A. van den Ouweland

Survival and tumour characteristics of breast-cancer patients with germline mutations of BRCA1

BACKGROUND Hereditary breast cancer has been associated with mutations in the BRCA1 and BRCA2 genes and has a natural history different from sporadic breast cancer. We investigated disease-free and overall survival for patients with a proven BRCA1 alteration. METHODS We estimated disease-free and overall survival for 49 Dutch patients from 19 consecutive families with a proven specific BRCA1 mutation and one family with strong evidence for linkage to the BRCA1 gene. We compared clinical outcome and data on tumour size, histology, axillary nodal status, contralateral breast cancer, and oestrogen-receptor and progesterone-receptor status with those of 196 patients with sporadic breast cancer, matched for age and year of diagnosis. FINDINGS Disease-free survival for BRCA1 and sporadic patients at 5 years was 49% (95% CI 33-64) and 51% (43-59), respectively (p=0.98). Overall survival at 5 years was 63% (47-76) and 69% (62-76), respectively (p=0.88). Recurrence and death rates did not differ significantly between groups. Hazard ratios for recurrence and death among BRCA1 patients were 1.00 (0.65-1.55) and 1.04 (0.63-1.71) relative to sporadic patients (p=0.88), and these did not differ significantly after adjustment for prognostic factors. Patients with BRCA1-associated breast cancer had twice as many progesterone-receptor-negative tumours (p<0.005) and development of contralateral breast cancer was four to five times as frequent as in the sporadic group (p<0.001). INTERPRETATION We showed that disease-free and overall survival were similar for sporadic and hereditary breast cancer in the presence of different tumour characteristics, which has implications for screening prophylactic therapy, and different treatments of hereditary breast cancer.

SURVIVAL AND TUMOUR CHARACTERISTICS OF BREAST-CANCER PATIENTS WITH GERMLINE MUTATIONS OF BRCA1

Summary Background Hereditary breast cancer has been associated with mutations in the BRCA1 and BRCA2 genes and has a natural history different from sporadic breast cancer. We investigated disease-free and overall survival for patients with a proven BRCA1 alteration. Methods We estimated disease-free and overall survival for 49 Dutch patients from 19 consecutive families with a proven specific BRCA1 mutation and one family with strong evidence for linkage to the BRCA1 gene. We compared clinical outcome and data on tumour size, histology, axillary nodal status, contralateral breast cancer, and oestrogen-receptor and progesterone-receptor status with those of 196 patients with sporadic breast cancer, matched for age and year of diagnosis. Findings Disease-free survival for BRCA1 and sporadic patients at 5 years was 49% (95% CI 33–64) and 51% (43–59), respectively (p=0·98). Overall survival at 5 years was 63% (47–76) and 69% (62–76), respectively (p=0·88). Recurrence and death rates did not differ significantly between groups. Hazard ratios for recurrence and death among BRCA1 patients were 1·00 (0·65–1·55) and 1·04 (0·63–1·71) relative to sporadic patients (p=0·88), and these did not differ significantly after adjustment for prognostic factors. Patients with BRCA1-associated breast cancer had twice as many progesterone-receptor-negative tumours (p<0·005) and development of contralateral

Effectiveness of Breast Cancer Surveillance in BRCA1/2 Gene Mutation Carriers and Women With High Familial Risk

PURPOSE Women with a high breast cancer risk due to a familial predisposition may choose between preventive surgery and regular surveillance. The effectiveness of surveillance in high-risk women and especially BRCA1/2 mutation carriers is unknown. We present first results from a single large family cancer clinic. PATIENTS AND METHODS Women with breast cancer risk over 15% were examined by physical examination every 6 months and mammography every year. Detection rates and screening parameters were calculated for the total group and separately for different age and genetic risk groups. RESULTS At least one examination was performed in 1,198 women: 449 moderate and 621 high-risk women and 128 BRCA1/2 mutation carriers. Within a median follow-up of 3 years, 35 breast cancers were detected (four ductal carcinoma-in-situ; 31 invasive tumors); the average detection rate was 9.7 per 1,000. Detection rates (95% confidence interval) for moderate and high-risk women and BRCA1/2 carriers were 3.3 (1.1 to 8.6), 8.4 (5.4 to 13.2), and 33 (17 to 63) per 1,000 person-years, respectively. The ratio of observed cases versus breast cancers expected in an average-risk population of comparable age was 2.7, 7.0 and 23.7 respectively. Overall, node negativity was 65%; 34% of primary tumors were less than 10 mm; sensitivity was 74%. Results with respect to tumor stage and sensitivity were less favorable in BRCA1/2 carriers and in women under the age of 40. CONCLUSION It is possible to identify young women at high risk for breast cancer. The number of cancers detected was significantly greater than expected in an age-matched average-risk population and related to the risk category. Overall, screening parameters were comparable to population screening data, with less favorable results in the youngest age group (< 40) and BRCA1/2 carriers.

Rapid antibody test for fragile X syndrome

Fragile X syndrome is the most common known cause of inherited mental retardation. Identification of patients and carriers of fragile X syndrome is usually done with a DNA test system but we have developed a rapid antibody to identify fragile X patients. This non-invasive test requires only 1 or 2 drops of blood and can be used for screening large groups of mentally retarded people and neonates for fragile X syndrome.

Sporadic Imprinting Defects in Prader-Willi Syndrome and Angelman Syndrome: Implications for Imprint-Switch Models, Genetic Counseling, and Prenatal Diagnosis

The Prader-Willi syndrome (PWS) and the Angelman syndrome (AS) are caused by the loss of function of imprinted genes in proximal 15q. In approximately 2%-4% of patients, this loss of function is due to an imprinting defect. In some cases, the imprinting defect is the result of a parental imprint-switch failure caused by a microdeletion of the imprinting center (IC). Here we describe the molecular analysis of 13 PWS patients and 17 AS patients who have an imprinting defect but no IC deletion. Heteroduplex and partial sequence analysis did not reveal any point mutations of the known IC elements, either. Interestingly, all of these patients represent sporadic cases, and some share the paternal (PWS) or the maternal (AS) 15q11-q13 haplotype with an unaffected sib. In each of five PWS patients informative for the grandparental origin of the incorrectly imprinted chromosome region and four cases described elsewhere, the maternally imprinted paternal chromosome region was inherited from the paternal grandmother. This suggests that the grandmaternal imprint was not erased in the fathers germ line. In seven informative AS patients reported here and in three previously reported patients, the paternally imprinted maternal chromosome region was inherited from either the maternal grandfather or the maternal grandmother. The latter finding is not compatible with an imprint-switch failure, but it suggests that a paternal imprint developed either in the maternal germ line or postzygotically. We conclude (1) that the incorrect imprint in non-IC-deletion cases is the result of a spontaneous prezygotic or postzygotic error, (2) that these cases have a low recurrence risk, and (3) that the paternal imprint may be the default imprint.

Cognitive impairment in tuberous sclerosis complex is a multifactorial condition

Objective: In patients with tuberous sclerosis complex (TSC), associations between tuber number, infantile spasms, and cognitive impairment have been proposed. We hypothesized that the tuber/brain proportion (TBP), the proportion of the total brain volume occupied by tubers, would be a better determinant of seizures and cognitive function than the number of tubers. We investigated tuber load, seizures, and cognitive function and their relationships. Methods: Tuber number and TBP were characterized on three-dimensional fluid-attenuated inversion recovery MRI with an automated tuber segmentation program. Seizure histories and EEG recordings were obtained. Intelligence equivalents were determined and an individual cognition index (a marker of cognition that incorporated multiple cognitive domains) was calculated. Results: In our sample of 61 patients with TSC, TBP was inversely related to the age at seizure onset and to the intelligence equivalent and tended to be inversely related to the cognition index. Further, a younger age at seizure onset or a history of infantile spasms was related to lower intelligence and lower cognition index. In a multivariable analysis, only age at seizure onset and cognition index were related. Conclusions: Our systematic analysis confirms proposed relationships between tuber load, epilepsy and cognitive function in tuberous sclerosis complex (TSC), but also indicates that tuber/brain proportion is a better predictor of cognitive function than tuber number and that age at seizure onset is the only independent determinant of cognitive function. Seizure control should be the principal neurointervention in patients with TSC.

Rapid antibody test for diagnosing fragile X syndrome : a validation of the technique

Abstract To date, the identification of patients and carriers of the fragile X syndrome has been carried out by DNA analysis by means of the polymerase chain reaction and Southern blot analysis. This direct DNA analysis allows both the size of the CGG repeat and methylation status of the FMR1 gene to be determined. We have recently presented a rapid antibody test on blood smears based on the presence of FMRP, the protein product of the FMR1 gene, in lymphocytes from normal individuals and the absence of FMRP in lymphocytes from patients. Here, we have tested the diagnostic value of this new technique by studying FMRP expression in 173 blood smears from normal individuals and fragile X patients. The diagnostic power of the antibody test is “perfect” for males, whereas the results are less specific for females.

Malignant pancreatic tumour within the spectrum of tuberous sclerosis complex in childhood

Abstract A 12-year-old boy with tuberous sclerosis complex (TSC) presented with a large retroperitoneal tumour. Exploratory surgery revealed an infiltrative tumour originating from the pancreas, with local metastases to the lymph nodes. The histologal diagnosis was a malignant islet cell tumour. Retrospectively measured pancreatic hormone levels, however, were normal. A connection between the malignancy and TSC was demonstrated by loss of heterozygosity of the TSC2 gene in the tumour. The primary mutation Q478X in this patient was identified in exon 13 of the TSC2 gene on chromosome 16. Conclusion Pancreatic islet cell tumours have been mainly associated with multiple endocrine neoplasia syndrome type 1. In our case we demonstrate a direct relationship of this tumour to tuberous sclerosis complex, in the absence of further signs of multiple endocrine neoplasia syndrome type 1.

Overlapping neurologic and cognitive phenotypes in patients with TSC1 or TSC2 mutations

Objective: The purpose of this study was to systematically analyze the associations between different TSC1 and TSC2 mutations and the neurologic and cognitive phenotype in patients with tuberous sclerosis complex (TSC). Methods: Mutation analysis was performed in 58 patients with TSC. Epilepsy variables, including EEG, were classified. A cognition index was determined based on a comprehensive neuropsychological assessment. On three-dimensional fluid-attenuated inversion recovery MR images, an automated tuber segmentation program detected and calculated the number of tubers and the proportion of total brain volume occupied by tubers (tuber/brain proportion [TBP]). Results: As a group, patients with a TSC2 mutation had earlier age at seizure onset, lower cognition index, more tubers, and a greater TBP than those with a TSC1 mutation, but the ranges overlapped considerably. Familial cases were older at seizure onset and had a higher cognition index than nonfamilial cases. Patients with a mutation deleting or directly inactivating the tuberin GTPase activating protein (GAP) domain had more tubers and a greater TBP than those with an intact GAP domain. Patients with a truncating TSC1 or TSC2 mutation differed from those with nontruncating mutations in seizure types only. Conclusions: Although patients with a TSC1 mutation are more likely to have a less severe neurologic and cognitive phenotype than those with a TSC2 mutation, the considerable overlap between both aspects of the phenotype implies that prediction of the neurologic and cognitive phenotypes in individuals with tuberous sclerosis complex should not be based on their particular TSC1 or TSC2 mutation.

Large regional differences in the frequency of distinct BRCA1/BRCA2 mutations in 517 Dutch breast and/or ovarian cancer families

In 517 Dutch families at a family cancer clinic, we screened for BRCA1/2 alterations using the Protein Truncation Test (PTT) covering approximately 60% of the coding sequences of both genes and direct testing for a number of previously identified Dutch recurrent mutations. In 119 (23%) of the 517 families, we detected a mutation in BRCA1 (n=98; 19%) or BRCA2 (n=21; 4%). BRCA1/2 mutations were found in 72 (52%) of 138 families with breast and ovarian cancer (HBOC), in 43 (13%) of the 339 families with breast cancer only (HBC), in 4 (36%) of 11 families with ovarian cancer only (HOC), and in nine of 29 families with one single young case (<40 years) of breast cancer. Between the different subgroups of families (subdivided by the number of patients, cancer phenotype and age of onset) the proportion of BRCA1/2 mutations detected, varied between 6 and 82%. Eight different mutations, each encountered in at least six distinct families, represented as much as 61% (73/119 families) of all mutations found. The original birthplaces of the ancestors of carriers of these eight recurrent mutations were traced. To estimate the relative contribution of two important regional recurrent mutations (BRCA1 founder mutation IVS12-1643del3835 and BRCA2 founder mutation 5579insA) to the overall occurrence of breast cancer, we performed a population-based study in two specific small regions. The two region-specific BRCA1 and BRCA2 founder mutations were detected in 2.8% (3/106) and 3.2% (3/93) of the unselected breast tumours, respectively. Of tumours diagnosed before the age of 50 years, 6.9% (3/43) and 6.6% (2/30) carried the region-specific founder mutation. Thus, large regional differences exist in the prevalence of certain specific BRCA1/BRCA2 founder mutations, even in very small areas concerning populations of approximately 200000 inhabitants.