Universal tumor screening in a population with MSH6- and PMS2-associated Lynch syndrome.

PURPOSE: Universal screening for Lynch syndrome (LS) on resected colorectal carcinomas (CRCs) and endometrial carcinomas (ECs) was implemented in Iceland in 2017 using immunohistochemistry (IHC) for mismatch repair (MMR) proteins. We examined the efficacy of the universal screening algorithm to detect LS and the diagnostic accuracy of MMR IHC by comparing results with a population-based genotype database. METHODS: All patients diagnosed with CRC or EC per the Icelandic Cancer Registry from 2017 to 2019 who had tumor MMR IHC performed were included. Pathology reports and patient charts were reviewed. MMR IHC stains were crossmatched with genotyping results obtained from the deCODE database. RESULTS: IHC staining was done on 404 patients with CRC and 74 patients with EC. A total of 61 (15.1%) patients with CRC and 15 (20.3%) patients with EC were MMR-deficient. MMR IHC had 88.9% sensitivity in identifying patients with LS and a positive predictive value of 10.7%. Only 50% of individuals were appropriately referred for genetic testing, leading to underdiagnosis of LS. CONCLUSION: Universal screening for LS using MMR protein IHC in CRC and EC accurately identified patients appropriate for genetic testing in a population with MSH6 and PMS2 LS predominance. Because of lack of referral to genetic counseling, only 50% of patients with LS were identified through the screening algorithm.

Susceptibility allele-specific loss of miR-1324-mediated silencing of the INO80B chromatin-assembly complex gene in pre-eclampsia.

In humans, the elucidation of the genetics underlying multifactorial diseases such as pre-eclampsia remains complex. Given the current day availability of genome-wide linkage- and expression data pools, we applied pathway-guided genome-wide meta-analysis guided by the premise that the functional network underlying these multifactorial syndromes is under selective genetic pressure. This approach drastically reduced the genomic region of interest, i.e. 2p13 linked with pre-eclampsia in Icelandic families, from 8 679 641 bp (region with linkage) to 45 264 bp (coding exons of prioritized genes) (0.83%). Mutation screening of the candidate genes (n = 13) rapidly reduced the minimal critical region and showed the INO80B gene, encoding a novel winged helix domain (pfam14465) and part of the chromatin-remodeling complex, to be linked to pre-eclampsia. The functional defect in placental cells involved a susceptibility allele-dependent loss-of-gene silencing due to increased INO80B RNA stability as a consequence of differential binding of miR-1324 to the susceptibility allele of rs34174194. This risk allele is located at position 1 in an absolutely conserved 7-mer (UUGUCUG) in the 3-UTR of INO80B immediately downstream of a variant Pumillio Recognition Element (UGUANAAG). These data support that pre-eclampsia genes affect a conserved fundamental mechanism that evolved as a consequence of hemochorial placentation. Functionally, this involves founder-dependent, placentally expressed paralogous genes that regulate an essential trophoblast differentiation pathway but act at different entry points.

COPA syndrome in an Icelandic family caused by a recurrent missense mutation in COPA.

BACKGROUND: Rare missense mutations in the gene encoding coatomer subunit alpha (COPA) have recently been shown to cause autoimmune interstitial lung, joint and kidney disease, also known as COPA syndrome, under a dominant mode of inheritance. CASE PRESENTATION: Here we describe an Icelandic family with three affected individuals over two generations with a rare clinical presentation of lung and joint disease and a histological diagnosis of follicular bronchiolitis. We performed whole-genome sequencing (WGS) of the three affected as well as three unaffected members of the family, and searched for rare genotypes associated with disease using 30,067 sequenced Icelanders as a reference population. We assessed all coding and splicing variants, prioritizing variants in genes known to cause interstitial lung disease. We detected a heterozygous missense mutation, p.Glu241Lys, in the COPA gene, private to the affected family members. The mutation occurred de novo in the paternal germline of the index case and was absent from 30,067 Icelandic genomes and 141,353 individuals from the genome Aggregation Database (gnomAD). The mutation occurs within the conserved and functionally important WD40 domain of the COPA protein. CONCLUSIONS: This is the second report of the p.Glu241Lys mutation in COPA, indicating the recurrent nature of the mutation. The mutation was reported to co-segregate with COPA syndrome in a large family from the USA with five affected members, and classified as pathogenic. The two separate occurrences of the p.Glu241Lys mutation in cases and its absence from a large number of sequenced genomes confirms its role in the pathogenesis of the COPA syndrome.

Compound heterozygous mutations in UBA5 causing early-onset epileptic encephalopathy in two sisters.

BACKGROUND: Epileptic encephalopathies are a group of childhood epilepsies that display high phenotypic and genetic heterogeneity. The recent, extensive use of next-generation sequencing has identified a large number of genes in epileptic encephalopathies, including UBA5 in which biallelic mutations were first described as pathogenic in 2016 (Colin E et al., Am J Hum Genet 99(3):695-703, 2016. Muona M et al., Am J Hum Genet 99(3):683-694, 2016). UBA5 encodes an activating enzyme for a post-translational modification mechanism known as ufmylation, and is the first gene from the ufmylation pathway that is linked to disease. CASE PRESENTATION: We sequenced the genomes of two sisters with early-onset epileptic encephalopathy along with their unaffected parents in an attempt to find a genetic cause for their condition. The sisters, born in 2004 and 2006, presented with infantile spasms at six months of age, which later progressed to recurrent, treatment-resistant seizures. We detected a compound heterozygous genotype in UBA5 in the sisters, a genotype not seen elsewhere in an Icelandic reference set of 30,067 individuals nor in public databases. One of the mutations, c.684G > A, is a paternally inherited exonic splicing mutation, occuring at the last nucleotide of exon 7 of UBA5. The mutation is predicted to disrupt the splice site, resulting in loss-of-function of one allele of UBA5. The second mutation is a maternally inherited missense mutation, p.Ala371Thr, previously reported as pathogenic when in compound heterozygosity with a loss-of-function mutation in UBA5 and is believed to produce a hypomorphic allele. Supportive of this, we have identified three adult Icelanders homozygous for the p.Ala371Thr mutation who show no signs of neurological disease. CONCLUSIONS: We describe compound heterozygous mutations in the UBA5 gene in two sisters with early-onset epileptic encephalopathy. To our knowledge, this is the first description of mutations in UBA5 since the initial discovery that pathogenic biallelic variants in the gene cause early-onset epileptic encephalopathy. We further provide confirmatory evidence that p.Ala371Thr is a hypomorphic mutation, by presenting three adult homozygotes who show no signs of neurological disease.

Iceland-genetic counseling services.

This brief report aims to give an overview of the history and current status of clinical genetics services in Iceland and specific genetic counseling considerations for Iceland's population. Presently, there are two part time medical geneticists and one full time genetic counselor with an MSc education from Cardiff, within the Department of Genetic and Molecular Medicine, based in Iceland's only tertiary healthcare facility, Landspitali, the National University Hospital. An oncologist (20 %) also contributes to the cancer genetic counseling service. In addition, a pediatric medical geneticist has a 25 % appointment at the Children's Hospital. No other health care organization offers genetic counseling, and there are no private genetic counseling services.

Association of Morbus Ledderhose with Dupuytren's contracture.

BACKGROUND: Fibromatous nodules in the sole of the foot are often called Ledderhose disease. It is a benign nodular formation in the plantar aponeurosis, typically at the distal medial border. A lump forms and it can be a few centimeters in diameter. It is frequently seen as an isolated disease, but a relationship to Dupuytren's has been noted in some patients. METHODS: The study was a part of a large cohort study, the Reykjavík study. Men with Dupuytren's disease (n = 122) were invited to follow-up 18 years after the initial observation. An equal number of controls, matched for age and smoking habits, were also invited. A total of 92 Dupuytren's patients and 101 control subjects attended for follow-up and were examined for plantar nodules. Statistical evaluation was carried out using chi-square test and presented as odds ratio (OR) and 95% confidence interval (95% CI). RESULTS: Ledderhose disease was identified in 14 of the 92 (15.2%) men with Dupuytren's disease, while it was only in 4 of the 101 (3.9%) matched controls (OR = 4.35, 95% CI, 1.3-16.7, P < 0.01). Men operated for Dupuytren's disease or with finger contractures were more likely to have plantar nodules than those with only nodules or strings in the palms (OR = 6.1, 95% CI, 1.8-27.1, P < 0.001). The plantar involvement was related to family history of Dupuytren's disease (OR = 3.1, 95% CI, 1.1-8.5, P = 0.02). CONCLUSION: Men with manifestations of finger contractures or who need surgery for Dupuytren's disease are more likely to also develop plantar fibromas. LEVEL OF EVIDENCE: Level III, retrospective comparative series.

A homozygous loss-of-function mutation leading to CYBC1 deficiency causes chronic granulomatous disease.

Mutations in genes encoding subunits of the phagocyte NADPH oxidase complex are recognized to cause chronic granulomatous disease (CGD), a severe primary immunodeficiency. Here we describe how deficiency of CYBC1, a previously uncharacterized protein in humans (C17orf62), leads to reduced expression of NADPH oxidase's main subunit (gp91phox) and results in CGD. Analyzing two brothers diagnosed with CGD we identify a homozygous loss-of-function mutation, p.Tyr2Ter, in CYBC1. Imputation of p.Tyr2Ter into 155K chip-genotyped Icelanders reveals six additional homozygotes, all with signs of CGD, manifesting as colitis, rare infections, or a severely impaired PMA-induced neutrophil oxidative burst. Homozygosity for p.Tyr2Ter consequently associates with inflammatory bowel disease (IBD) in Iceland (P = 8.3 × 10-8; OR = 67.6), as well as reduced height (P = 3.3 × 10-4; -8.5 cm). Overall, we find that CYBC1 deficiency results in CGD characterized by colitis and a distinct profile of infections indicative of macrophage dysfunction.

Fabry Disease in Families With Hypertrophic Cardiomyopathy: Clinical Manifestations in the Classic and Later-Onset Phenotypes.

BACKGROUND: The screening of Icelandic patients clinically diagnosed with hypertrophic cardiomyopathy resulted in identification of 8 individuals from 2 families with X-linked Fabry disease (FD) caused by GLA(α-galactosidase A gene) mutations encoding p.D322E (family A) or p.I232T (family B). METHODS AND RESULTS: Familial screening of at-risk relatives identified mutations in 16 family A members (8 men and 8 heterozygotes) and 25 family B members (10 men and 15 heterozygotes). Clinical assessments, α-galactosidase A (α-GalA) activities, glycosphingolipid substrate levels, and in vitro mutation expression were used to categorize p.D322E as a classic FD mutation and p.I232T as a later-onset FD mutation. In vitro expression revealed that p.D322E and p.I232T had α-GalA activities of 1.4% and 14.9% of the mean wild-type activity, respectively. Family A men had markedly decreased α-GalA activity and childhood-onset classic manifestations, except for angiokeratoma and cornea verticillata. Family B men had residual α-GalA activity and developed FD manifestations in adulthood. Despite these differences, all family A and family B men >30 years of age had left ventricular hypertrophy, which was mainly asymmetrical, and had similar late gadolinium enhancement patterns. Ischemic stroke and severe white matter lesions were more frequent among family A men, but neither family A nor family B men had overt renal disease. Family A and family B heterozygotes had less severe or no clinical manifestations. CONCLUSIONS: Men with classic or later-onset FD caused by GLA missense mutations developed prominent and similar cardiovascular disease at similar ages, despite markedly different α-GalA activities.

Comprehensive population-wide analysis of Lynch syndrome in Iceland reveals founder mutations in MSH6 and PMS2.

Lynch syndrome, caused by germline mutations in the mismatch repair genes, is associated with increased cancer risk. Here using a large whole-genome sequencing data bank, cancer registry and colorectal tumour bank we determine the prevalence of Lynch syndrome, associated cancer risks and pathogenicity of several variants in the Icelandic population. We use colorectal cancer samples from 1,182 patients diagnosed between 2000-2009. One-hundred and thirty-two (11.2%) tumours are mismatch repair deficient per immunohistochemistry. Twenty-one (1.8%) have Lynch syndrome while 106 (9.0%) have somatic hypermethylation or mutations in the mismatch repair genes. The population prevalence of Lynch syndrome is 0.442%. We discover a translocation disrupting MLH1 and three mutations in MSH6 and PMS2 that increase endometrial, colorectal, brain and ovarian cancer risk. We find thirteen mismatch repair variants of uncertain significance that are not associated with cancer risk. We find that founder mutations in MSH6 and PMS2 prevail in Iceland unlike most other populations.

Recommendations for initiation and cessation of enzyme replacement therapy in patients with Fabry disease: the European Fabry Working Group consensus document.

INTRODUCTION: Fabry disease (FD) is a lysosomal storage disorder resulting in progressive nervous system, kidney and heart disease. Enzyme replacement therapy (ERT) may halt or attenuate disease progression. Since administration is burdensome and expensive, appropriate use is mandatory. We aimed to define European consensus recommendations for the initiation and cessation of ERT in patients with FD. METHODS: A Delphi procedure was conducted with an online survey (n = 28) and a meeting (n = 15). Patient organization representatives were present at the meeting to give their views. Recommendations were accepted with ≥75% agreement and no disagreement. RESULTS: For classically affected males, consensus was achieved that ERT is recommended as soon as there are early clinical signs of kidney, heart or brain involvement, but may be considered in patients of ≥16 years in the absence of clinical signs or symptoms of organ involvement. Classically affected females and males with non-classical FD should be treated as soon as there are early clinical signs of kidney, heart or brain involvement, while treatment may be considered in females with non-classical FD with early clinical signs that are considered to be due to FD. Consensus was achieved that treatment should not be withheld from patients with severe renal insufficiency (GFR < 45 ml/min/1.73 m(2)) and from those on dialysis or with cognitive decline, but carefully considered on an individual basis. Stopping ERT may be considered in patients with end stage FD or other co-morbidities, leading to a life expectancy of <1 year. In those with cognitive decline of any cause, or lack of response for 1 year when the sole indication for ERT is neuropathic pain, stopping ERT may be considered. Also, in patients with end stage renal disease, without an option for renal transplantation, in combination with advanced heart failure (NYHA class IV), cessation of ERT should be considered. ERT in patients who are non-compliant or fail to attend regularly at visits should be stopped. CONCLUSION: The recommendations can be used as a benchmark for initiation and cessation of ERT, although final decisions should be made on an individual basis. Future collaborative efforts are needed for optimization of these recommendations.

Increased total mortality and cancer mortality in men with Dupuytren's disease: a 15-year follow-up study.

The aim of the present study was to evaluate the mortality rate and causes of death of individuals with Dupuytren's disease. In 1981/82, as part of The Reykjavík Study, a general health survey, 1297 males were examined for clinical signs of Dupuytren's disease. Based on the clinical evaluation the participants were classified into three groups: (1) those with no signs of Dupuytren's disease were referred to as the reference cohort; (2) those with palpable nodules in the palmar fascia were classified as having stage 1; and (3) those who had contracted fingers or had been operated on due to contractures were classified as having stage 2 of Dupuytren's disease. In 1997, after a 15- year follow-up period, the mortality rate and causes of death were investigated in relation to the clinical findings from 1981/82. Information about causes of death were obtained from the National Icelandic Death Registry and the Icelandic Cancer Registry. During the follow-up period, 21.5% (225/1048) of the reference cohort were deceased compared to 29.9% (55/184) of those with stage 1 and 47.7% (31/65) of those with stage 2 of Dupuytren's disease. When adjusted for age, smoking habits and other possible confounders, individuals with stage 2 of the disease showed increased total mortality [hazard ratio (HR) = 1.6; 95% CI 1.1-2.4]. Cancer deaths were increased (HR = 1.9; CI 1.0-3.6). In contrast, participants with stage 1 of Dupuytren's disease did not show increased mortality. A moderate but non-significant increase in cancer incidence was observed among individuals with stage 2 of Dupuytren's disease (HR = 1.5; 95% CI 0.9-2.4, P = 0.15). The study showed increased total mortality of individuals with Dupuytren's disease stage 2, where 42% of the excess in mortality could be attributed to cancer deaths.

Genetic epidemiologic aspects of gastric cancer in Iceland.

BACKGROUND: Association between gastric cancer and environmental factors (diet and infections) has been established, and genetic changes are well described in adenocarcinomas of the stomach. Less is known about clinical features of hereditary gastric cancer and whether the disease is associated with family clustering. STUDY DESIGN: Family trees of patients diagnosed with gastric cancer in Iceland between 1955 and 1999 were identified in the Genealogical Database of the University of Iceland. All probands with age of onset younger than 60 years were used in the study. Families of all probands (n = 455 men and 161 women) were traced to third degree. Through linkage of the genealogic data obtained by the Icelandic Cancer Registry (between 1955 and 1999), all reported cancers were identified in those families. The expected number of cases was calculated using age-specific population rates in Iceland. RESULTS: A relative risk (RR) of 2.2 (95% confidence interval [CI] = 1.6-3.0) and 1.3 (95% CI = 1.0-1.7) for the gastric cancer risk was observed among 2,846 first- and 8,658 second-degree relatives of male probands. For female probands the corresponding relative risks were 1.6 (95% CI = 1.1-2.6, n = 7,396) and 1.4 (95% CI = 0.9-2.0, n = 2,764). The increased risk was more pronounced for relatives of men and women diagnosed with gastric cancer before the age of 50 years. A minor difference in relative risk was found between relatives of probands who were diagnosed with intestinal type or diffuse type gastric cancer. Fifty-eight families with two or more relatives with cancer were identified. In 32 families 2 relatives with gastric cancer were identified and in 26 families 3 or more relatives had gastric cancer. CONCLUSIONS: Relatives of gastric cancer patients have two- to three-fold increased risk of developing gastric cancer. The risk is elevated for both genders.

Linkage and association studies of IL1B and IL1RN gene polymorphisms in preeclampsia.

OBJECTIVE: To determine whether preeclampsia is either associated with or linked to two polymorphisms in the IL1B gene (IL1B-TaqI and IL1B-511) and one polymorphism in the IL1RN gene (IL1RN-IVS2). METHODS: Genotyping was performed in 150 affected sib-pair families and 104 healthy Dutch blood donors. Genotype and allele frequencies as well as allelic associations were assessed in three groups of unrelated women from these 150 families; 133 with either eclampsia, preeclampsia or the haemolysis, elevated liver enzymes, low platelets (HELLP) syndrome, 101 with preeclampsia only, and 63 with HELLP syndrome only. These frequencies were compared to those in controls. Frequencies of transmitted and nontransmitted haplotypes, inferred from the three polymorphisms, were compared. Allele sharing between affected siblings from all 150 families was assessed by means of multipoint nonparametric affected sib-pair analyses. RESULTS: No significant differences in genotype and allele frequencies were found between the unrelated study groups and controls. No allelic associations were apparent, nor were there differences in frequencies of transmitted and nontransmitted haplotypes within affected families. Excess allele sharing for any of the three polymorphic markers was absent in affected sib-pairs. CONCLUSIONS: None of the IL1B and IL1RN polymorphisms provided evidence for either association or linkage with the risk for (pre)eclampsia/HELLP syndrome, preeclampsia only or HELLP syndrome only.

Searching for preeclampsia genes: the current position.

Although there is substantial evidence that preeclampsia has a genetic background, the complexity of the processes involved and the fact that preeclampsia is a maternal-fetal phenomenon does not make the search for the molecular basis of preeclampsia genes easy. It is possible that the single phenotype 'preeclampsia' in fact should be divided into different sub-groups on genetic or biochemical level. In the present review, the preeclampsia phenotype and its pathophysiologic features are discussed. Family studies and postulated inheritance models are summarized. A systematic overview is given on the numerous candidate gene studies and gene-expression studies performed so far and on the currently available genome-wide scan data. Despite extensive research the molecular genetic basis of preeclampsia remains unclear. Future studies will hopefully enhance our insights in the molecular pathogenesis of preeclampsia.

Ichthyosis prematurity syndrome with separation of fetal membranes and neonatal asphyxia.

Ichthyosis prematurity syndrome (IPS) is a rare inherited skin disorder. Children are born prematurely with thick skin and have been found to develop neonatal asphyxia due to occlusions in the bronchial tree from debris in the amniotic fluid. At 31 weeks of gestation, separation of amniotic and chorionic membranes was identified as well as polyhydramnion. The child was born 2 weeks later, with thickened skin with a granular appearance and required immediate ventilation and intensive care. At 2 years of age, the patient has developed an atopic skin condition with severe itching, recurrent skin infections, food intolerance and periods of wheezing. Prenatal observation of separation of foetal membranes or dense amniotic fluid may be signs of IPS and severe complication immediately after birth.