15 million people. The family history of dementia was analyzed in 74 FTD patients and 561 age- and gender-matched control subjects. Results We found one or more first-degree relatives with dementia before age 80 in 38% (28 of 74) of FTD patients, but only in 15% (84 of 561) of control subjects. Ten percent of FTD patients had two or more first-degree relatives with dementia compared with 0.9% of the control subjects. Seven percent of FTD patients showed the ApoE4E4 genotype versus 2.3% of the control subjects. The first-degree relatives of FTD had a risk of 22% for dementia before age 80 compared with 11% in relatives of control subjects. The age of onset of dementia in affected first-degree relatives of FTD patients (60.9 ± 10.6 years) was significantly lower than among affected relatives of control subjects (72.3 ± 8.5 years). The first-degree relatives of FTD patients were 3.5 times (95% CI, 2.4 to 5.2) more at risk for developing dementia before age 80 than relatives of control subjects. The hazard ratio in the subgroup with unknown linkage to chromosome 17 was 2.4 (95% CI, 1.5 to 3.7). Conclusion This study documents the importance of genetic factors in a proportion of FTD patients with the age at onset of dementia in first-degree relatives being 11 years earlier than in the general population.

Atypical HNPCC owing to MSH6 germline mutations: analysis of a large Dutch pedigree

Hereditary non-polyposis colorectal cancer (HNPCC) is the most common genetic susceptibility syndrome for colorectal cancer. HNPCC is most frequently caused by germline mutations in the DNA mismatch repair (MMR) genes MSH2 andMLH1. Recently, mutations in another MMR gene, MSH6 (also known asGTBP), have also been shown to result in HNPCC. Preliminary data indicate that the phenotype related toMSH6 mutations may differ from the classical HNPCC caused by defects in MSH2 andMLH1.  Here, we describe an extended Dutch HNPCC family not fulfilling the Amsterdam criteria II and resulting from aMSH6 mutation. Overall, the penetrance of colorectal cancer appears to be significantly decreased (p<0.001) among the MSH6 mutation carriers in this family when compared with MSH2 andMLH1 carriers (32% by the age of 80v >80%).  Endometrial cancer is a frequent manifestation among female carriers (six out of 13 malignant tumours). Transitional cell carcinoma of the urinary tract is also relatively common in both male and female carriers (10% of the carriers).  Moreover, the mean age of onset of both colorectal cancer (MSH6 v MSH2/MLH1 = 55 yearsv 44/41 years) and endometrial carcinomas (MSH6 v MSH2/MLH1 = 55 yearsv 49/48 years) is delayed. As previously reported, we confirm that the pattern of microsatellite instability, in combination with immunohistochemical analysis, can predict the presence of a MSH6 germline defect.  The detailed characterisation of the clinical phenotype of this kindred contributes to the establishment of genotype-phenotype correlations in HNPCC owing to mutations in specific mismatch repair genes.

One Year Follow-Up of Women Opting for Presymptomatic Testing for BRCA1 and BRCA2: Emotional Impact of the Test Outcome and Decisions on Risk Management (Surveillance or Prophylactic Surgery)

Genetic testing enables women at risk for hereditary breast and/or ovarian cancer to find out whether they have inherited the gene mutation (BRCA1/BRCA2), and if so, to opt for frequent surveillance and/or prophylactic surgery (bilateral mastectomy and/or oophorectomy). Here, a follow-up is described for 63 healthy women at 50% risk of being a BRCA1/BRCA2 mutation carrier who underwent genetic testing. The course of distress and problems regarding body image and sexuality up to 1 year after disclosure of the test-outcome were described separately for mutation carriers undergoing mastectomy (n = 14), for mutation carriers opting for surveillance (n = 12) and for non-mutation carriers (n = 37). Furthermore, we analyzed whether women opting for prophylactic mastectomy differed from those opting for close surveillance with respect to biographical characteristics, experiences with cancer in relatives and personality. Women opting for prophylactic mastectomy had significantly higher distress levels than mutation carriers who opted for surveillance, and the non-mutation carriers. This difference in levels of distress was highest at pre- and post-test and had almost disappeared at 1-year follow-up. Besides, mutation carriers opting for prophylactic mastectomy were more often in their thirties, more often had young children and had a longer awareness of the genetic nature of cancer in the family than those opting for regular surveillance. Adverse effects were observed in women who underwent prophylactic mastectomy (mostly in combination with immediate breast reconstruction) regarding the perception of how their breast region looked like and felt, the intimate relationship and physical wellbeing whereas women opting for prophylactic mastectomy reported more distress than the other women in the study, their distress levels had significantly decreased 6 months or longer after surgery, possibly due to the significant risk reduction of developing breast cancer. This might explain, why most women who underwent prophylactic mastectomy were satisfied with this decision, despite a perceived negative impact on body image, the intimate relationship and physical wellbeing.

Caregiver Burden, Health-Related Quality of Life and Coping in Dementia Caregivers: A Comparison of Frontotemporal Dementia and Alzheimer’s Disease

Frontotemporal dementia (FTD) is the second most prevalent dementia after Alzheimer’s disease (AD). We compared 29 FTD and 90 AD caregivers with respect to burden, health-related quality of life (HQoL) and coping. FTD caregivers were more burdened than AD caregivers, and caregivers of patients who were demented for shorter duration had lower HQoL. We furthermore compared the 29 FTD caregivers with 34 caregivers of institutionalized FTD patients to understand their specific caregiver issues. Caregivers of FTD patients institutionalized after shorter dementia duration were most burdened and affected in their HQoL. Overall, passive coping strategies were associated with increased burden and decreased HQoL. We recommend that FTD caregivers be offered more support than AD caregivers. Furthermore, we suggest that interventions target passive coping strategies.