Analysis of rare disruptive germline mutations in 2135 enriched BRCA-negative breast cancers excludes additional high-impact susceptibility genes.

BACKGROUND: Breast cancer has a significant heritable basis, of which ∼60% remains unexplained. Testing for BRCA1/BRCA2 offers useful discrimination of breast cancer risk within families, and identification of additional breast cancer susceptibility genes could offer clinical utility. PATIENTS AND METHODS: We included 2135 invasive breast cancer cases recruited via the Breast and Ovarian Cancer Susceptibility study, a retrospective UK study of familial breast cancer. ELIGIBILITY CRITERIA: female, BRCA-negative, white European ethnicity, and one of: (i) breast cancer family history, (ii) bilateral disease, (iii) young age of onset (<30 years), and (iv) concomitant ovarian cancer. We undertook exome sequencing of cases and carried out gene-level burden testing of rare damaging variants against those from 51 377 ethnicity-matched population controls from gnomAD. RESULTS: 159/2135 (7.4%) cases had a qualifying variant in an established breast cancer susceptibility gene, with minimal evidence of signal in other cancer susceptibility genes. Known breast cancer susceptibility genes PALB2, CHEK2, and ATM were the only genes to retain statistical significance after correcting for multiple testing. Due to the enrichment of hereditary cases in the series, we had good power (>80%) to detect a gene of BRCA1-like risk [odds ratio (OR) = 10.6] down to a population minor allele frequency of 4.6 × 10-5 (1 in 10 799, less than one-tenth that of BRCA1)and of PALB2-like risk (OR = 5.0) down to a population minor allele frequency of 2.8 × 10-4 (1 in 1779, less than half that of PALB2). Power was lower for identification of novel moderate penetrance genes (OR = 2-3) like CHEK2 and ATM. CONCLUSIONS: This is the largest case-control whole-exome analysis of enriched breast cancer published to date. Whilst additional breast cancer susceptibility genes likely exist, those of high penetrance are likely to be of very low mutational frequency. Contention exists regarding the clinical utility of such genes.

Genetic counselling and consent for tumour testing in HNPCC.

Molecular pathological tests are performed on stored tumour material in order to identify individuals with hereditary non-polyposis colorectal cancer. We have previously identified that there is widespread use of this testing and now describe what counselling occurs prior to testing and the approaches in seeking consent. A respondent from every cancer genetic centre in UK offering microsatellite instability and/or immunohistochemistry testing (n= 20, response rate = 100%) was interviewed in order to ascertain pre-test counselling and consent protocols. Individuals providing consent are not always seen in person prior to providing consent but few services had supporting written information. Nine (of 19) consent forms documented consent to perform genetic testing, while the majority (14/19) sought consent to release pathology samples to the genetic service. Less than half of the services routinely seek consent to test samples from a deceased individual. Concerns were raised about spousal consent when the implications of results are for blood relatives. The differences identified between genetic counselling for testing of tumour tissue and for germ-line genetic testing suggest that counselling protocols specific for somatic testing should be developed. The results are discussed in the context of a changing legal environment and anticipated growing demand for testing.

Variability and inequity in testing of somatic tissue for hereditary cancer: a survey of UK clinical practice.

A growing body of literature demonstrates the benefits of molecular pathological investigations of tumour material in the identification of individuals with hereditary non-polyposis colorectal cancer and debates the best detection strategies. This testing is novel as it is the first widespread use of somatic tissue testing to inform genetic analysis and requires the co-ordination of both histopathology and molecular genetics laboratories. However, the clinical use and experience of microsatellite instability (MSI) testing and immunohistochemical analysis have not been reported. A respondent from every cancer genetics centre in the UK (n= 24, response rate 100%) and laboratory performing MSI testing (n= 5, response rate 100%) was interviewed by telephone to ascertain test availability, testing methods, eligibility criteria and post-test management. Twenty centres (83%) offer eligible clients at least one form of tumour testing, and all use tumour testing to determine who should have access to germ line genetic testing. However, no two laboratories used the same testing methods, seven different testing strategies were applied and there was considerable variation in eligibility criteria. The implications of these variations are considered, and recommendations for the development of a consistent service for testing of somatic tissue offered.

Screening for familial ovarian cancer--management and outcome of women with moderate to high risk of developing ovarian cancer.

Five percent to ten percent of ovarian cancers are hereditary. Individual genetic risk of developing ovarian malignancy is discussed in women. Currently, prophylactic surgery is advised to women with a moderate to high risk of developing ovarian cancer. Workload and outcome of the multidisciplinary familial ovarian screening clinic in South Wales were assessed. This was an observational study of 145 women registered with the Familial Ovarian Screening Clinic between January 1998 and December 2003. The data were retrieved from the medical notes. Yearly follow-ups were investigated with a transvaginal scan and CA125 level. Post-surgery women were followed up with yearly CA125 estimations: 46.9% fell into moderate-risk and 50.3% into high-risk category. The median age was 42 (SD 10.4), 71.7% were pre menopausal, and 10.3% had a personal history of breast cancer and 1.4% colon cancer. Whereas 36.5% opted for surgery, the remaining women (but two) opted for annual follow-up. Histology of the women who had surgery showed three cases of malignancies (fallopian tube carcinoma, atypical ovarian epithelial cells, and metastatic breast cancer). Seven women developed breast cancer during the observation period. The follow-up period is too short to come to a final conclusion as to the benefits of yearly screening in this group of women. In our series, a significant number of patients developed malignancies, despite prophylactic surgery.

Falls and stumbles in myotonic dystrophy.

OBJECTIVE: To investigate falls and risk factors in patients with myotonic dystrophy type 1 (DM1) compared with healthy volunteers. METHODS: 13 sequential patients with DM1 from different kindreds were compared with 12 healthy volunteers. All subjects were evaluated using the Rivermead Mobility Index, Performance Oriented Mobility Assessment, and modified Activities Specific Balance Confidence scale. Measures of lower limb muscle strength, gait speed, and 7-day ambulatory activity monitoring were recorded. Subjects returned a weekly card detailing stumbles and falls. RESULTS: 11 of 13 patients (mean age 46.5 years, seven female) had 127 stumbles and 34 falls over the 13 weeks, compared with 10 of 12 healthy subjects (34.4 years, seven female) who had 26 stumbles and three falls. Patients were less active than healthy subjects but had more falls and stumbles per 5000 right steps taken (mean (SD) events, 0.21 (0.29) v 0.02 (0.02), p = 0.007). Patients who fell (n = 6) had on average a lower Rivermead Mobility score, slower self selected gait speed, and higher depression scores than those who did not. CONCLUSIONS: DM1 patients stumble or fall about 10 times more often than healthy volunteers. Routine inquiry about falls and stumbles is justified. A study of multidisciplinary intervention to reduce the risk of falls seems warranted.

An exploratory comparison of genetic counselling protocols for HNPCC predictive testing.

Most UK genetics centres offering predictive testing for hereditary non-polyposis colorectal cancer (HNPCC) use an extended counselling protocol originally developed for Huntington's disease. Shortened counselling may be more appropriate in the context of treatable genetic conditions such as HNPCC. Twenty-six high-risk individuals were randomized to extended genetic counselling (two sessions of education and reflection held 1 month apart) or shortened genetic counselling (a single educational session) prior to HNPCC testing. Prospective questionnaires, interviews and transcripts of counselling sessions were analysed. Participants were unsure what to expect prior to genetic counselling and had already decided to undergo genetic testing. There was no evidence of psychological harm caused by shortened genetic counselling, with a high level of satisfaction with the counselling received in both groups. Reflective counselling occurred in both groups but was framed in terms of practical action and information. Participants expressed differing preferences for the level of information received. This exploratory study indicates that shortened genetic counselling may be an appropriate means of supporting decisions already made by individuals about HNPCC testing. However, participants would benefit from preparatory information to help them reflect on issues not previously considered, which can then be explored more fully as part of a tailored counselling approach.

A locus for autosomal dominant "pure" hereditary spastic paraplegia maps to chromosome 19q13.

Genetic loci for autosomal dominant pure hereditary spastic paraplegia (ADPHSP) have been mapped to chromosomes 2p, 8q, 12q, 14q, and 15q. We undertook a genomewide linkage screen of a large family with ADPHSP, for which linkage at all previously identified ADPHSP loci was excluded. Analysis of markers on chromosome 19q gave a peak pairwise LOD score of 3.72 at D19S420, allowing assignment of a novel ADPHSP locus (which we have termed "SPG12") to this region. Haplotype construction and analysis of recombination events narrowed the SPG12 locus to a 16.1-cM region between markers D19S868 and D19S902.

Locus-phenotype correlations in autosomal dominant pure hereditary spastic paraplegia. A clinical and molecular genetic study of 28 United Kingdom families.

This study aimed to describe the clinical phenotype of a large collection of families with autosomal dominant pure hereditary spastic paraplegia (ADPHSP), to examine the relative frequency of each of the three known ADPHSP genes within this population, to assess locus-phenotype correlation in ADPHSP and to ascertain whether there are clinical subgroups within genetically defined populations of ADPHSP families. We examined 306 family members, 144 affected, from 28 families with ADPHSP. Linkage analysis at the three known ADPHSP loci allowed us to categorize the families into three groups: (i) those families showing linkage to the chromosome 2 ADPHSP locus (seven families); (ii) those in which linkage to all known loci was excluded (five families); and (iii) those in which linkage results were inconclusive. There was a correlation between linkage group and clinical features, with chromosome 2-linked families having a later age at onset of symptoms (P = 0.001) and later age before commencing walking stick use (P = 0.007) than those families in which linkage to all known ADPHSP loci was excluded. There were no clinical differences between the families showing linkage to the chromosome 2 locus, but there were clinical differences between the families in which linkage to all of the known loci had been excluded (P < 0.0001). We conclude that the chromosome 2 ADPHSP gene is a frequent cause of ADPHSP in UK families, that the responsible gene has not yet been mapped in a significant proportion of families and that certain clinical features of ADPHSP, including age at onset, are at least in part determined by genetic locus.

PROMM: the expanding phenotype. A family with proximal myopathy, myotonia and deafness.

We describe a family with a proximal myopathy, subclinical EMG myotonia, cataracts and deafness. Transmission through two generations and down the male line confirms autosomal dominant inheritance. There was no abnormal expansion of the CTG triplet repeat in the last exon of the dystrophia myotonica protein kinase (DMPK) gene associated with myotonic dystrophy. Heteroduplex analysis of all but the promoter region of the DMPK gene has excluded point mutations in this gene as an underlying cause for this myotonic disorder. The family was not sufficiently informative to exclude linkage to the sodium channel gene SCN4A or the chloride channel gene CLC1. This family clearly fulfils the recently established diagnostic criteria for PROMM (proximal myotonic myopathy) and in addition shows consistent severe deafness as a hitherto undescribed feature of PROMM. We discuss the diagnostic criteria of PROMM in relation to this family and other recent papers, all of which would now fulfil the aforementioned diagnostic criteria for PROMM.

Muscle pain as a prominent feature of facioscapulohumeral muscular dystrophy (FSHD): four illustrative case reports.

Clinical studies of facioscapulohumeral muscular dystrophy (FSHD) rarely report muscle pain as a significant feature of the condition. We report four adult patients with FSHD in whom muscle pain was a presenting complaint and remains their most disabling symptom. These four patients were investigated using a pain questionnaire and diary. Inflammatory and metabolic causes of muscle pain were sought by muscle biopsy and a range of biochemical investigations. All patients reported between three and seven different pains of varying site and nature. None of the group had more than one painfree day per month and all complained of disturbed sleep. While some pains could potentially be attributed to postural problems, others were clearly myalgic in nature, though most often not specifically exercise-related. These myalgic pains could be particularly difficult to control. Results of metabolic investigations and muscle biopsy revealed no clue to the pathogenesis of these pains and there was no evidence for any exceptional inflammatory response. We believe that pain in FSHD is an under-reported but significant symptom and that further work is necessary to determine its prevalence, understand its cause and provide effective treatment.

Improved molecular diagnosis of facioscapulohumeral muscular dystrophy (FSHD): validation of the differential double digestion for FSHD.

A major advance in the molecular diagnosis of facioscapulohumeral muscular dystrophy is the recently reported elimination of confounding DNA fragments arising from homologous sequences located at 10q26. In order to evaluate the specificity and sensitivity of this important diagnostic test, we have compared a group of 130 patients fulfilling the diagnostic criteria for FSHD with 200 control subjects not known to have an increased risk of having an FSHD mutation. Among the FSHD cases the smallest BlnI/EcoRI fragment sizes ranged from 10 to > 48 kb with 94.6% (95% CI 89.2-97.8%) of cases having fragment sizes of 34 kb or less. Among the 400 chromosomes from controls the smallest BlnI/EcoRI fragment observed with the EcoRI/BlnI double restriction enzyme digest was 38 kb +/- 2 kb, suggesting a test specificity at a fragment size < 34 kb of or very near to 100% (lower 95% CI 98.2%). Test sensitivity at < 34 kb is estimated at 94.6% (95% CI 89.2-97.8%), all outliers having fragments > 38 kb. The Southern blot analysis with DNA probe p13E-11 has created a valuable molecular diagnostic test for FSHD.