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1.
Article in English | MEDLINE | ID: mdl-38696538

ABSTRACT

CONTEXT: Head and neck paragangliomas (HNPGLs) are rare, usually benign, slow-growing tumours arising from neural crest-derived tissue. Definitive management pathways for HNPGLs have yet to be clearly defined. OBJECTIVE: To review our experience of the clinical features and management of these tumours and to analyse outcomes of different treatment modalities. METHODS: Demographic and clinical data were obtained from The Northern Ireland Electronic Care Record (NIECR) as well from a prospectively maintained HNPGL database between January 2011 through December 2023. RESULTS: There were 87 patients; 50 females: 37 males with a mean age of 52.3 ± 14.2 years old (range 17-91 years old). 58.6% (n = 51) of patients had carotid body tumours, 25.2% (n = 22) glomus vagal tumours, 6.8% (n = 6) tumours in the middle ear, 2.2% (n = 2) in the parapharyngeal space and 1.1% (n = 1) in the sphenoid sinus. 5.7% (n = 5) of patients had multifocal disease. The mean tumour size at presentation was 3.2 ± 1.4 cm (range 0.5-6.9 cm). Pathogenic SDHD mutations were identified in 41.3% (n = 36), SDHB in 12.6% (n = 11), SDHC in 2.2% (n = 2) and SDHA in 1.1% (n = 1) of the patients. Overall treatment modalities included surgery alone in 51.7% (n = 45) of patients, radiotherapy in 14.9% (n = 13), observation in 28.7% (n = 25), and somatostatin analogue therapy with octreotide in 4.5% (n = 4) of patients. Factors associated with a significantly higher risk of recurrence included age over 60 years (p = .04), tumour size exceeding 2 cm (p = .03), positive SDHx variants (p = .01), and vagal and jugular tumours (p = .04). CONCLUSION: The majority of our patients underwent initial surgical intervention and achieved disease stability. Our results suggest that carefully selected asymptomatic or medically unfit patients can be safely observed provided lifelong surveillance is maintained. We advocate for the establishment of a UK and Ireland national HNPGL registry, to delineate optimal management strategies for these rare tumours and improve long term outcomes.

2.
Mov Disord ; 39(1): 141-151, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37964426

ABSTRACT

BACKGROUND: The ITPR1 gene encodes the inositol 1,4,5-trisphosphate (IP3 ) receptor type 1 (IP3 R1), a critical player in cerebellar intracellular calcium signaling. Pathogenic missense variants in ITPR1 cause congenital spinocerebellar ataxia type 29 (SCA29), Gillespie syndrome (GLSP), and severe pontine/cerebellar hypoplasia. The pathophysiological basis of the different phenotypes is poorly understood. OBJECTIVES: We aimed to identify novel SCA29 and GLSP cases to define core phenotypes, describe the spectrum of missense variation across ITPR1, standardize the ITPR1 variant nomenclature, and investigate disease progression in relation to cerebellar atrophy. METHODS: Cases were identified using next-generation sequencing through the Deciphering Developmental Disorders study, the 100,000 Genomes project, and clinical collaborations. ITPR1 alternative splicing in the human cerebellum was investigated by quantitative polymerase chain reaction. RESULTS: We report the largest, multinational case series of 46 patients with 28 unique ITPR1 missense variants. Variants clustered in functional domains of the protein, especially in the N-terminal IP3 -binding domain, the carbonic anhydrase 8 (CA8)-binding region, and the C-terminal transmembrane channel domain. Variants outside these domains were of questionable clinical significance. Standardized transcript annotation, based on our ITPR1 transcript expression data, greatly facilitated analysis. Genotype-phenotype associations were highly variable. Importantly, while cerebellar atrophy was common, cerebellar volume loss did not correlate with symptom progression. CONCLUSIONS: This dataset represents the largest cohort of patients with ITPR1 missense variants, expanding the clinical spectrum of SCA29 and GLSP. Standardized transcript annotation is essential for future reporting. Our findings will aid in diagnostic interpretation in the clinic and guide selection of variants for preclinical studies. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.


Subject(s)
Aniridia , Carbonic Anhydrases , Cerebellar Ataxia , Intellectual Disability , Movement Disorders , Spinocerebellar Degenerations , Humans , Cerebellar Ataxia/genetics , Mutation, Missense/genetics , Movement Disorders/complications , Atrophy , Inositol 1,4,5-Trisphosphate Receptors/chemistry , Inositol 1,4,5-Trisphosphate Receptors/genetics , Inositol 1,4,5-Trisphosphate Receptors/metabolism , Carbonic Anhydrases/genetics , Carbonic Anhydrases/metabolism , Intracellular Signaling Peptides and Proteins/genetics
4.
Hum Mol Genet ; 32(22): 3123-3134, 2023 11 03.
Article in English | MEDLINE | ID: mdl-37166351

ABSTRACT

Germline pathogenic variants in two genes encoding the lysine-specific histone methyltransferase genes SETD1A and SETD2 are associated with neurodevelopmental disorders (NDDs) characterized by developmental delay and congenital anomalies. The SETD1A and SETD2 gene products play a critical role in chromatin-mediated regulation of gene expression. Specific methylation episignatures have been detected for a range of chromatin gene-related NDDs and have impacted clinical practice by improving the interpretation of variant pathogenicity. To investigate if SETD1A and/or SETD2-related NDDs are associated with a detectable episignature, we undertook targeted genome-wide methylation profiling of > 2 M CpGs using a next-generation sequencing-based assay. A comparison of methylation profiles in patients with SETD1A variants (n = 6) did not reveal evidence of a strong methylation episignature. A review of the clinical and genetic features of the SETD2 patient group revealed that, as reported previously, there were phenotypic differences between patients with truncating mutations (n = 4, Luscan-Lumish syndrome; MIM:616831) and those with missense codon 1740 variants [p.Arg1740Trp (n = 4) and p.Arg1740Gln (n = 2)]. Both SETD2 subgroups demonstrated a methylation episignature, which was characterized by hypomethylation and hypermethylation events, respectively. Within the codon 1740 subgroup, both the methylation changes and clinical phenotype were more severe in those with p.Arg1740Trp variants. We also noted that two of 10 cases with a SETD2-NDD had developed a neoplasm. These findings reveal novel epigenotype-genotype-phenotype correlations in SETD2-NDDs and predict a gain-of-function mechanism for SETD2 codon 1740 pathogenic variants.


Subject(s)
Chromatin , Neurodevelopmental Disorders , Humans , Chromatin/genetics , DNA Methylation/genetics , Mutation , Neurodevelopmental Disorders/genetics , Genetic Association Studies , Codon
6.
Clin Dysmorphol ; 32(1): 1-6, 2023 Jan 01.
Article in English | MEDLINE | ID: mdl-36503916

ABSTRACT

The Ehlers Danlos syndromes are identified by their connective tissue features and are not rich in dysmorphic handles. Vascular Ehlers Danlos syndrome (vEDS) however, is characterised by a recognisable phenotypic constellation of internal and external dysmorphology. This review charts the paediatric and adult phenotypes of vEDS due primarily to COL3A1 gene variants and the potential recognition of some other EDS subtypes, including COL1A1 and COL25A1 that can present with vEDS-like features, with certain dysmorphic handles as clues to the diagnosis and the adjunct of gene testing in patients presenting with vEDS features.


Subject(s)
Ehlers-Danlos Syndrome, Type IV , Ehlers-Danlos Syndrome , Humans , Phenotype , Ehlers-Danlos Syndrome/diagnosis , Ehlers-Danlos Syndrome/genetics , Genetic Testing
8.
Cancer Prev Res (Phila) ; 15(9): 623-634, 2022 09 01.
Article in English | MEDLINE | ID: mdl-35878732

ABSTRACT

ABSTRACT: The CAPP2 trial investigated the long-term effects of aspirin and resistant starch on cancer incidence in patients with Lynch syndrome (LS). Participants with LS were randomized double-blind to 30 g resistant starch (RS) daily or placebo for up to 4 years. We present long-term cancer outcomes based on the planned 10-year follow-up from recruitment, supplemented by National Cancer Registry data to 20 years in England, Wales, and Finland. Overall, 463 participants received RS and 455 participants received placebo. After up to 20 years follow-up, there was no difference in colorectal cancer incidence (n = 52 diagnosed with colorectal cancer among those randomized to RS against n = 53 on placebo) but fewer participants had non-colorectal LS cancers in those randomized to RS (n = 27) compared with placebo (n = 48); intention-to-treat (ITT) analysis [HR, 0.54; 95% confidence interval (CI), 0.33-0.86; P = 0.010]. In ITT analysis, allowing for multiple primary cancer diagnoses among participants by calculating incidence rate ratios (IRR) confirmed the protective effect of RS against non-colorectal cancer LS cancers (IRR, 0.52; 95% CI, 0.32-0.84; P = 0.0075). These effects are particularly pronounced for cancers of the upper GI tract; 5 diagnoses in those on RS versus 21 diagnoses on placebo. The reduction in non-colorectal cancer LS cancers was detectable in the first 10 years and continued in the next decade. For colorectal cancer, ITT analysis showed no effect of RS on colorectal cancer risk (HR, 0.92; 95% CI, 0.62-1.34; P = 0.63). There was no interaction between aspirin and RS treatments. In conclusion, 30 g daily RS appears to have a substantial protective effect against non-colorectal cancer cancers for patients with LS. PREVENTION RELEVANCE: Regular bowel screening and aspirin reduce colorectal cancer among patients with LS but extracolonic cancers are difficult to detect and manage. This study suggests that RS reduces morbidity associated with extracolonic cancers. See related Spotlight, p. 557.


Subject(s)
Colorectal Neoplasms, Hereditary Nonpolyposis , Colorectal Neoplasms , Aspirin/therapeutic use , Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/epidemiology , Colorectal Neoplasms/prevention & control , Colorectal Neoplasms, Hereditary Nonpolyposis/complications , Follow-Up Studies , Humans , Incidence , Resistant Starch
9.
Int J Gynecol Pathol ; 41(6): 608-614, 2022 Nov 01.
Article in English | MEDLINE | ID: mdl-35077082

ABSTRACT

Sebaceous carcinoma is an uncommon primary cutaneous neoplasm which may be associated with mismatch repair (MMR) abnormalities and sometimes with Muir-Torré syndrome. These neoplasms rarely arise in the ovary within a teratoma/ dermoid cyst. We report a sebaceous carcinoma arising in an ovarian teratoma in a 49-yr old (the 14th case reported in the literature) which exhibited loss of expression of MMR proteins MSH2 and MSH6. A germline mutation c.1102C>T was present in exon 7 of the MSH2 gene, the first report of a germline mutation associated with this tumor type. In reporting this case, we review prior reports of primary ovarian sebaceous carcinoma. We recommend that all sebaceous carcinomas of the ovary undergo immunohistochemistry for MMR proteins for investigation of possible Lynch syndrome.


Subject(s)
Carcinoma , Muir-Torre Syndrome , Teratoma , Female , Humans , MutS Homolog 2 Protein/genetics , MutS Homolog 2 Protein/metabolism , DNA Mismatch Repair/genetics , DNA-Binding Proteins/genetics , Muir-Torre Syndrome/complications , Muir-Torre Syndrome/genetics , Teratoma/genetics , Germ-Line Mutation
10.
Clin Endocrinol (Oxf) ; 96(4): 499-512, 2022 04.
Article in English | MEDLINE | ID: mdl-34558728

ABSTRACT

OBJECTIVE: Phaeochromocytomas and paragangliomas (PPGL) are rare, but strongly heritable tumours. Variants in succinate dehydrogenase (SDH) subunits are identified in approximately 25% of cases. However, clinical and genetic information of patients with SDHC variants are underreported. DESIGN: This retrospective case series collated data from 18 UK Genetics and Endocrinology departments. PATIENTS: Both asymptomatic and disease-affected patients with confirmed SDHC germline variants are included. MEASUREMENTS: Clinical data including tumour type and location, surveillance outcomes and interventions, SDHC genetic variant assessment, interpretation, and tumour risk calculation. RESULTS: We report 91 SDHC cases, 46 probands and 45 non-probands. Fifty-one cases were disease-affected. Median age at genetic diagnosis was 43 years (range: 11-79). Twenty-four SDHC germline variants were identified including six novel variants. Head and neck paraganglioma (HNPGL, n = 30, 65.2%), extra-adrenal paraganglioma (EAPGL, n = 13, 28.2%) and phaeochromocytomas (PCC) (n = 3, 6.5%) were present. One case had multiple PPGLs. Malignant disease was reported in 19.6% (9/46). Eight cases had non-PPGL SDHC-associated tumours, six gastrointestinal stromal tumours (GIST) and two renal cell cancers (RCC). Cumulative tumour risk (95% CI) at age 60 years was 0.94 (CI: 0.79-0.99) in probands, and 0.16 (CI: 0-0.31) in non-probands, respectively. CONCLUSIONS: This study describes the largest cohort of 91 SDHC patients worldwide. We confirm disease-affected SDHC variant cases develop isolated HNPGL disease in nearly 2/3 of patients, EAPGL and PCC in 1/3, with an increased risk of GIST and RCC. One fifth developed malignant disease, requiring comprehensive lifelong tumour screening and surveillance.


Subject(s)
Adrenal Gland Neoplasms , Carcinoma, Renal Cell , Gastrointestinal Stromal Tumors , Kidney Neoplasms , Paraganglioma , Pheochromocytoma , Adrenal Gland Neoplasms/genetics , Female , Germ-Line Mutation/genetics , Humans , Male , Membrane Proteins/genetics , Middle Aged , Paraganglioma/genetics , Paraganglioma/pathology , Pheochromocytoma/genetics , Pheochromocytoma/pathology , Retrospective Studies , Succinate Dehydrogenase/genetics , Succinate Dehydrogenase/metabolism , United Kingdom
11.
Ann Clin Transl Neurol ; 9(1): 4-15, 2022 01.
Article in English | MEDLINE | ID: mdl-34908252

ABSTRACT

OBJECTIVE: A group of genes have been reported to be associated with myopathies with tubular aggregates (TAs). Many cases with TAs still lack of genetic clarification. This study aims to explore the genetic background of cases with TAs in order to improve our knowledge of the pathogenesis of these rare pathological structures. METHODS: Thirty-three patients including two family members with biopsy confirmed TAs were collected. Whole-exome sequencing was performed on 31 unrelated index patients and a candidate gene search strategy was conducted. The identified variants were confirmed by Sanger sequencing. The wild-type and the mutant p.Ala11Thr of ALG14 were transfected into human embryonic kidney 293 cells (HEK293), and western blot analysis was performed to quantify protein expression levels. RESULTS: Eleven index cases (33%) were found to have pathogenic variant or likely pathogenic variants in STIM1, ORAI1, PGAM2, SCN4A, CASQ1 and ALG14. Among them, the c.764A>T (p.Glu255Val) in STIM1 and the c.1333G>C (p.Val445Leu) in SCN4A were novel. Western blot analysis showed that the expression of ALG14 protein was severely reduced in the mutant ALG14 HEK293 cells (p.Ala11Thr) compared with wild type. The ALG14 variants might be associated with TAs in patients with complex multisystem disorders. INTERPRETATION: This study expands the phenotypic and genotypic spectrums of myopathies with TAs. Our findings further confirm previous hypothesis that genes related with calcium signalling pathway and N-linked glycosylation pathway are the main genetic causes of myopathies with TAs.


Subject(s)
Muscle, Skeletal/pathology , Muscular Diseases/genetics , Muscular Diseases/pathology , Adolescent , Adult , Biopsy , Female , HEK293 Cells , Humans , Male , Middle Aged , Muscular Diseases/physiopathology , Pedigree , Exome Sequencing , Young Adult
12.
BMJ ; 374: n2264, 2021 09 16.
Article in English | MEDLINE | ID: mdl-34531251

Subject(s)
Learning , Specialization , Humans
15.
PLoS One ; 15(7): e0233912, 2020.
Article in English | MEDLINE | ID: mdl-32609779

ABSTRACT

This article reports Australia's first confirmed ancient underwater archaeological sites from the continental shelf, located off the Murujuga coastline in north-western Australia. Details on two underwater sites are reported: Cape Bruguieres, comprising > 260 recorded lithic artefacts at depths down to -2.4 m below sea level, and Flying Foam Passage where the find spot is associated with a submerged freshwater spring at -14 m. The sites were discovered through a purposeful research strategy designed to identify underwater targets, using an iterative process incorporating a variety of aerial and underwater remote sensing techniques and diver investigation within a predictive framework to map the submerged landscape within a depth range of 0-20 m. The condition and context of the lithic artefacts are analysed in order to unravel their depositional and taphonomic history and to corroborate their in situ position on a pre-inundation land surface, taking account of known geomorphological and climatic processes including cyclone activity that could have caused displacement and transportation from adjacent coasts. Geomorphological data and radiometric dates establish the chronological limits of the sites and demonstrate that they cannot be later than 7000 cal BP and 8500 cal BP respectively, based on the dates when they were finally submerged by sea-level rise. Comparison of underwater and onshore lithic assemblages shows differences that are consistent with this chronological interpretation. This article sets a foundation for the research strategies and technologies needed to identify archaeological targets at greater depth on the Australian continental shelf and elsewhere, building on the results presented. Emphasis is also placed on the need for legislation to better protect and manage underwater cultural heritage on the 2 million square kilometres of drowned landscapes that were once available for occupation in Australia, and where a major part of its human history must lie waiting to be discovered.


Subject(s)
Archaeology/methods , Native Hawaiian or Other Pacific Islander/history , Paleontology/methods , Australia , Fossils , Geologic Sediments , History, Ancient , Humans , Oceans and Seas , Sea Level Rise , Technology/methods , Western Australia
16.
Hum Mutat ; 41(9): 1615-1628, 2020 09.
Article in English | MEDLINE | ID: mdl-32579715

ABSTRACT

Serine biosynthesis disorders comprise a spectrum of very rare autosomal recessive inborn errors of metabolism with wide phenotypic variability. Neu-Laxova syndrome represents the most severe expression and is characterized by multiple congenital anomalies and pre- or perinatal lethality. Here, we present the mutation spectrum and a detailed phenotypic analysis in 15 unrelated families with severe types of serine biosynthesis disorders. We identified likely disease-causing variants in the PHGDH and PSAT1 genes, several of which have not been reported previously. Phenotype analysis and a comprehensive review of the literature corroborates the evidence that serine biosynthesis disorders represent a continuum with varying degrees of phenotypic expression and suggest that even gradual differences at the severe end of the spectrum may be correlated with particular genotypes. We postulate that the individual residual enzyme activity of mutant proteins is the major determinant of the phenotypic variability, but further functional studies are needed to explore effects at the enzyme protein level.


Subject(s)
Abnormalities, Multiple/genetics , Brain Diseases/genetics , Fetal Growth Retardation/genetics , Genetic Association Studies , Ichthyosis/genetics , Limb Deformities, Congenital/genetics , Microcephaly/genetics , Phosphoglycerate Dehydrogenase/genetics , Transaminases/genetics , Female , Fetus , Humans , Infant, Newborn , Male , Mutation , Serine/biosynthesis
17.
Eur Urol ; 78(4): 494-497, 2020 10.
Article in English | MEDLINE | ID: mdl-32532514

ABSTRACT

A BRCA2 prostate cancer cluster region (PCCR) was recently proposed (c.7914 to 3') wherein pathogenic variants (PVs) are associated with higher prostate cancer (PCa) risk than PVs elsewhere in the BRCA2 gene. Using a prospective cohort study of 447 male BRCA2 PV carriers recruited in the UK and Ireland from 1998 to 2016, we estimated standardised incidence ratios (SIRs) compared with population incidences and assessed variation in risk by PV location. Carriers of PVs in the PCCR had a PCa SIR of 8.33 (95% confidence interval [CI] 4.46-15.6) and were at a higher risk of PCa than carriers of other BRCA2 PVs (SIR = 3.31, 95% CI 1.97-5.57; hazard ratio = 2.34, 95% CI 1.09-5.03). PCCR PV carriers had an estimated cumulative PCa risk of 44% (95% CI 23-72%) by the age of 75 yr and 78% (95% CI 54-94%) by the age of 85 yr. Our results corroborate the existence of a PCCR in BRCA2 in a prospective cohort. PATIENT SUMMARY: In this report, we investigated whether the risk of prostate cancer for men with a harmful mutation in the BRCA2 gene differs based on where in the gene the mutation is located. We found that men with mutations in one region of BRCA2 had a higher risk of prostate cancer than men with mutations elsewhere in the gene.


Subject(s)
Genes, BRCA1 , Prostatic Neoplasms/genetics , Aged , Aged, 80 and over , Cohort Studies , Humans , Incidence , Male , Middle Aged , Mutation , Prospective Studies , Prostatic Neoplasms/epidemiology , Risk Assessment
18.
Lancet ; 395(10240): 1855-1863, 2020 06 13.
Article in English | MEDLINE | ID: mdl-32534647

ABSTRACT

BACKGROUND: Lynch syndrome is associated with an increased risk of colorectal cancer and with a broader spectrum of cancers, especially endometrial cancer. In 2011, our group reported long-term cancer outcomes (mean follow-up 55·7 months [SD 31·4]) for participants with Lynch syndrome enrolled into a randomised trial of daily aspirin versus placebo. This report completes the planned 10-year follow-up to allow a longer-term assessment of the effect of taking regular aspirin in this high-risk population. METHODS: In the double-blind, randomised CAPP2 trial, 861 patients from 43 international centres worldwide (707 [82%] from Europe, 112 [13%] from Australasia, 38 [4%] from Africa, and four [<1%] from The Americas) with Lynch syndrome were randomly assigned to receive 600 mg aspirin daily or placebo. Cancer outcomes were monitored for at least 10 years from recruitment with English, Finnish, and Welsh participants being monitored for up to 20 years. The primary endpoint was development of colorectal cancer. Analysis was by intention to treat and per protocol. The trial is registered with the ISRCTN registry, number ISRCTN59521990. FINDINGS: Between January, 1999, and March, 2005, 937 eligible patients with Lynch syndrome, mean age 45 years, commenced treatment, of whom 861 agreed to be randomly assigned to the aspirin group or placebo; 427 (50%) participants received aspirin and 434 (50%) placebo. Participants were followed for a mean of 10 years approximating 8500 person-years. 40 (9%) of 427 participants who received aspirin developed colorectal cancer compared with 58 (13%) of 434 who received placebo. Intention-to-treat Cox proportional hazards analysis revealed a significantly reduced hazard ratio (HR) of 0·65 (95% CI 0·43-0·97; p=0·035) for aspirin versus placebo. Negative binomial regression to account for multiple primary events gave an incidence rate ratio of 0·58 (0·39-0·87; p=0·0085). Per-protocol analyses restricted to 509 who achieved 2 years' intervention gave an HR of 0·56 (0·34-0·91; p=0·019) and an incidence rate ratio of 0·50 (0·31-0·82; p=0·0057). Non-colorectal Lynch syndrome cancers were reported in 36 participants who received aspirin and 36 participants who received placebo. Intention-to-treat and per-protocol analyses showed no effect. For all Lynch syndrome cancers combined, the intention-to-treat analysis did not reach significance but per-protocol analysis showed significantly reduced overall risk for the aspirin group (HR=0·63, 0·43-0·92; p=0·018). Adverse events during the intervention phase between aspirin and placebo groups were similar, and no significant difference in compliance between intervention groups was observed for participants with complete intervention phase data; details reported previously. INTERPRETATION: The case for prevention of colorectal cancer with aspirin in Lynch syndrome is supported by our results. FUNDING: Cancer Research UK, European Union, MRC, NIHR, Bayer Pharma AG, Barbour Foundation.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Aspirin/therapeutic use , Colorectal Neoplasms, Hereditary Nonpolyposis/prevention & control , Anti-Inflammatory Agents, Non-Steroidal/adverse effects , Aspirin/adverse effects , Colorectal Neoplasms, Hereditary Nonpolyposis/genetics , Double-Blind Method , Follow-Up Studies , Heterozygote , Humans , Intention to Treat Analysis , Life Tables , Medication Adherence , Proportional Hazards Models
20.
Am J Hum Genet ; 106(3): 412-421, 2020 03 05.
Article in English | MEDLINE | ID: mdl-32142645

ABSTRACT

Primary familial brain calcification (PFBC) is a rare neurodegenerative disorder characterized by a combination of neurological, psychiatric, and cognitive decline associated with calcium deposition on brain imaging. To date, mutations in five genes have been linked to PFBC. However, more than 50% of individuals affected by PFBC have no molecular diagnosis. We report four unrelated families presenting with initial learning difficulties and seizures and later psychiatric symptoms, cerebellar ataxia, extrapyramidal signs, and extensive calcifications on brain imaging. Through a combination of homozygosity mapping and exome sequencing, we mapped this phenotype to chromosome 21q21.3 and identified bi-allelic variants in JAM2. JAM2 encodes for the junctional-adhesion-molecule-2, a key tight-junction protein in blood-brain-barrier permeability. We show that JAM2 variants lead to reduction of JAM2 mRNA expression and absence of JAM2 protein in patient's fibroblasts, consistent with a loss-of-function mechanism. We show that the human phenotype is replicated in the jam2 complete knockout mouse (jam2 KO). Furthermore, neuropathology of jam2 KO mouse showed prominent vacuolation in the cerebral cortex, thalamus, and cerebellum and particularly widespread vacuolation in the midbrain with reactive astrogliosis and neuronal density reduction. The regions of the human brain affected on neuroimaging are similar to the affected brain areas in the myorg PFBC null mouse. Along with JAM3 and OCLN, JAM2 is the third tight-junction gene in which bi-allelic variants are associated with brain calcification, suggesting that defective cell-to-cell adhesion and dysfunction of the movement of solutes through the paracellular spaces in the neurovascular unit is a key mechanism in CNS calcification.


Subject(s)
Age of Onset , Alleles , Brain Diseases/genetics , Calcinosis/genetics , Cell Adhesion Molecules/genetics , Genes, Recessive , Adolescent , Adult , Animals , Brain Diseases/diagnostic imaging , Calcinosis/diagnostic imaging , Child , Female , Humans , Male , Mice , Middle Aged , Pedigree
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