Chaotic saddles and interior crises in a dissipative nontwist system

We consider a dissipative version of the standard nontwist map. Nontwist systems present a robust transport barrier, called the shearless curve, that becomes the shearless attractor when dissipation is introduced. This attractor can be regular or chaotic depending on the control parameters. Chaotic attractors can undergo sudden and qualitative changes as a parameter is varied. These changes are called crises, and at an interior crisis the attractor suddenly expands. Chaotic saddles are nonattracting chaotic sets that play a fundamental role in the dynamics of nonlinear systems; they are responsible for chaotic transients, fractal basin boundaries, and chaotic scattering, and they mediate interior crises. In this work we discuss the creation of chaotic saddles in a dissipative nontwist system and the interior crises they generate. We show how the presence of two saddles increases the transient times and we analyze the phenomenon of crisis induced intermittency.

Analysis of rare disruptive germline mutations in 2,135 enriched BRCA-negative breast cancers excludes additional high-impact susceptibility genes

BACKGROUND

Breast cancer has a significant heritable basis, of which approximately 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 2,135 invasive breast cancer cases recruited via the BOCS 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), iv) concomitant ovarian cancer. We undertook exome sequencing of cases and performed 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 = 10.6) down to a population minor allele frequency of 4.6 x 10^-5 (1 in 10,799, less than one tenth that of BRCA1)and of PALB2-like risk (odds ratio = 5.0) down to a population minor allele frequency of 2.8 x 10^-4 (1 in 1,779, less than half that of PALB2). Power was lower for identification of novel moderate penetrance genes (odds ratio = 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.

Development and Preliminary Evaluation of a Quality-of-Life Questionnaire for Adults with Neurofibromatosis Type 1 (NF1-AdQOL)

BACKGROUND

Neurofibromatosis type 1 (NF1) is a variable and unpredictable multisystem genetic disorder which predisposes to medical complications, cognitive impairment and disfigurement, of all which can impact negatively upon the health related quality of life (HRQOL) of affected adults.

OBJECTIVES

To develop and validate a disease specific HRQOL adult questionnaire to evaluate effects of NF1 from the patient's viewpoint.

METHODS

The NF1 adult HRQOL questionnaire (NF1-AdQOL) was developed based on patient interviews (n=8), survey of clinicians and piloting of the questionnaire. Adults with NF1 (n=114, 18-40 years) were recruited from three Australian genetics clinics and completed the NF1-AdQOL, Skindex-29 and Short Form-36v2 (SF-36v2) questionnaires. An exploratory factor analysis of the NF1-AdQOL was conducted to assess construct validity. Convergent and discriminant validity of the NF1-AdQOL was determined by using the multi-trait multi-method with Skindex-29 and SF-36v2 scores.

RESULTS

Factor analysis indicated that 62.7% of the common variance could be explained by three factors labelled as 'emotions associated with cosmetic appearance' (12 items), 'social functioning and learning' (11 items) and 'physical symptoms' (8 items). NF1-AdQOL had good internal consistency (Cronbach's α = 0.96). Convergent validity was confirmed by moderate associations with similarly named scales of the Skindex-29 and SF-36v2. Results from all HRQOL questionnaires indicated overall healthy HRQOL for young adults with NF1.

CONCLUSIONS

NF1-AdQOL is a relatively valid, feasible and fairly easy to read tool to measure QOL in adults with NF1. Further evaluation is required to determine its test-retest reliability, responsiveness and validity in larger adult NF1 cohorts.

Zonisamide safety in pregnancy: Data from the UK and Ireland epilepsy and pregnancy register

BACKGROUND

Animal data suggest teratogenic effects with zonisamide use and risk of pregnancy losses. Human data following zonisamide exposure are presently limited, but suggest low risk of malformation with elevated risk of low birth weight.

OBJECTIVE

To calculate the major congenital malformation (MCM) rate of zonisamide in human pregnancy and assess for a signal of any specific malformation pattern and associations with birth weight.

METHODS AND MATERIALS

Data were obtained from the UK and Ireland Epilepsy and Pregnancy register (UKIEPR) which is an observational, registration, and follow up study from December 1996 to July 2020. Eligibility criteria were use of zonisamide and to have been referred to the UKIEPR before the outcome of the pregnancy was known. Primary outcome was evidence of MCM.

RESULTS

From December 1996 through July 2020 there were 112 cases of first trimester exposure to zonisamide, including 26 monotherapy cases. There were 3 MCM for monotherapy cases (MCM rate 13.0% (95% confidence interval 4.5-32.1)), and 5 MCM for polytherapy cases (MCM rate 6.9% (95% confidence interval 3.0-15.2)). While the median birth weight was on 71st and 44th centile for monotherapy and polytherapy cases respectively, there was a high rate of infants born small for gestational age (21% for both).

CONCLUSION

These data raise concerns about a signal for potential teratogenicity with zonisamide in human pregnancy. Given the low numbers reported, further data will be required to adequately counsel women who use zonisamide in pregnancy.

Oral dimethyl fumarate induces changes within the peripheral neutrophil compartment of patients with psoriasis that are linked with skin improvement

BACKGROUND

Dimethyl fumarate (DMF) is a treatment for moderate-to-severe psoriasis and multiple sclerosis. DMF therapy typically improves skin inflammation within the first 3 months of treatment. DMF is a prodrug that generates the hydroxycarboxylic acid receptor 2 (HCA2) agonist, monomethyl fumarate (MMF). Despite widespread clinical use, DMF's mechanism of action is not fully understood.

OBJECTIVES

We wished to characterize the changes induced by DMF in peripheral neutrophils within the first 3 months of treatment to better understand its early antipsoriatic effects.

METHODS

Flow cytometry was used to assess T-cell and neutrophil frequencies, apoptosis and activation phenotype. In vitro culture of neutrophils with DMF and MMF was used to evaluate apoptosis and HCA2 internalization. Serum levels of neutrophil degranulation products were measured by enzyme-linked immunosorbent assay.

RESULTS

Patients with psoriasis had significantly higher leucocyte counts at baseline compared with controls, with a large population of pro-inflammatory CD62L^lo  CD11b^bright neutrophils. Analysis revealed that DMF treatment reduced the frequency of CD62L^lo  CD11b^bright neutrophils and serum levels of neutrophil activation markers. This reduction was not linked to increased apoptosis.

CONCLUSIONS

Our results reveal a novel in vivo effect of DMF therapy on pro-inflammatory neutrophils that likely contributes to this treatment's antipsoriatic efficacy.

Epi-Two-Dimensional Fluid Flow: A New Topological Paradigm for Dimensionality

While a variety of fundamental differences are known to separate two-dimensional (2D) and three-dimensional (3D) fluid flows, it is not well understood how they are related. Conventionally, dimensional reduction is justified by an a priori geometrical framework; i.e., 2D flows occur under some geometrical constraint such as shallowness. However, deeper inquiry into 3D flow often finds the presence of local 2D-like structures without such a constraint, where 2D-like behavior may be identified by the integrability of vortex lines or vanishing local helicity. Here we propose a new paradigm of flow structure by introducing an intermediate class, termed epi-two-dimensional flow, and thereby build a topological bridge between 2D and 3D flows. The epi-2D property is local and is preserved in fluid elements obeying ideal (inviscid and barotropic) mechanics; a local epi-2D flow may be regarded as a "particle" carrying a generalized enstrophy as its charge. A finite viscosity may cause "fusion" of two epi-2D particles, generating helicity from their charges giving rise to 3D flow.

Uptake of health monitoring and disease self-management in Australian adults with neurofibromatosis type 1: strategies to improve care

Lifelong health monitoring is recommended in neurofibromatosis type 1 (NF1) because of the progressive and unpredictable range of disabling and potentially life-threatening symptoms that arise. In Australia, strategies for NF1 health surveillance are less well developed for adults than they are for children, resulting in inequalities between pediatric and adult care. The aims of this study were to determine the uptake of health monitoring and capacity of adults with NF1 to self-manage their health. Australian adults with NF1 (n = 94, 18-40 years) participated in a semi-structured interview. Almost half reported no regular health monitoring. Thematic analysis of interviews identified four main themes as to why: (i) did not know where to seek care, (ii) unaware of the need for regular monitoring, (iii) futility of health monitoring as nothing can be done for NF1, and (iv) feeling healthy, therefore monitoring unnecessary. Overall, there were low levels of patient activation, indicating that adults with NF1 lacked knowledge and confidence to manage their health and health care. Findings are discussed in the context of service provision for adults with NF1 in New South Wales, Australia.

Variational necessary and sufficient stability conditions for inviscid shear flow

A necessary and sufficient condition for linear stability of inviscid parallel shear flow is formulated by developing a novel variational principle, where the velocity profile is assumed to be monotonic and analytic. It is shown that unstable eigenvalues of Rayleigh's equation (which is a non-self-adjoint eigenvalue problem) can be associated with positive eigenvalues of a certain self-adjoint operator. The stability is therefore determined by maximizing a quadratic form, which is theoretically and numerically more tractable than directly solving Rayleigh's equation. This variational stability criterion is based on the understanding of Kreĭn signature for continuous spectra and is applicable to other stability problems of infinite-dimensional Hamiltonian systems.

Malformation risks of antiepileptic drug monotherapies in pregnancy: updated results from the UK and Ireland Epilepsy and Pregnancy Registers

OBJECTIVES

Antiepileptic drug (AED) exposure during pregnancy increases the risk of major congenital malformations (MCMs). The magnitude of this risk varies by AED exposure. Here we provide updated results from the UK Epilepsy and Pregnancy Register of the risk of MCMs after monotherapy exposure to valproate, carbamazepine and lamotrigine.

METHODS

Fifteen-year prospective observational study from 1996 until 2012. The main outcome measure is the MCM rate.

RESULTS

Informative outcomes were available for 5206 cases. 1290 women were exposed to valproate monotherapy, 1718 to carbamazepine monotherapy and 2198 to lamotrigine monotherapy. The MCM risk with valproate monotherapy exposure in utero was 6.7% (95% CI 5.5% to 8.3%) compared with 2.6% with carbamazepine (95% CI 1.9% to 3.5%) and 2.3% with lamotrigine (95% CI 1.8% to 3.1%). A significant dose effect was seen with valproate (p=0.0006) and carbamazepine (p=0.03) exposed pregnancies. A non-significant trend towards higher MCM rate with increasing dose was found with lamotrigine. MCM rate for high-dose lamotrigine (>400 mg daily) was lower than the MCM rate for pregnancies exposed to <600 mg daily of valproate, but this was not significant (3.4% vs 5.0%, p=0.31).

CONCLUSIONS

In utero exposure to valproate carries a significantly higher MCM risk than lamotrigine (p=0.0001) and carbamazepine (p=0.0001) monotherapy. In contrast to prior findings, high-dose lamotrigine was associated with fewer MCMs than all doses of valproate. While lamotrigine has a favourable profile compared with valproate for adverse pregnancy outcomes, the requirements for seizure control should not be overlooked.

The effect of socioeconomic status on treatment and pregnancy outcomes in women with epilepsy in Scotland

Compared to the background population, people with epilepsy tend to have lower rates of education and employment, lower rates of marriage and childbearing, and lower overall socioeconomic status (SES). Disparities in epilepsy care based on sociodemographic factors have been observed in the literature, but it is not known whether any such disparities exist in the UK. The UK Epilepsy and Pregnancy Register is a prospective, observational, registration and follow-up study that was set up to determine the relative safety of all AEDs taken in pregnancy. Here, we report outcomes of registered pregnancies to women with epilepsy living in Scotland from December 1996 to June 2012, based on the degree of socioeconomic deprivation of their postcode area. The Scottish Index of Multiple Deprivation (SIMD) quintile scores from 2006 were used to determine degree of socioeconomic deprivation, and group 1 (most deprived) and group 5 (least deprived) were compared. There were 1526 pregnancies with complete outcome data to women living in Scotland. Of these, 1453 (95.1%) resulted in a live birth and 68 (4.7%) had a major congenital malformation (MCM). Postcodes could not be reliably identified or verified for an additional three women, who have been excluded from SIMD group analysis. Of all women included in this study, 32.4% were in group 1 and 13.2% in group 5. No difference in MCM rate was observed between the two groups (4.4% in group 1 compared to 4.7% in group 5, p=0.84). Women in group 5 were more likely to take preconceptual folic acid (56.8% compared to 14.0%, relative risk: 4.1; 95% CI: 3.1-5.2) and less likely to have generalized tonic-clonic seizures in pregnancy (13.0% compared to 29.2%, relative risk: 0.4; 95% CI: 0.3-0.7) than those in group 1. Women in group 5 were more likely to be on monotherapy regimens (80.2% compared to 65.9%, relative risk: 1.2; 95% CI: 1.1-1.3), less likely to be on valproate (19.5% compared to 28.0%, p=0.05), and more likely to be on lower doses of the drug (825.9mg/day compared to 1012.0mg/day, p=0.05) compared to those in group 1. Although no change in MCM rate was seen based on SES, differences in treatment between socioeconomic groups do exist, particularly for preconceptual folic acid consumption, AED regimen, and seizure frequency. Greater emphasis on the importance of preconceptual counseling, both to discuss AED choice and folic acid intake, would be of benefit, particularly to those living in areas of high socioeconomic deprivation, to improve equity of healthcare delivery for women with epilepsy in Scotland.

Effective transport barriers in nontwist systems

In fluids and plasmas with zonal flow reversed shear, a peculiar kind of transport barrier appears in the shearless region, one that is associated with a proper route of transition to chaos. These barriers have been identified in symplectic nontwist maps that model such zonal flows. We use the so-called standard nontwist map, a paradigmatic example of nontwist systems, to analyze the parameter dependence of the transport through a broken shearless barrier. On varying a proper control parameter, we identify the onset of structures with high stickiness that give rise to an effective barrier near the broken shearless curve. Moreover, we show how these stickiness structures, and the concomitant transport reduction in the shearless region, are determined by a homoclinic tangle of the remaining dominant twin island chains. We use the finite-time rotation number, a recently proposed diagnostic, to identify transport barriers that separate different regions of stickiness. The identified barriers are comparable to those obtained by using finite-time Lyapunov exponents.

Breast cancer in Irish families with Lynch syndrome

1543

Background: Breast cancer is not among the recognised malignant manifestations of Lynch Syndrome which include colorectal, endometrial, gastric, ovarian and upper urinary tract tumours. In this study we report the prevalence of breast cancer in Irish Lynch Syndrome families and determine immunohistochemical (IHC) expression of mismatch repair proteins (MMR) in available breast cancer tissue. Methods: Breast cancer prevalence was determined among Lynch Syndrome kindreds from two institutions in Ireland. One kindred was omitted due to a biallelic MMR and BRCA1 mutation.The clinicopathological data that was collected on breast cancer cases included age of onset, morphology, and hormone receptor status, and a genotype phenotype correlation was investigated. Immunohistochemical staining was performed for MLH1, MSH2, MSH6, and PMS2 on all available breast cancer tissue from affected individuals. Results: The distribution of MMR mutations seen in sixteen pedigrees were as follows; MLH1 (n=5), MSH2 (7), MSH6 (3), PMS2 (1). Sixty cases of colorectal cancer and 14 cases of endometrial cancer were seen. Seven breast cancers (5 invasive ductal and 2 invasive lobular cancers) and 1 case of ductal carcinoma in situ were reported in 7 pedigrees. This compared with 4 cases of prostate cancer. Of the 7 LS kindreds containing breast cancer, 6 MSH2 mutations and 1 MSH6 mutations were identified. Median age of breast cancer diagnosis was 49 years (range 38-57). Hormone receptor status is available on 3 breast cancer cases at time of abstract submission; all were ER positive and HER 2 negative. All cases had grade 2 or 3 tumours. 5 samples were available for IHC evaluation. 3 out of 5 cases showed loss of MMR expression, all showed loss of MSH2 and MSH6 expression. One of the two cases with normal IHC expression in breast tissue belonged to a kindred where 3 siblings with colorectal cancer and documented deleterious mutations demonstrated no IHC loss. Conclusions: Breast cancer occurred at an early age and was more common than prostate cancer in Irish Lynch Syndrome pedigrees. All identified breast cancer were in kindreds with MSH2 or MSH6 mutations. Enhanced breast cancer screening may be warranted in certain Lynch Syndrome kindreds.

Familial ossification of the stylohyoid ligament in a three generation family--a new clinical entity displaying autosomal dominant inheritance

Ossification of the stylohyoid ligament is very common in the Caucasian population. More than 9000 descriptions of apparently isolated case reports on PubMed have been cited over the last 20 years, often associated with an incidental finding on imaging after neck trauma. No cases of familial ossification have been described. We document a family with several affected members, each with an ossified stylohyoid ligament, confirming that ossification may be hereditary in some families and is most likely due to an autosomal dominant gene.

Breast cancer in Irish families with Lynch syndrome

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Background: Breast cancer is not a recognised malignant manifestation of Lynch Syndrome which includes colorectal, endometrial, gastric, ovarian and upper urinary tract tumours. In this study we report the prevalence of breast cancer in Irish Lynch Syndrome families and determine immunohistochemical expression of mismatch repair proteins (MMR) in available breast cancer tissue.

Methods: Breast cancer prevalence was determined among Lynch Syndrome kindreds from two institutions in Ireland, and a genotype phenotype correlation was investigated. One kindred was omitted due to the presence of a biallelic MMR and BRCA1 mutation. The clinicopathological data that was collected on breast cancer cases included age of onset, morphology, and hormone receptor status. Immunohistochemical staining was performed for MLH1, MSH2, MSH6, and PMS2 on all available breast cancer tissue from affected individuals.

Results: The distribution of MMR mutations seen in 16 pedigrees was as follows; MLH1 (n=5), MSH2 (7), MSH6 (3), PMS2 (1). Sixty cases of colorectal cancer and 14 cases of endometrial cancer were seen. Seven breast cancers (5 invasive ductal and 2 invasive lobular cancers) and 1 case of ductal carcinoma in situ were reported in 7 pedigrees. This compared with 4 cases of prostate cancer. Six MSH2 mutations and 1 MSH6 mutation were identified in the 7 Lynch syndrome kindreds. Median age of breast cancer diagnosis was 49 years (range 38-57). Hormone receptor status is available on 3 breast cancer cases at time of abstract submission; all were ER positive and HER 2 negative. All cases had grade 2 or 3 tumours. Final results of immunohistochemistry for mismatch repair protein expression on breast cancer samples are pending and will be reported at the meeting. One breast cancer has been tested to date and demonstrated loss of MSH2 protein expression in an individual carrying an MSH2 mutation.

Conclusions: Breast cancer occurred at an early age and was more common than prostate cancer in Irish Lynch Syndrome pedigrees. All reported breast cancer cases were in kindreds with MSH2 or MSH6 mutations. Enhanced breast cancer screening may be warranted in certain Lynch Syndrome kindreds.

Enhanced lymphocyte interferon (IFN)-γ responses in a PTEN mutation-negative Cowden disease kindred

Identification of immune modifiers of inherited cancer syndromes may provide a rationale for preventive therapy. Cowden disease (CD) is a genetically heterogeneous inherited cancer syndrome that arises predominantly from germline phosphatase and tensin homologue deleted on chromosome 10 (PTEN) mutation and increased phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) signalling. However, many patients with classic CD diagnostic features are mutation-negative for PTEN (PTEN M-Neg). Interferon (IFN)-γ can modulate the PI3K/mTOR pathway, but its association with PTEN M-Neg CD remains unclear. This study assessed IFN-γ secretion by multi-colour flow cytometry in a CD kindred that was mutation-negative for PTEN and other known susceptibility genes. Because IFN-γ responses may be regulated by killer cell immunoglobulin-like receptors (KIR) and respective human leucocyte antigen (HLA) ligands, KIR/HLA genotypes were also assessed. Activating treatments induced greater IFN-γ secretion in PTEN M-Neg CD peripheral blood lymphocytes versus healthy controls. Increased frequency of activating KIR genes, potentially activating KIR/HLA compound genotypes and reduced frequency of inhibitory genotypes, were found in the PTEN M-Neg CD kindred. Differences of IFN-γ secretion were observed among PTEN M-Neg CD patients with distinct KIR/HLA compound genotypes. Taken together, these findings show enhanced lymphocyte secretion of IFN-γ that may influence the PI3K/mTOR CD causal molecular pathway in a PTEN mutation-negative CD kindred.

Uptake of Huntington disease predictive testing in a complete population

Using the Northern Ireland Huntington disease (HD) register, the number of prospectively recorded predictive tests was analysed over a 20-year period. Two hundred and twelve patients completed predictive testing. Ninety-two (43%) received mutation-positive results and 119 (56%) mutation negative. There was one intermediate allele result. There was no significant gender difference. One hundred and eighty affected cases confirmed by molecular genetic testing were alive on 1 January 2001. The uptake of predictive testing in the entire HD 50% at-risk population in 2001 was calculated by three methods giving a range of 12.3-14.6%. Uptake after 20 years was estimated to be 14.7%. The minimum prevalence of affected HD cases was calculated as 10.6/100,000 in 2001. The total uptake of predictive testing was calculated and it suggests that a substantial number of at-risk patients do not come forward for testing until symptomatic. Pre-symptomatic testing for this late-onset condition with no present treatment, and limited management options, still presents challenges for families.

Transport properties in nontwist area-preserving maps

Nontwist systems, common in the dynamical descriptions of fluids and plasmas, possess a shearless curve with a concomitant transport barrier that eliminates or reduces chaotic transport, even after its breakdown. In order to investigate the transport properties of nontwist systems, we analyze the barrier escape time and barrier transmissivity for the standard nontwist map, a paradigm of such systems. We interpret the sensitive dependence of these quantities upon map parameters by investigating chaotic orbit stickiness and the associated role played by the dominant crossing of stable and unstable manifolds.

Evaluation of a candidate breast cancer associated SNP in ERCC4 as a risk modifier in BRCA1 and BRCA2 mutation carriers. Results from the Consortium of Investigators of Modifiers of BRCA1/BRCA2 (CIMBA)

Background:

In this study we aimed to evaluate the role of a SNP in intron 1 of the ERCC4 gene (rs744154), previously reported to be associated with a reduced risk of breast cancer in the general population, as a breast cancer risk modifier in BRCA1 and BRCA2 mutation carriers.

Methods:

We have genotyped rs744154 in 9408 BRCA1 and 5632 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and assessed its association with breast cancer risk using a retrospective weighted cohort approach.

Results:

We found no evidence of association with breast cancer risk for BRCA1 (per-allele HR: 0.98, 95% CI: 0.93–1.04, P=0.5) or BRCA2 (per-allele HR: 0.97, 95% CI: 0.89–1.06, P=0.5) mutation carriers.

Conclusion:

This SNP is not a significant modifier of breast cancer risk for mutation carriers, though weak associations cannot be ruled out.

Folic acid use and major congenital malformations in offspring of women with epilepsy: a prospective study from the UK Epilepsy and Pregnancy Register

OBJECTIVE

In the general population, folic acid supplementation during pregnancy has been demonstrated to reduce the frequency of neural tube defects (NTDs) and other major congenital malformations (MCMs). It is recommended that women with epilepsy contemplating pregnancy take supplemental folic acid because of the known antifolate effect of some antiepileptic drugs (AEDs). Here the aim was to determine the effectiveness of this practice.

METHODS

This study is part of a prospective, observational, registration and follow-up study. Suitable cases are women with epilepsy who become pregnant and who are referred before outcome of the pregnancy is known. The main outcome measure is the MCM rate. Outcomes were analysed against folic acid exposure, malformation type and drug group for the most commonly used monotherapy AEDs.

RESULTS

In 1935 cases reported to have received preconceptual folic acid, 76 MCMs (3.9%; 95% CI 3.1 to 4.9) and eight NTDs (0.4%; 95% CI 0.2 to 0.8) were identified. For 2375 women who were reported to have received folic acid but not until later in the pregnancy (n = 1825) or not at all (n = 550), there were 53 outcomes with an MCM (2.2%; 95% CI 1.7 to 2.9) and eight NTDs (0.34%; 95% CI 0.2 to 0.7).

CONCLUSIONS

The study supports the view that extrapolation from studies carried out in the general population to groups of women with epilepsy may be questionable. It may be that the increased risk of MCM recorded in this group occurs through mechanisms other than that of folic acid metabolism.

Predicting the likelihood of carrying a BRCA1 or BRCA2 mutation: validation of BOADICEA, BRCAPRO, IBIS, Myriad and the Manchester scoring system using data from UK genetics clinics

OBJECTIVES

Genetic testing for the breast and ovarian cancer susceptibility genes BRCA1 and BRCA2 has important implications for the clinical management of people found to carry a mutation. However, genetic testing is expensive and may be associated with adverse psychosocial effects. To provide a cost-efficient and clinically appropriate genetic counselling service, genetic testing should be targeted at those individuals most likely to carry pathogenic mutations. Several algorithms that predict the likelihood of carrying a BRCA1 or a BRCA2 mutation are currently used in clinical practice to identify such individuals.

DESIGN

We evaluated the performance of the carrier prediction algorithms BOADICEA, BRCAPRO, IBIS, the Manchester scoring system and Myriad tables, using 1934 families seen in cancer genetics clinics in the UK in whom an index patient had been screened for BRCA1 and/or BRCA2 mutations. The models were evaluated for calibration, discrimination and accuracy of the predictions.

RESULTS

Of the five algorithms, only BOADICEA predicted the overall observed number of mutations detected accurately (ie, was well calibrated). BOADICEA also provided the best discrimination, being significantly better (p<0.05) than all models except BRCAPRO (area under the receiver operating characteristic curve statistics: BOADICEA = 0.77, BRCAPRO = 0.76, IBIS = 0.74, Manchester = 0.75, Myriad = 0.72). All models underpredicted the number of BRCA1 and BRCA2 mutations in the low estimated risk category.

CONCLUSIONS

Carrier prediction algorithms provide a rational basis for counselling individuals likely to carry BRCA1 or BRCA2 mutations. Their widespread use would improve equity of access and the cost-effectiveness of genetic testing.

Reduced penetrance alleles for Huntington's disease: a multi-centre direct observational study

OBJECTIVE

To obtain penetrance data for Huntington's disease when DNA results are in the range of 36-39 CAG repeats and assess the consistency of reporting the upper allele from two reference centres.

METHOD

Data were collected anonymously on age of onset or age last known to be unaffected from a cohort of individuals with results in this range. DNA samples were re-analysed in two reference centres. Kaplan-Meier analysis was used to construct an age of onset curve and penetrance figures.

RESULTS

Clinical data and concordant DNA results from both reference centres were available for 176 samples; penetrance figures (and 95% confidence intervals) for this cohort, at age 65 and 75 years, were 63.9% (55.5% to 73.2%) and 74.2% (64.2% to 84.2%), respectively. Inclusion of 28 additional subjects for whom repeat DNA results were unavailable, obtained from only one reference centre, or discrepant by one repeat within this range, gave penetrance data (including 95% confidence intervals) at ages 65 and 75 years of 62.4% (54.4% to 70.4%) and 72.7.% (63.3% to 82.1%), respectively. 238 duplicate results were available from the reference centres; 10 (4.2%) differed by one CAG repeat in the reporting of the upper allele and in two (0.84%) of these cases the discrepancy was between 39 and 40 repeats.

CONCLUSION

When DNA results are in this range, a conservative approach is to say that there is at least a 40% chance the person will be asymptomatic at age 65 years and at least a 30% chance the person will be asymptomatic at age 75 years.

Predictive genetic testing for BRCA1/2 in a UK clinical cohort: three-year follow-up

This prospective multicentre study assesses long-term impact of genetic testing for breast/ovarian cancer predisposition in a clinical cohort. Areas evaluated include risk management, distress and insurance problems 3 years post-testing. Participants are adults unaffected with cancer from families with a known BRCA1/2 mutation. One hundred and ninety-three out of 285 (70% response) participants at nine UK clinical genetics centres completed assessments at 3 years: 80% female; 37% carriers of a BRCA1/2 mutation. In the 3 years, post-genetic testing carriers reported more risk management activities than non-carriers. Fifty-five per cent of female carriers opted for risk reducing surgery; 43% oophorectomy; and 34% mastectomy. Eighty-nine per cent had mammograms compared with 47% non-carriers. Thirty-six per cent non-carriers > or =50 years did not have a mammogram post-test. Twenty-two per cent male carriers had colorectal and 44% prostate screening compared with 5 and 19% non-carriers respectively. Seven per cent carriers and 1% non-carriers developed cancer. Distress levels did not differ in carriers and non-carriers at 3-year follow-up. Forty per cent of female carriers reported difficulties with life and/or health insurance. Given the return to pre-test levels of concern among female non-carriers at 3 years and a substantial minority not engaging in recommended screening, there appears to be a need to help some women understand the meaning of their genetic status.

Levetiracetam in pregnancy: Preliminary experience from the UK Epilepsy and Pregnancy Register

It is not known whether the antiepileptic drug (AED) levetiracetam can be used safely in human pregnancy. As part of a study to determine the risks of major congenital malformations (MCMs) for infants exposed to AEDs in utero, we identified all cases exposed to levetiracetam. Three of 117 exposed pregnancies had an MCM (2.7%; 95% CI 0.9% to 7.7%); all 3 were exposed to other AEDs.

Breakup of shearless meanders and "outer" tori in the standard nontwist map

The breakup of shearless invariant tori with winding number omega=(11+gamma)(12+gamma) (in continued fraction representation) of the standard nontwist map is studied numerically using Greene's residue criterion. Tori of this winding number can assume the shape of meanders [folded-over invariant tori which are not graphs over the x axis in (x,y) phase space], whose breakup is the first point of focus here. Secondly, multiple shearless orbits of this winding number can exist, leading to a new type of breakup scenario. Results are discussed within the framework of the renormalization group for area-preserving maps. Regularity of the critical tori is also investigated.

Exonic STK11 deletions are not a rare cause of Peutz-Jeghers syndrome

BACKGROUND

Peutz-Jeghers syndrome (PJS) is a rare, autosomal dominant cancer predisposition syndrome characterised by oro-facial pigmentation and hamartomatous polyposis of the gastrointestinal tract. A causal germline mutation in STK11 can be identified in 30% to 80% of PJS patients.

METHODS

Here we report the comprehensive mutational analysis of STK11 in 38 PJS probands applying conventional PCR based mutation detection methods and the recently introduced MLPA (multiplex ligation dependent probe amplification) technique developed for the identification of exonic deletions/duplications.

RESULTS

Nineteen of 38 probands (50%) had detectable point mutations or small scale deletions/insertions and six probands (16%) had genomic deletions encompassing one or more STK11 exons.

CONCLUSIONS

These findings demonstrate that exonic STK11 deletions are a common cause of PJS and provide a strong rationale for conducting a primary screen for such mutations in patients.

Tuberous sclerosis complex: clinical features, diagnosis, and prevalence within Northern Ireland

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by mutations in the TSC1 and TSC2 genes on chromosomes 9 and 16 respectively. Diagnosis is based on clinical features but can be difficult as a result of variable phenotypic expression. With the advantage of mutation analysis in making a diagnosis of TSC, and improved identification of the associated clinical features, there have been few new data on its prevalence and on the proportion of cases due to new mutations. We have performed a retrospective epidemiological study on the prevalence of TSC, the clinical features attributed to it, and the availability of mutational analysis. We identified 73 known patients with TSC (5 deceased): 39 were female and 34 male. Ages ranged from 10 months to 69 years, with a mean age of 27 years 11 months (SD 16y 10mo). The point prevalence of TSC in our study was estimated at 1 out of 24 956 on the prevalence day (30 April 2004). The majority of patients (42.5%) were diagnosed at less than 15 months of age; 25% were not given a diagnosis on first developing symptoms. In all, 93.2% had epilepsy and 71.2% had a learning disability. A mutation was identified in 95.8% of those tested (26% TSC1 and 74% TSC2). TSC2 mutations were correlated with a more severe phenotype. The new mutation rate was calculated at 64%. We conclude that the prevalence of TSC is higher than previously calculated. We recommend that all children with epilepsy be assessed for features of TSC. Larger studies will be required to assess the prevalence of mutations in each gene, and genotype-phenotype correlation.

Malformation risks of antiepileptic drugs in pregnancy: a prospective study from the UK Epilepsy and Pregnancy Register

OBJECTIVE

To assess the relative risk of major congenital malformation (MCM) from in utero exposure to antiepileptic drug (AEDs).

METHODS

Prospective data collected by the UK Epilepsy and Pregnancy Register were analysed. The presence of MCMs recorded within the first three months of life was the main outcome measure.

RESULTS

Full outcome data were collected on 3607 cases. The overall MCM rate for all AED exposed cases was 4.2% (95% confidence interval (CI), 3.6% to 5.0%). The MCM rate was higher for polytherapy (6.0%) (n = 770) than for monotherapy (3.7%) (n = 2598) (crude odds ratio (OR) = 1.63 (p = 0.010), adjusted OR = 1.83 (p = 0.002)). The MCM rate for women with epilepsy who had not taken AEDs during pregnancy (n = 239) was 3.5% (1.8% to 6.8%). The MCM rate was greater for pregnancies exposed only to valproate (6.2% (95% CI, 4.6% to 8.2%) than only to carbamazepine (2.2% (1.4% to 3.4%) (OR = 2.78 (p<0.001); adjusted OR = 2.97 (p<0.001)). There were fewer MCMs for pregnancies exposed only to lamotrigine than only to valproate. A positive dose response for MCMs was found for lamotrigine (p = 0.006). Polytherapy combinations containing valproate carried a higher risk of MCM than combinations not containing valproate (OR = 2.49 (1.31 to 4.70)).

CONCLUSIONS

Only 4.2% of live births to women with epilepsy had an MCM. The MCM rate for polytherapy exposure was greater than for monotherapy exposure. Polytherapy regimens containing valproate had significantly more MCMs than those not containing valproate. For monotherapy exposures, carbamazepine was associated with the lowest risk of MCM.

Meanders and reconnection-collision sequences in the standard nontwist map

New global periodic orbit collision and separatrix reconnection scenarios exhibited by the standard nontwist map are described in detail, including exact methods for determining reconnection thresholds, methods that are implemented numerically. Results are compared to a parameter space breakup diagram for shearless invariant curves. The existence of meanders, invariant tori that are not graphs, is demonstrated numerically for both odd and even period reconnection for certain regions in parameter space. Implications for transport are discussed.

Hereditary non-polyposis colon cancer

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Psychosocial impact of breast/ovarian (BRCA1/2) cancer-predictive genetic testing in a UK multi-centre clinical cohort

This multi-centre UK study assesses the impact of predictive testing for breast and ovarian cancer predisposition genes (BRCA1/2) in the clinical context. In the year following predictive testing, 261 adults (59 male) from nine UK genetics centres participated; 91 gene mutation carriers and 170 noncarriers. Self-report questionnaires were completed at baseline (pre-genetic testing) and 1, 4 and 12 months following the genetic test result. Men were assessed for general mental health (by general health questionnaire (GHQ)) and women for general mental health, cancer-related worry, intrusive and avoidant thoughts, perception of risk and risk management behaviour. Main comparisons were between female carriers and noncarriers on all measures and men and women for general mental health. Female noncarriers benefited psychologically, with significant reductions in cancer-related worry following testing (P<0.001). However, younger female carriers (<50 years) showed a rise in cancer-related worry 1 month post-testing (P<0.05). This returned to pre-testing baseline levels 12 months later, but worry remained significantly higher than noncarriers throughout (P<0.01). There were no significant differences in GHQ scores between males and females (both carriers and noncarriers) at any time point. Female carriers engaged in significantly more risk management strategies than noncarriers in the year following testing (e.g. mammograms; 92% carriers vs 30% noncarriers). In the 12 months post-testing, 28% carriers had bilateral risk-reducing mastectomy and 31% oophorectomy. Oophorectomy was confined to older (mean 41 yrs) women who already had children. However, worry about cancer was not assuaged by surgery following genetic testing, and this requires further investigation. In all, 20% of female carriers reported insurance problems. The data show persistent worry in younger female gene carriers and confirm changes in risk management consistent with carrier status. Men were not adversely affected by genetic testing in terms of their general mental health.

Non-uptake of predictive genetic testing for BRCA1/2 among relatives of known carriers: attributes, cancer worry, and barriers to testing in a multicenter clinical cohort

BRCA1/2 test decliners/deferrers have received almost no attention in the literature and this is the first study of this population in the United Kingdom. The aim of this multicenter study is to examine the attributes of a group of individuals offered predictive genetic testing for breast/ovarian cancer predisposition who did not wish to proceed with testing at the time of entry into this study. This forms part of a larger study involving 9 U.K. centers investigating the psychosocial impact of predictive genetic testing for BRCA1/2. Cancer worry and reasons for declining or deferring BRCA1/2 predictive genetic testing were evaluated by questionnaire following genetic counseling. A total of 34 individuals declined the offer of predictive genetic testing. Compared to the national cohort of test acceptors, test decliners are significantly younger. Female test decliners have lower levels of cancer worry than female test acceptors. Barriers to testing include apprehension about the result, traveling to the genetics clinic, and taking time away from work/family. Women are more likely than men to worry about receiving less screening if found not to be a carrier. The findings do not indicate that healthy BRCA1/2 test decliners are a more vulnerable group in terms of cancer worry. However, barriers to testing need to be discussed in genetic counseling.

Mosaic monosomy 14: clinical features and recognizable facies

A 1-year-old child with clinical features of monosomy 14 is reported. She has dysmorphic facial features including ocular colobomata, dolichocephaly and microcephaly, retinal pigmentation, severe seizures, fair curly hair and tapering fingers. There was severe mental retardation. This is the first reported case of severe mosaic monosomy 14, with up to 30% mosaicism. A recognizable facial gestalt is present in children with 14q deletions or partial monosomy 14, as well as susceptibility to infection, feeding difficulties, seizures and retinal pigmentation.

An Irish three-generation family of Cornelia de Lange syndrome displaying autosomal dominant inheritance

The existence of familial de Lange syndrome has been documented in sibs and in parent-child families, but the inheritance pattern continues to be the cause of much debate. We describe a classically affected neonate with de Lange syndrome, an affected mother and probably affected maternal grandmother. These cases show evidence for a dominantly inherited syndrome with a de Lange phenotype.

Accuracy of the clinical diagnosis of Down syndrome

OBJECTIVES

To determine the accuracy of clinical diagnosis of Down syndrome, identify problems in reaching a diagnosis, to provide recommendations for improvement and estimate a minimum prevalence for all types of Down syndrome.

DESIGN

A retrospective observational study was carried out over a five-year period. Genesis, a database located in the Department of Medical genetics, was used to identify the number of Down syndrome karyotypes including trisomy, translocation, and mosaic sample variants. Age of diagnosis was determined using date of receipt. Karyotyping requests for a clinical diagnosis of Down syndrome were also identified. Patient notes and cytogenetic laboratory reports were used to identify clinical indication for karyotyping.

SETTING

Regional Genetics Centre, covering all cytogenetic analyses for referrals within the entire Northern Ireland population.

RESULTS

208 postnatal cases of Down syndrome were identified, 197 (94.7%) trisomy, 3 (1.45%) translocation, and 8 (3.85%) mosaic variants. 112 (54.8%) were male and 96 (46.2%) female. 268 samples were taken to confirm or exclude a clinical diagnosis of Down syndrome. 185 of these had Down syndrome, 77 were normal, and 6 had another abnormality. 90% and 100% of trisomy and translocation Down syndrome respectively were diagnosed on the basis of clinical features. This fell to 37.5% of mosaic Down syndrome patients being diagnosed clinically (p < 0.001). Simian crease, sandal gap, epicanthic folds, hypotonia, upslanting palpebral fissures, and protruding tongue are the most frequent characteristic features seen. Similarly epicanthic folds, protruding tongue, simian crease and sandal gap, hypotonia, and upslanting palpebral fissures are also described in a significant proportion of karyotypically normal individuals, thus arousing a suspicion of Down syndrome. 89.4% of patients were diagnosed between day 1 and 7 of life. Of 10.6% patients diagnosed after day 7 of life, 7.6% were adults and 3% children. The minimum prevalence was estimated at 167.9 per 100,000, or 1 in 595 births.

CONCLUSION

In a defined population, with a prevalence of around 1 in 600 births, accurate clinical diagnosis occurred in 90%, 100%, and 37.5% of trisomy, translocation, and mosaic patients. 49.5% of patients had one or more of the following phenotypic findings: Simian crease, sandal gap, epicanthic folds, hypotonia, upslanting palpebral fissures, and protruding tongue. However, the same six features aroused a suspicion of Down syndrome in individuals with normal karyotyping, thus causing undue stress and worry to parents. Mosaic cases may be more common than previously recognised, and often do not have dysmorphic features. It is therefore a diagnosis that should always be considered in those who are educationally subnormal without a definitive diagnosis.

Interaction of normal and expanded CAG repeat sizes influences age at onset of Huntington disease

Huntington disease (HD) is a neurodegenerative disorder caused by the abnormal expansion of CAG repeats in the HD gene on chromosome 4p16.3. Past studies have shown that the size of expanded CAG repeat is inversely associated with age at onset (AO) of HD. It is not known whether the normal Huntington allele size influences the relation between the expanded repeat and AO of HD. Data collected from two independent cohorts were used to test the hypothesis that the unexpanded CAG repeat interacts with the expanded CAG repeat to influence AO of HD. In the New England Huntington Disease Center Without Walls (NEHD) cohort of 221 HD affected persons and in the HD-MAPS cohort of 533 HD affected persons, we found evidence supporting an interaction between the expanded and unexpanded CAG repeat sizes which influences AO of HD (P = 0.08 and 0.07, respectively). The association was statistically significant when both cohorts were combined (P = 0.012). The estimated heritability of the AO residual was 0.56 after adjustment for normal and expanded repeats and their interaction. An analysis of tertiles of repeats sizes revealed that the effect of the normal allele is seen among persons with large HD repeat sizes (47-83). These findings suggest that an increase in the size of the normal repeat may mitigate the expression of the disease among HD affected persons with large expanded CAG repeats.

Genetic and functional analyses of FH mutations in multiple cutaneous and uterine leiomyomatosis, hereditary leiomyomatosis and renal cancer, and fumarate hydratase deficiency

Germline mutations of the fumarate hydratase (FH, fumarase) gene are found in the recessive FH deficiency syndrome and in dominantly inherited susceptibility to multiple cutaneous and uterine leiomyomatosis (MCUL). We have previously reported a number of germline FH mutations from MCUL patients. In this study, we report additional FH mutations in MCUL and FH deficiency patients. Mutations can readily be found in about 75% of MCUL cases and most cases of FH deficiency. Some of the more common FH mutations are probably derived from founding individuals. Protein-truncating FH mutations are functionally null alleles. Disease-associated missense FH changes map to highly conserved residues, mostly in or around the enzyme's active site or activation site; we predict that these mutations severely compromise enzyme function. The mutation spectra in FH deficiency and MCUL are similar, although in the latter mutations tend to occur earlier in the gene and, perhaps, are more likely to result in a truncated or absent protein. We have found that not all mutation-carrier parents of FH deficiency children have a strong predisposition to leiomyomata. We have confirmed that renal carcinoma is sometimes part of MCUL, as part of the variant hereditary leiomyomatosis and renal cancer (HLRCC) syndrome, and have shown that these cancers may have either type II papillary or collecting duct morphology. We have found no association between the type or site of FH mutation and any aspect of the MCUL phenotype. Biochemical assay for reduced FH functional activity in the germline of MCUL patients can indicate carriers of FH mutations with high sensitivity and specificity, and can detect reduced FH activity in some patients without detectable FH mutations. We conclude that MCUL is probably a genetically homogeneous tumour predisposition syndrome, primarily resulting from absent or severely reduced fumarase activity, with currently unknown functional consequences for the smooth muscle or kidney cell.

Renormalization and destruction of 1/gamma2 tori in the standard nontwist map

Extending the work of del-Castillo-Negrete, Greene, and Morrison [Physica D 91, 1 (1996); 100, 311 (1997)] on the standard nontwist map, the breakup of an invariant torus with winding number equal to the inverse golden mean squared is studied. Improved numerical techniques provide the greater accuracy that is needed for this case. The new results are interpreted within the renormalization group framework by constructing a renormalization operator on the space of commuting map pairs, and by studying the fixed points of the so constructed operator.

Predictive testing for BRCA1/2: attributes, risk perception and management in a multi-centre clinical cohort

The aim of this multi-centre UK study is to examine the attributes of a cohort offered predictive genetic testing for breast/ovarian cancer predisposition. Participants are adults unaffected with cancer from families with a known BRCA1/2 mutation. This is the first large multi-centre study of this population in the UK. The study evaluates mental health, perceived risk of developing cancer, preferred risk management options, and motivation for genetic testing. Participants were assessed when coming forward for genetic counselling prior to proceeding to genetic testing. Three hundred and twelve individuals, 76% of whom are female, from nine UK centres participated in the study. There are no gender differences in rates of psychiatric morbidity. Younger women (<50 years) are more worried about developing cancer than older women. Few women provide accurate figures for the population risk of breast (37%) or ovarian (6%) cancer but most think that they are at higher risk of developing breast (88%) and ovarian (69%) cancer than the average woman. Cancer related worry is not associated with perceived risk or uptake of risk management options except breast self-examination. The findings indicate that younger women may be particularly vulnerable at the time of the offer of a predictive genetic test.