CADASIL: extended polymorphisms and mutational analysis of the NOTCH3 gene

Uncovering genetic mimics in multiple sclerosis: A single-center clinical exome sequencing study

Background

Multiple sclerosis (MS) shares clinical/radiological features with several monogenic diseases that can mimic MS.

Objective

We aimed to determine if exome sequencing can identify monogenic diseases in patients diagnosed with MS according to the McDonald criteria thus uncovering them as being misdiagnosed.

Methods

We performed whole exome sequencing in a cohort of 278 patients with MS, clinically or radiologically isolated syndrome without cerebrospinal fluid-specific oligoclonal bands (CSF-OCBs) (n = 228), a positive family history of MS (n = 44), or both (n = 6), thereby focusing on individuals potentially more likely to have underlying monogenic conditions mimicking MS. We prioritized 495 genes associated with monogenic diseases sharing features with MS.

Results

A disease-causing variant in NOTCH3 was identified in one patient without CSF-OCBs, no spinal lesions, with non-response to immunotherapy, and a family history of dementia, thereby converting the diagnosis to cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Moreover, 18 patients (6.5% of total) carried variants of unclear significance.

Conclusion

Monogenic diseases being misdiagnosed as MS seem rare in patients diagnosed with MS according to the McDonald criteria, even in CSF-OCB negative cases. The detected pathogenic NOTCH3 variant emphasizes CADASIL as a rare differential diagnosis and highlights the relevance of genetic testing in selected MS cases with atypical presentations.

Rare neurovascular genetic and imaging markers across neurodegenerative diseases

INTRODUCTION

Cerebral small vessel disease (SVD) is common in patients with cognitive impairment and neurodegenerative diseases such as Alzheimer's and Parkinson's. This study investigated the burden of magnetic resonance imaging (MRI)-based markers of SVD in patients with neurodegenerative diseases as a function of rare genetic variant carrier status.

METHODS

The Ontario Neurodegenerative Disease Research Initiative study included 520 participants, recruited from 14 tertiary care centers, diagnosed with various neurodegenerative diseases and determined the carrier status of rare non-synonymous variants in five genes (ABCC6, COL4A1/COL4A2, NOTCH3/HTRA1).

RESULTS

NOTCH3/HTRA1 were found to significantly influence SVD neuroimaging outcomes; however, the mechanisms by which these variants contribute to disease progression or worsen clinical correlates are not yet understood.

DISCUSSION

Further studies are needed to develop genetic and imaging neurovascular markers to enhance our understanding of their potential contribution to neurodegenerative diseases.

Headache and NOTCH3 Gene Variants in Patients with CADASIL

Autosomal dominant cerebral arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited vascular disease characterized by recurrent strokes, cognitive impairment, psychiatric symptoms, apathy, and migraine. Approximately 40% of patients with CADASIL experience migraine with aura (MA). In addition to MA, CADASIL patients are described in the literature as having migraine without aura (MO) and other types of headaches. Mutations in the NOTCH3 gene cause CADASIL. This study investigated NOTCH3 genetic variants in CADASIL patients and their potential association with headache types. Genetic tests were performed on 30 patients with CADASIL (20 women aged 43.6 ± 11.5 and 10 men aged 39.6 ± 15.8). PCR-HRM and sequencing methods were used in the genetic study. We described three variants as pathogenic/likely pathogenic (p.Tyr189Cys, p.Arg153Cys, p.Cys144Arg) and two benign variants (p.Ala202=, p.Thr101=) in the NOTCH3 gene and also presented the NOTCH3 gene variant (chr19:15192258 G>T), which has not been previously described in the literature. Patients with pathogenic/likely pathogenic variants had similar headache courses. People with benign variants showed a more diverse clinical picture. It seems that different NOTCH3 variants may contribute to the differential presentation of a CADASIL headache, highlighting the diagnostic and prognostic value of headache characteristics in this disease.

Influence of different spectra of NOTCH3 variants on the clinical phenotype of CADASIL - experience from Slovakia

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common hereditary vascular disorder causing ischaemic attacks and strokes in middle-aged adults. Though the clinical spectrum includes some typical symptoms, recognition of the disease, especially at an earlier stage, is very difficult because of the highly variable manifestation and incomplete clinical picture. Characteristic brain MRI findings and the presence of pathogenic variants in the NOTCH3 gene are fundamental for CADASIL diagnosis. In this paper, we provide the first comprehensive report on CADASIL patients from Slovakia. Altogether, we identified 23 different pathogenic variants in 35 unrelated families. In our cohort of patients with clinical suspicion of CADASIL, we found a causal genetic defect and confirmed the diagnosis in 10.2% of cases. We present the case reports with up-to-date unpublished NOTCH3 variants and describe their phenotype-genotype correlation: p.(Cys65Phe), p.(Pro86Leu/Ser502Phe), p.(Arg156*), p.(Cys408Arg), p.(Tyr423Cys), p.(Asp1720His), and p.(Asp1893Thrfs*13). The most frequently described location for pathogenic variants was in exon 4, whereas the most common single variant was p.Arg1076Cys in exon 20. Based on the results of our study, we propose a re-evaluation of the criteria for the selection of patients suitable for NOTCH3 gene analysis. We hereby state that the currently used protocol of a high score requirement is not ideal for assessing molecular analysis, and it will be desirable to be less strict in criteria for genetic testing.

Parkinson's Disease, NOTCH3 Genetic Variants, and White Matter Hyperintensities

BACKGROUND

White matter hyperintensities (WMH) on magnetic resonance imaging may influence clinical presentation in patients with Parkinson's disease (PD), although their significance and pathophysiological origins remain unresolved. Studies examining WMH have identified pathogenic variants in NOTCH3 as an underlying cause of inherited forms of cerebral small vessel disease.

METHODS

We examined NOTCH3 variants, WMH volumes, and clinical correlates in 139 PD patients in the Ontario Neurodegenerative Disease Research Initiative cohort.

RESULTS

We identified 13 PD patients (~9%) with rare (<1% of general population), nonsynonymous NOTCH3 variants. Bayesian linear modeling demonstrated a doubling of WMH between variant negative and positive patients (3.1 vs. 6.9 mL), with large effect sizes for periventricular WMH (d = 0.8) and lacunes (d = 1.2). Negative correlations were observed between WMH and global cognition (r = -0.2).

CONCLUSION

The NOTCH3 rare variants in PD may significantly contribute to increased WMH burden, which in turn may negatively influence cognition. © 2020 International Parkinson and Movement Disorder Society.

Genetic Factors of Cerebral Small Vessel Disease and Their Potential Clinical Outcome

Cerebral small vessel diseases (SVD) have been causally correlated with ischemic strokes, leading to cognitive decline and vascular dementia. Neuroimaging and molecular genetic tests could improve diagnostic accuracy in patients with potential SVD. Several types of monogenic, hereditary cerebral SVD have been identified: cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cathepsin A-related arteriopathy with strokes and leukoencephalopathy (CARASAL), hereditary diffuse leukoencephalopathy with spheroids (HDLS), COL4A1/2-related disorders, and Fabry disease. These disorders can be distinguished based on their genetics, pathological and imaging findings, clinical manifestation, and diagnosis. Genetic studies of sporadic cerebral SVD have demonstrated a high degree of heritability, particularly among patients with young-onset stroke. Common genetic variants in monogenic disease may contribute to pathological progress in several cerebral SVD subtypes, revealing distinct genetic mechanisms in different subtype of SVD. Hence, genetic molecular analysis should be used as the final gold standard of diagnosis. The purpose of this review was to summarize the recent discoveries made surrounding the genetics of cerebral SVD and their clinical significance, to provide new insights into the pathogenesis of cerebral SVD, and to highlight the possible convergence of disease mechanisms in monogenic and sporadic cerebral SVD.

Vascular cognitive impairment associated with NOTCH3 Exon 33 mutation: A case report

RATIONALE

Vascular cognitive impairment (VCI) is a common cause of dementia. Research suggests that hereditary factors (gene mutations) play an important role in the pathogenesis of VCI, and a mutation of the NOTCH3 locus is frequently identified in affected patients. Herein, we report the case of a patient with confirmed VCI associated with a NOTCH3 exon 33 gene mutation and review the relevant VCI literature.

PATIENT CONCERNS

A 48-year-old man presented to our neurology clinic with gradually progressive cognitive impairment.

DIAGNOSES

Brain magnetic resonance imaging revealed multiple punctate hyperintensities in the patient's periventricular white matter. Genetic analysis showed a c.6744C > T, p. Ala2223Val substitution in exon 33 of the NOTCH3 gene. We diagnosed thepatient with VCI secondary to a NOTCH3 gene mutation.

INTERVENTIONS

Donepezil (5 mg) and memantine (5 mg) daily.

OUTCOMES

The patient showed symptom improvement at his 3-month and 6-month follow-up appointments.

LESSONS

This patient may have a new type of mutation that is different from the one seen in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, although it involves a NOTCH3 defect. We propose that the entire NOTCH3 gene should be sequenced in patients with suspected hereditary VCI. This practice could facilitate the discovery of newpathogenic mutations and diseases.

Systematic Review of Cysteine-Sparing NOTCH3 Missense Mutations in Patients with Clinical Suspicion of CADASIL

CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is caused by mutations in the NOTCH3 gene, affecting the number of cysteines in the extracellular domain of the receptor, causing protein misfolding and receptor aggregation. The pathogenic role of cysteine-sparing NOTCH3 missense mutations in patients with typical clinical CADASIL syndrome is unknown. The aim of this article is to describe these mutations to clarify if any could be potentially pathogenic. Articles on cysteine-sparing NOTCH3 missense mutations in patients with clinical suspicion of CADASIL were reviewed. Mutations were considered potentially pathogenic if patients had: (a) typical clinical CADASIL syndrome; (b) diffuse white matter hyperintensities; (c) the 33 NOTCH3 exons analyzed; (d) mutations that were not polymorphisms; and (e) Granular osmiophilic material (GOM) deposits in the skin biopsy. Twenty-five different mutations were listed. Four fulfill the above criteria: p.R61W; p.R75P; p.D80G; and p.R213K. Patients carrying these mutations had typical clinical CADASIL syndrome and diffuse white matter hyperintensities, mostly without anterior temporal pole involvement. Cysteine-sparing NOTCH3 missense mutations are associated with typical clinical CADASIL syndrome and typical magnetic resonance imaging (MRI) findings, although with less involvement of the anterior temporal lobe. Hence, these mutations should be further studied to confirm their pathological role in CADASIL.

The Association Between the Genetic Variants of the NOTCH3 Gene and Ischemic Stroke Risk

Background

Ischemic stroke (IS) is a leading cause of disability and death and NOTCH3 as a gene related with cardiac-cerebral vascular disease plays a vital role in IS development. However, the reports about the effect of genetic variants in NOTCH3 gene on IS are still few.

Material/Methods

In order to explore the association between NOTCH3 polymorphisms and IS, 134 patients with IS and 115 controls were enrolled in this case-control study. Polymerase chain reaction was used to do the genotyping of polymorphisms. The χ² test was performed to evaluate Hardy-Weinberg equilibrium (HWE) in the control group and calculate odds ratio (OR) with corresponding 95% confidence interval (CI) which represented the association intensity of NOTCH3 gene polymorphisms and IS risk.

Results

The genotype frequencies in the control group all confirmed to HWE. TT genotype of 381C>T was associated significantly with IS risk (OR=2.441, 95%CI=1.021–5.837). TC, CC mutant genotypes of 1735T>C had higher frequencies in cases than controls and the difference was significant (P=0.013, 0.041); further, its C allele also increased 0.722 times risk in the case group than controls (OR=1.722, 95%CI=1.166–2.541).

Conclusions

NOTCH3 381C>T and 1735T>C polymorphisms were associated with IS and might be the risk factors for IS development, but not NOTCH3 605C>T polymorphism.

R54C Mutation of NOTCH3 Gene in the First Rungus Family with CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare hereditary stroke caused by mutations in NOTCH3 gene. We report the first case of CADASIL in an indigenous Rungus (Kadazan-Dusun) family in Kudat, Sabah, Malaysia confirmed by a R54C (c.160C>T, p.Arg54Cys) mutation in the NOTCH3. This mutation was previously reported in a Caucasian and two Korean cases of CADASIL. We recruited two generations of the affected Rungus family (n = 9) and found a missense mutation (c.160C>T) in exon 2 of NOTCH3 in three siblings. Two of the three siblings had severe white matter abnormalities in their brain MRI (Scheltens score 33 and 50 respectively), one of whom had a young stroke at the age of 38. The remaining sibling, however, did not show any clinical features of CADASIL and had only minimal changes in her brain MRI (Scheltens score 17). This further emphasized the phenotype variability among family members with the same mutation in CADASIL. This is the first reported family with CADASIL in Rungus subtribe of Kadazan-Dusun ethnicity with a known mutation at exon 2 of NOTCH3. The penetrance of this mutation was not complete during the course of this study.

Notch signaling and ageing

Notch signaling is a master controller of the neural stem cell and neural development maintaining a significant role in the normal brain function. Notch genes are involved in embryogenesis, nervous system, and cardiovascular and endocrine function. On the other side, there are studies representing the involvement of Notch mutations in sporadic Alzheimer disease, other neurodegenerative diseases such as Down syndrome, Pick's and Prion's disease, and CADASIL. This manuscript attempts to present a holistic view of the positive or negative contribution of Notch signaling in the adult brain, and at the same time to present and promote the promising research fields of study.

Migraine genetics: current findings and future lines of research

In the last two decades, migraine research has greatly advanced our current knowledge of the genetic contributions and the pathophysiology of this common and debilitating disorder. Nonetheless, this knowledge still needs to grow further and to translate into more effective treatments. To date, several genes involved in syndromic and monogenic forms of migraine have been identified, allowing the generation of animal models which have significantly contributed to current knowledge of the mechanisms underlying these rare forms of migraine. Common forms of migraine are instead posing a greater challenge, as they may most often stem from complex interactions between multiple common genetic variants, with environmental triggers. This paper reviews our current understanding of migraine genetics, moving from syndromic and monogenic forms to oligogenic/polygenic migraines most recently addressed with some success through genome-wide association studies. Methodological issues in study design and future perspectives opened by biomarker research will also be briefly addressed.

Mutational screening of NOTCH3 gene reveals two novel mutations: complexity of CADASIL diagnosis

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an adult onset hereditary vascular disease with neurological manifestations. The classical clinical course is relentlessly progressive with early transient ischaemic attacks (TIA) or strokes, dementia and finally death in the mid-1960s. The disorder is inherited in an autosomal dominant fashion, with high penetrance and broad variable clinical course even within family. It is caused by mutations in the NOTCH3 gene; all causative mutations result in gain or loss of a cysteine residue within the extracellular domain, with exons 3 and 4 reported as hot spot mutational sites. Mutation analysis of the NOTCH3 gene was performed through direct sequencing of the 2-23 exons containing all EGF-like domains. Patients underwent genetic counselling pre and post testing. Here, we report two novel mutations located in exons 6 and 15 of the NOTCH3 gene; clinical description for the probands and for available relatives is enclosed. No reliable data on incidence or prevalence rates of this disease are available: it is therefore essential that the diagnosis is obtained in all suspected cases through the extensive analysis of the NOTCH3 gene and that all cases are brought to the attention of the scientific community.

Skin and sural nerve biopsies: ultrastructural findings in the first genetically confirmed cases of CADASIL in Serbia

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited vascular disorder caused by Notch3 gene mutations. The main histopathological hallmark is granular osmiophilic material (GOM) deposited in the close vicinity of vascular smooth muscle cells (VSMCs). The authors report the first 7 ultrastructurally and genetically confirmed cases of CADASIL in Serbia. Samples of skin and sural nerve were investigated by transmission electron microscopy. GOM deposits were observed around degenerated VSMCs in all the skin biopsies examined. Sural nerve biopsies revealed severe alterations of nerve fibers, endoneurial blood vessels with GOM deposits, endoneurial fibroblasts, and perineurial myofibroblasts. Total genomic DNA was extracted from peripheral blood leukocytes, and exons 2-6 of the Notch3 gene were amplified by PCR and subsequently sequenced. Four different mutations in exons 2 (Cys65Tyr), 3 (Gly89Cys and Arg90Cys), and 6 (Ala319Cys), which determine the CADASIL disease, were detected among all described patients. A novel missense mutation Gly89Cys involving exon 3 was detected. Due to the difficulties in the determination of the Notch3 mutations, these data suggest that electron microscopic analysis for GOMs in dermal vessel wall provides a rapid and reliable screening method for this disease.

Two novel mutations and a previously unreported intronic polymorphism in the NOTCH3 gene

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disease of small vessel caused by mutations in the NOTCH3 gene (NCBI Gene ID: 4854) located on chromosome 19p13.1. NOTCH3 consists of 33 exons which encode a protein of 2321 amino acids. Exons 3 and 4 were found to be mutation hotspots, containing more than 65% of all CADASIL mutations. We performed direct sequencing on an ABI 3130 Genetic Analyser to screen for mutations and polymorphisms on 300 patients who were clinically suspected to have CADASIL. First, exons 3 and 4 were screened in NOTCH3 and if there were no variations found, then extended CADASIL testing (exons 2, 11, 18 and 19) was offered to patients. Here we report two novel non-synonymous mutations identified in the NOTCH3 gene. The first mutation, located in exon 4 was found in a 49-year-old female and causes an alanine to valine amino acid change at position 202 (605C>T). The second mutation, located in exon 11, was found in a 66-year-old female and causes a cysteine to arginine amino acid change at position 579 (1735T>C). We also report a 46-year-old male with a known polymorphism Thr101Thr (rs3815188) and an unreported polymorphism NM_000435.2:c.679+60G>A observed in intron 4 of the NOTCH3 gene. Although Ala202Ala (rs1043994) is a common polymorphism in the NOTCH3 gene, our reported novel mutation (Ala202Val) causes an amino acid change at the same locus. Our other reported mutation (Cys579Arg) correlates well with other known mutations in NOTCH3, as the majority of the CADASIL-associated mutations in NOTCH3 generally occur in the EGF-like (epidermal growth factor-like) repeat domain, causing a change in the number of cysteine residues. The intronic polymorphism NM_000435.2:c.679+60G>A lies close to the intron-exon boundary and may affect the splicing mechanism in the NOTCH3 gene.

Exome sequencing reveals an unexpected genetic cause of disease: NOTCH3 mutation in a Turkish family with Alzheimer's disease

Alzheimer's disease (AD) is a genetically complex disorder for which the definite diagnosis is only accomplished postmortem. Mutations in 3 genes (APP, PSEN1, and PSEN2) are known to cause AD, but a large number of familial cases do not harbor mutations in these genes and several unidentified genes that contain disease-causing mutations are thought to exist. We performed whole exome sequencing in a Turkish patient clinically diagnosed with Alzheimer's disease from a consanguineous family with a complex history of neurological and immunological disorders and identified a mutation in NOTCH3 (p.R1231C), previously described as causing cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Complete screening of NOTCH3 in a cohort of 95 early onset AD cases and 95 controls did not reveal any additional pathogenic mutations. Although the complex history of disease in this family precluded us to establish segregation of the mutation found with disease, our results show that exome sequencing is a rapid, cost-effective and comprehensive tool to detect genetic mutations, allowing for the identification of unexpected genetic causes of clinical phenotypes. As etiological based therapeutics become more common, this method will be key in diagnosing and treating disease.

NOTCH3 gene mutations in subjects clinically suspected of CADASIL

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited cerebrovascular disease due to mutations involving loss or gain of a cysteine residue in the NOTCH3 gene. A cluster of mutations around exons 3 and 4 was originally reported. Identification of pathogenic mutation is important for diagnostic confirmation of the disease, however genetic counselling and testing of relatives at risk is critical in mutation carriers.

METHODS

Mutation analysis of the NOTCH3 gene was performed through direct sequencing in 140 patients with clinical suspicion of CADASIL. Patients underwent genetic counselling pre and post testing. The 2-23 exons containing all EGF-like domains were screened.

RESULTS

14 familial forms of the disease have been identified with 14 different causative mutations in exons 2, 3, 4, 5, 7, 10, 14, 19, 20 and 22 of the NOTCH3 gene; no pathogenetic mutations have been identified in exons 6 and 8; several genetic variations both in coding as well as in intronic regions were identified too.

CONCLUSIONS

Our data confirm the importance of screening the whole EGF-like domains region of NOTCH3 gene for the molecular diagnosis of CADASIL among the Italian population too. Moreover genetic variants different from loss or gain of a cysteine residue are identified and presented.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy in an Israeli family

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic form of hereditary cerebral microangiopathy, and is caused by over 170 different mutations in the NOTCH3 gene at locus 19p13.1-13.26. We report the first study of familial CADASIL in a 39-year-old Jewish woman and her mother who had died previously. The patient's investigations revealed a normal hemogram with no vascular risk factors or chronic disease. Lumbar puncture was normal. Cranial computed tomography scan revealed bilateral diffuse hypodensities in the subcortical white matter. Cranial magnetic resonance imaging showed hyperintense lesions in the cerebral white matter on T2-weighted images. On electron microscopy, a characteristic granular osmiophilic material was seen in the basement membrane surrounding the pericytes and smooth muscle cells in small-sized and medium-sized vessels. Molecular analysis of the NOTCH3 gene was performed with automatic sequencing of exon 3 and 4 (and intron-exon boundaries) showing a nucleotide c.268C > T substitution, leading to a pathogenic amino acid substitution of p.Arg90Cys, confirming a diagnosis of CADASIL. This mutation was also found in the patient's mother. Although the exact prevalence of CADASIL is not known, this disorder has been reported worldwide, and now including Jews, with a genotype and clinical phenotype similar to that in other ethnic groups.

Association of a Notch 3 gene polymorphism with migraine susceptibility

Introduction: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) shares common symptoms with migraine. Most CADASIL causative mutations occur in exons 3 and 4 of the Notch 3 gene. This study investigated the role of C381T (rs 3815188) and G684A (rs 1043994) single nucleotide polymorphisms (SNP) in exons 3 and 4, respectively, of the Notch 3 gene in migraine.

Results: The first part of the study, in a population of 275 migraineurs and 275 control individuals, found a significant association between the C381T variant and migraine, specifically in migraine without aura (MO) sufferers. The G684A variant was also found to be significantly associated with migraine, specifically in migraine with aura (MA) sufferers. A follow-up study in 300 migraineurs and 300 control individuals did not show replicated association of the C381T variant with migraineurs. However, the G684A variant was again shown to be significantly associated with migraine, specifically with MA.

Conclusion: Further investigation of the G684A variant and the Notch 3 gene is warranted to understand their role in migraine.

Pathophysiology of vascular dementia

The concept of Vascular Dementia (VaD) has been recognized for over a century, but its definition and diagnostic criteria remain unclear. Conventional definitions identify the patients too late, miss subjects with cognitive impairment short of dementia, and emphasize consequences rather than causes, the true bases for treatment and prevention. We should throw out current diagnostic categories and describe cognitive impairment clinically and according to commonly agreed instruments that document the demographic data in a standardized manner and undertake a systematic effort to identify the underlying aetiology in each case. Increased effort should be targeted towards the concept of and criteria for Vascular Cognitive Impairment and Post-Stroke Dementia as well as for genetic factors involved, especially as these categories hold promise for early prevention and treatment.