Germline mismatch repair (MMR) gene analyses from English NHS regional molecular genomics laboratories 1996-2020: development of a national resource of patient-level genomics laboratory records.

OBJECTIVE: To describe national patterns of National Health Service (NHS) analysis of mismatch repair (MMR) genes in England using individual-level data submitted to the National Disease Registration Service (NDRS) by the NHS regional molecular genetics laboratories. DESIGN: Laboratories submitted individual-level patient data to NDRS against a prescribed data model, including (1) patient identifiers, (2) test episode data, (3) per-gene results and (4) detected sequence variants. Individualised per-laboratory algorithms were designed and applied in NDRS to extract and map the data to the common data model. Laboratory-level MMR activity audit data from the Clinical Molecular Genetics Society/Association of Clinical Genomic Science were used to assess early years' missing data. RESULTS: Individual-level data from patients undergoing NHS MMR germline genetic testing were submitted from all 13 English laboratories performing MMR analyses, comprising in total 16 722 patients (9649 full-gene, 7073 targeted), with the earliest submission from 2000. The NDRS dataset is estimated to comprise >60% of NHS MMR analyses performed since inception of NHS MMR analysis, with complete national data for full-gene analyses for 2016 onwards. Out of 9649 full-gene tests, 2724 had an abnormal result, approximately 70% of which were (likely) pathogenic. Data linkage to the National Cancer Registry demonstrated colorectal cancer was the most frequent cancer type in which full-gene analysis was performed. CONCLUSION: The NDRS MMR dataset is a unique national pan-laboratory amalgamation of individual-level clinical and genomic patient data with pseudonymised identifiers enabling linkage to other national datasets. This growing resource will enable longitudinal research and can form the basis of a live national genomic disease registry.

Specific mutations in KRAS codon 12 are associated with worse overall survival in patients with advanced and recurrent colorectal cancer.

BACKGROUND: Activating mutations in KRAS have been suggested as potential predictive and prognostic biomarkers. However, the prognostic impact of specific point mutations remains less clear. This study assessed the prognostic impact of specific KRAS mutations on survival for patients with colorectal cancer. METHODS: Retrospective review of patients KRAS typed for advanced and recurrent colorectal cancer between 2010 and 2015 in a UK Cancer Network. RESULTS: We evaluated the impact of KRAS genotype in 392 patients. Mutated KRAS was detected in 42.9% of tumours. KRAS mutations were more common in moderate vs well-differentiated tumours. On multivariate analysis, primary tumour T stage (HR 2.77 (1.54-4.98), P=0.001), N stage (HR 1.51 (1.01-2.26), P=0.04), curative intent surgery (HR 0.51 (0.34-0.76), P=0.001), tumour grade (HR 0.44 (0.30-0.65), P=0.001) and KRAS mutation (1.54 (1.23-2.12), P=0.005) were all predictive of overall survival. Patients with KRAS codon 12 mutations had worse overall survival (HR 1.76 (95% CI 1.27-2.43), P=0.001). Among the five most common codon 12 mutations, only p.G12C (HR 2.21 (1.15-4.25), P=0.01) and p.G12V (HR 1.69 (1.08-2.62), P=0.02) were predictive of overall survival. CONCLUSIONS: For patients with colorectal cancer, p.G12C and p.G12V mutations in codon 12 were independently associated with worse overall survival after diagnosis.

First report of somatic mosaicism for mutations in STK11 in four patients with Peutz-Jeghers syndrome.

Peutz-Jeghers syndrome (PJS) is an autosomal dominant cancer predisposition syndrome characterised by gastrointestinal polyposis and mucocutaneous pigmentation. Mutations in STK11, a serine-threonine protein kinase, have been associated with PJS in up to 100 % of published series. The hypothesis that a further genetic locus for PJS exists is controversial. No mutations in any other genes have been described in association with PJS. To date, no instances of somatic mosaicism for STK11 have been described. DNA extracted from peripheral lymphocytes and buccal cells was screened by sequence analysis for mutations in STK11. Dosage analysis was undertaken by multiplex ligation-dependent probe amplification (MLPA). Four patients have been shown to have mosaicism in STK11: two had mosaic deletions of specific exons (2-3 and 3-10) of the STK11 gene; one had a mosaic nonsense mutation in exon 5; and one had a mosaic frameshift mutation in exon 8. This report details the first four reported cases of somatic mosaicism for STK11 associated with PJS. This shows that techniques in addition to direct sequencing such as MLPA must be used to assess for large scale genomic deletions in patients meeting clinical diagnostic criteria for PJS. This also adds further weight to the hypothesis of a single genetic locus for PJS.

The variable phenotype of the p.A16V mutation of cationic trypsinogen (PRSS1) in pancreatitis families.

OBJECTIVE: To characterise the phenotypes associated with the p.A16V mutation of PRSS1. DESIGN: Clinical and epidemiological data were collected for any family in which a p.A16V mutation was identified, either referred directly to the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer or via a collaborator. DNA samples were tested for mutations in PRSS1, SPINK1, CFTR and CTRC. PATIENTS: Participants were recruited on the basis of either family history of pancreatitis (acute or chronic) or the results of genetic testing. Families were categorised as having hereditary pancreatitis (HP), idiopathic disease or pancreatitis in a single generation. HP was defined as >or=2 cases in >or=2 generations. Main outcome measures Onset of painful episodes of pancreatitis, death from pancreatic cancer, diagnosis of diabetes mellitus and exocrine pancreatic failure. RESULTS: Ten families with p.A16V mutations were identified (22 affected individuals): six HP families, three with idiopathic disease and one with only a single generation affected. The median age of onset, ignoring non-penetrants, was 10 years (95% CI 5 to 25). There were eight confirmed cases of exocrine failure, four of whom also had diabetes mellitus. There were three pancreatic cancer cases. Two of these were confirmed as p.A16V carriers, only one of whom was affected by pancreatitis. Those with p.A16V pancreatitis were compared to affected individuals with p.R122H, p.N29I and no PRSS1 mutation. No significant differences were proven using logrank or Mann-Whitney U tests. CONCLUSIONS: Penetrance of p.A16V is highly variable and family dependent, suggesting it contributes to multigenic inheritance of a predisposition to pancreatitis.

A reference interval for sweat chloride in infants aged between five and six weeks of age.

BACKGROUND: This study was designed to establish a reference interval for sweat chloride for infants without evidence of cystic fibrosis (CF), aged between 5 wk and 6 wk, a time when sweat testing is an integral part of newborn screening for CF. In addition, we compared the gold standard method of sweat testing (quantitative pilocarpine iontophoresis [QPIT, coulometry]) with an emerging methodology (Macroduct [ISE]). METHODS: This was a prospective study on healthy infants at 5-6 wk of age. Sweat collection was undertaken at home on both outer thigh areas using two methods (QPIT and Macroduct ). The order of testing was randomly assigned. Filter paper samples (QPIT) were analysed using flame photometry and coulometry. Macroduct samples were analysed using ion-selective electrodes (ISE, Abbott Architect c8000, UK). RESULTS: Insufficient sweat was collected on 28 occasions with the QPIT (coulometry) method and on 31 with the Macroduct (ISE) capillary system. We achieved a 92% success rate in undertaking two sweat collections consecutively (n = 177). Sweat chloride concentrations were normally distributed with excellent limits of agreement between the two methods of sweat collection and analysis (n = 150). Median (IQR) sweat chloride was 11.2 mmol/L (8-13) with QPIT (coulometry) method with a 99.5th centile (n = 165) of 24 mmol/L. CONCLUSION: The Macroduct (ISE) capillary sweat collection system is valid in this age group. Sweat chloride concentrations above 30 mmol/L should prompt assessment in a specialist CF centre.

Cystic fibrosis transmembrane conductance regulator ion channel function testing in recurrent acute pancreatitis.

GOALS: To understand the relationship between acute recurrent pancreatitis and cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. BACKGROUND: An emerging number of patients present with a nonclassic phenotype of cystic fibrosis (CF) with partial features or single-organ disease only. The association between the phenotype of recurrent pancreatitis CFTR dysfunction is unclear. METHODS: Patients with idiopathic recurrent pancreatitis were referred for electrophysiologic investigation. RESULTS: Thirty-three patients (18 males) aged 20+/-12 years with recurrent pancreatitis were studied. Three patients had mild asthma and 1 patient had mild ulcerative colitis. There was no family history of CF. All patients had normal imaging of the pancreatic duct by endoscopic retrograde cholangiopancreatography or magnetic resonance cholangiopancreatography. No patient was pancreatic insufficient. Mean sweat chloride values were 41+/-14 meq/L (range: 18 to 64). Nasal potential difference (NPD) measurement was pathologic in 7 patients. Mean basal potential difference in these 7 patients was -33+/-13 mV and there was an abnormal response to chloride-free and isoproterenol solutions. There was no difference in sweat chloride concentration between the 2 groups. Mutation analysis revealed W1282X/5T, D1152H/5T, and W1282X/- in 3 patients with abnormal NPD and 1 W1282X allele was found in 1 patient with normal NPD. CONCLUSIONS: In this series, 21% of patients with recurrent pancreatitis have abnormalities of CFTR function. Patients presenting with recurrent, "idiopathic" pancreatitis require CFTR function testing.

Nemaline myopathy caused by absence of alpha-skeletal muscle actin.

OBJECTIVE: To investigate seven congenital myopathy patients from six families: one French Gypsy, one Spanish Gypsy, four British Pakistanis, and one British Indian. Three patients required mechanical ventilation from birth, five died before 22 months, one is ventilator-dependent, but one, at 30 months, is sitting with minimal support. All parents were unaffected. METHODS: The alpha-skeletal muscle actin gene (ACTA1) was sequenced. Available muscle biopsies were investigated by standard histological and electron microscopic techniques. The expression of various proteins was determined by immunohistochemistry, western blotting, or both. RESULTS: Three homozygous ACTA1 null mutations were identified: p.Arg41X in the French patient, p.Tyr364fsX in the Spanish patient, and p.Asp181fsX10 in all five British patients. An absence of alpha-skeletal muscle actin protein but presence of alpha-cardiac actin was shown in all muscle biopsies examined, with more alpha-cardiac actin in the biopsy from the child with the greatest muscle function. Muscle biopsies from all patients exhibited nemaline bodies whereas three also contained zebra bodies. INTERPRETATION: The seven patients have recessive nemaline myopathy caused by absence of alpha-skeletal muscle actin. The level of retention of alpha-cardiac actin, the skeletal muscle fetal actin isoform, may determine alpha-skeletal muscle actin disease severity. This has implications for possible future therapy.

Increased risk of idiopathic chronic pancreatitis in cystic fibrosis carriers.

Cystic fibrosis (CF) is a recessive disease caused by mutations of the CF transmembrane conductance regulator (CFTR) gene. The risk of idiopathic chronic pancreatitis (ICP) is increased in individuals who have CFTR genotypes containing a CF-causing mutation plus a second pathogenic allele. It is unknown whether the risk of ICP is increased in CF carriers who have one CF-causing mutation plus one normal allele. In this study, 52 sporadic cases of ICP were ascertained through the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer. Individuals with pathogenic cationic trypsinogen mutations were excluded. DNA was comprehensively tested for CFTR mutations using a robotically enhanced, multiplexed, and highly redundant form of single-strand conformation polymorphism (SSCP) analysis followed by DNA sequencing. Fifteen subjects had a total of 18 pathogenic CFTR alleles. Eight subjects had common CF-causing mutations. This group included seven CF carriers in whom the second CFTR allele was normal (4.3 times the expected frequency, P=0.0002). Three subjects had compound heterozygotes genotypes containing two pathogenic alleles (31 times the expected frequency, P<0.0001). A variant allele of uncertain significance (p.R75Q) was detected in eight of the 52 ICP subjects and at a similar frequency (13/96) in random donors. ICP differs from other established CFTR-related conditions in that ICP risk is increased in CF carriers who have one documented normal CFTR allele. Having two CFTR mutations imparts a higher relative risk, while having only one mutation imparts a higher attributable risk.

Genetic polymorphisms and retinopathy of prematurity.

PURPOSE: Retinopathy of prematurity (ROP) is a major problem among very preterm survivors of neonatal intensive care. Neovascularization of the retina is prominent in the proliferative stages of ROP and is under the control of several factors such as vascular endothelial growth factor (VEGF). This study was undertaken on the hypothesis that genetic polymorphisms of VEGF, transforming growth factor (TGF)-beta1, and tumor necrosis factor (TNF)-alpha would occur more frequently in preterm infants with progressive ROP than in those with mild or no disease. METHODS: The frequencies of VEGF -634 G-->C, VEGF *936 C-->T, TNF-alpha -308 G-->A, and TGF-beta -509 C-->T were determined in DNA from 91 infants who had received treatment for threshold ROP and 97 comparison infants. RESULTS: The frequencies of the VEGF *936 C-->T, TNF-alpha -308 G-->A and TGF-beta -509 C-->T polymorphisms were similar in both groups. The distribution of alleles at VEGF -634 was significantly different between the two groups (P = 0.03). Homozygotes for the G allele, associated with higher VEGF production were twice as likely to have threshold ROP. CONCLUSIONS: The progression of ROP to threshold ROP in very preterm infants may be influenced by genetic differences in VEGF production. Future efforts at prevention of threshold ROP may be directed toward blocking excess production of VEGF.

Clinical and genetic characteristics of hereditary pancreatitis in Europe.

BACKGROUND & AIMS: Hereditary pancreatitis is an autosomal dominant disease that is mostly caused by cationic trypsinogen (PRSS1) gene mutations. The aim was to determine phenotype-genotype correlations of families in Europe. METHODS: Analysis of data obtained by the European Registry of Hereditary Pancreatitis and Pancreatic Cancer was undertaken using multilevel proportional hazards modelling. RESULTS: There were 112 families in 14 countries (418 affected individuals): 58 (52%) families carried the R122H, 24 (21%) the N29I, and 5 (4%) the A16V mutation, 2 had rare mutations, and 21 (19%) had no PRSS1 mutation. The median (95% confidence interval [CI]) time to first symptoms for R122H was 10 (8, 12) years of age, 14 (11, 18) years for N29I, and 14.5 (10, 21) years for mutation negative patients (P = 0.032). The cumulative risk (95% CI) at 50 years of age for exocrine failure was 37.2% (28.5%, 45.8%), 47.6% (37.1%, 58.1%) for endocrine failure, and 17.5% (12.2%, 22.7%) for pancreatic resection for pain. Time to resection was significantly reduced for females (P < 0.001) and those with the N29I mutation (P = 0.014). The cumulative risk (95% CI) of pancreatic cancer was 44.0% (8.0%, 80.0%) at 70 years from symptom onset with a standardized incidence ratio of 67% (50%, 82%). CONCLUSIONS: Symptoms in hereditary pancreatitis start in younger patients and endpoints take longer to be reached compared with other forms of chronic pancreatitis but the cumulative levels of exocrine and endocrine failure are much higher. There is an increasingly high risk of pancreatic cancer after the age of 50 years unrelated to the genotype.