The 3p21.1-p21.3 Hereditary Vascular Retinopathy Locus Increases the Risk for Raynaud's Phenomenon and Migraine

Part I: Epidemiology, pathophysiology, and clinical considerations of primary and secondary Raynaud's phenomenon

Raynaud's phenomenon (RP) is a relatively common disease with both primary and secondary forms. It is well understood as a vasospastic condition affecting the acral and digital arteries, resulting in characteristic, well-demarcated color changes typically in the hands and feet in response to cold or stress. Secondary RP (SRP) has been described in association with a variety of rheumatologic and nonrheumatologic diseases, environmental exposures, and/or medications. While both primary RP and SRP may impact the quality of life, SRP may lead to permanent and potentially devastating tissue destruction when undiagnosed and untreated. It is therefore crucial for dermatologists to distinguish between primary and secondary disease forms early in clinical evaluation, investigate potential underlying causes, and risk stratify SRP patients for the development of associated autoimmune connective tissue disease. The epidemiology, pathogenesis, and clinical presentation and diagnosis of both forms of RP are described in detail in this review article.

Systemic features of retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations: a monogenic small vessel disease

BACKGROUND

Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a small vessel disease caused by C-terminal truncating TREX1 mutations. The disease is typically characterized by vascular retinopathy and focal and global brain dysfunction. Systemic manifestations have also been reported but not yet systematically investigated.

METHODS

In a cross-sectional study, we compared the clinical characteristics of 33 TREX1 mutation carriers (MC+) from three Dutch RVCL-S families with those of 37 family members without TREX1 mutation (MC-). All participants were investigated using personal interviews, questionnaires, physical, neurological and neuropsychological examinations, blood and urine tests, and brain MRI.

RESULTS

In MC+, vascular retinopathy and Raynaud's phenomenon were the earliest symptoms presenting from age 20 onwards. Kidney disease became manifest from around age 35, followed by liver disease, anaemia, markers of inflammation and, in some MC+, migraine and subclinical hypothyroidism, all from age 40. Cerebral deficits usually started mildly around age 50, associated with white matter and intracerebral mass lesions, and becoming severe around age 60-65.

CONCLUSIONS

Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations is a rare, but likely underdiagnosed, systemic small vessel disease typically starting with vascular retinopathy, followed by multiple internal organ disease, progressive brain dysfunction, and ultimately premature death.

Migraine pathophysiology: lessons from mouse models and human genetics

Migraine is a common, disabling, and undertreated episodic brain disorder that is more common in women than in men. Unbiased genome-wide association studies have identified 13 migraine-associated variants pointing at genes that cluster in pathways for glutamatergic neurotransmission, synaptic function, pain sensing, metalloproteinases, and the vasculature. The individual pathogenetic contribution of each gene variant is difficult to assess because of small effect sizes and complex interactions. Six genes with large effect sizes were identified in patients with rare monogenic migraine syndromes, in which hemiplegic migraine and non-hemiplegic migraine with or without aura are part of a wider clinical spectrum. Transgenic mouse models with human monogenic-migraine-syndrome gene mutations showed migraine-like features, increased glutamatergic neurotransmission, cerebral hyperexcitability, and enhanced susceptibility to cortical spreading depression, which is the electrophysiological correlate of aura and a putative trigger for migraine. Enhanced susceptibility to cortical spreading depression increased sensitivity to focal cerebral ischaemia, and blocking of cortical spreading depression improved stroke outcome in these mice. Changes in female hormone levels in these mice modulated cortical spreading depression susceptibility in much the same way that hormonal fluctuations affect migraine activity in patients. These findings confirm the multifactorial basis of migraine and might allow new prophylactic options to be developed, not only for migraine but potentially also for migraine-comorbid disorders such as epilepsy, depression, and stroke.

Migraine and stroke: "vascular" comorbidity

Several comorbidities are associated to migraine. Recent meta-analyses have consistently demonstrated a relationship between migraine and stroke, which is well-defined for ischemic stroke and migraine with aura (MA), even stronger in females on oral contraceptives or smokers. However, there seems to be no clear-cut association between stroke in migraineurs and the common vascular risk factors, at least in the young adult population. Migraineurs also run an increased risk of hemorrhagic stroke, while the association between migraine and cardiovascular disease remains poorly defined. Another aspect is the relationship between migraine and the presence of silent brain lesions. It has been demonstrated that there is an increased frequency of ischemic lesions in the white matter of migraineurs, especially silent infarcts in the posterior circulation territory in patients with at least 10 attacks per month. Although there is a higher prevalence of patent foramen ovale (PFO) in migraineurs, the relationship between migraine and PFO remains controversial and PFO closure is not a recommended procedure to prevent migraine. As an increased frequency of cervical artery dissections has been observed in migrainous patients, it has been hypothesized that migraine may represent a predisposing factor for cervical artery dissection. There still remains the question as to whether migraine should be considered a true “vascular disease” or if the comorbidity between migraine and cerebrovascular disease may have underlying shared risk factors or pathophysiological mechanisms. Although further studies are required to clarify this issue, current evidence supports a clinical management where MA patients should be screened for other concomitant vascular risk factors and treated accordingly.

Migraine aura pathophysiology: the role of blood vessels and microembolisation

Migraine attacks with auras are sometimes associated with underlying hereditary or acquired cerebrovascular disorders. A unifying pathophysiological explanation linking migraine to these conditions has been difficult to identify. On the basis of genetic and epidemiological evidence, we suggest that changes in blood vessels, hypoperfusion disorders, and microembolisation can cause neurovascular dysfunction and evoke cortical spreading depression, an event that is widely thought to underlie aura symptoms. In fact, recent experimental data have indicated that focal, mild, and transient ischaemia can trigger cortical spreading depression without an enduring tissue signature. Although migraine with aura has many causes (eg, neuronal network excitability), it seems that migraine and stroke might both be triggered by hypoperfusion and could therefore exist on a continuum of vascular complications in a subset of patients who have these hereditary or acquired comorbid vascular conditions.

Genetics of headaches

Insight into the molecular mechanisms involved in primary headaches is important to identify drug targets for improving treatment of patients, but essentially lacking. Genetic research is increasingly successful in pinpointing these mechanisms. Most progress has been made for Familial Hemiplegic Migraine, a rare subtype of migraine with aura. Three genes (CACNA1A, ATP1A2 and SCN1A) have been identified that all encode ion transporters. Cellular and transgenic mouse studies suggest that neuronal hyperexcitability and increased susceptibility to cortical spreading depression, the correlate of migraine aura, are important molecular mechanisms in migraine. Investigating monogenic diseases in which migraine is a prominent feature such as CADASIL, which is caused by mutations in the NOTCH3 gene, can help understanding the pathology of migraine. Candidate gene association studies and linkage studies in the common forms of migraine were less successful. Except for the MTHFR gene no gene variant has been identified yet. Convincingly demonstrated genetic findings in other primary headaches such as cluster headache and tension-type headache are even rarer. However, with current technical possibilities of massive genotyping and international efforts to collect large well-phenotyped patient cohorts, the first gene variants for various primary headache types are likely to be discovered in the coming decade.

Migraine and Genetic and Acquired Vasculopathies

It is remarkable that migraine is a prominent part of the phenotype of several genetic vasculopathies, including cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL), retinal vasculopathy with cerebral leukodystrophy (RVCL) and hereditary infantile hemiparessis, retinal arteriolar tortuosity and leukoencephalopahty (HIHRATL). The mechanisms by which these genetic vasculopathies give rise to migraine are still unclear. Common genetic susceptibility, increased susceptibility to cortical spreading depression (CSD) and vascular endothelial dysfunction are among the possible explanations. The relation between migraine and acquired vasculopathies such as ischaemic stroke and coronary heart disease has long been established, further supporting a role of the (cerebral) blood vessels in migraine. This review focuses on genetic and acquired vasculopathies associated with migraine. We speculate how genetic and acquired vascular mechanisms might be involved in migraine.

Towards a definition of comorbidity in the light of clinical complexity

Clinical complexity encompasses multiple levels, including all the disorders and conditions experienced by a person along cross-sectional and longitudinal contexts, the diversity of severity levels and courses of clinical conditions, but also the plurality of values of people experiencing health problems and seeking help for them. The term comorbidity refers to the association of two distinct diseases in the same individual at a rate higher than expected by chance. Looking systematically to comorbidity represents the main road to approach patients' clinical complexity. Once epidemiologically established through population or community surveys, the study of the comorbidity direction and of the chronological patterns of associated clinical entities may offer relevant information from both a clinical and a scientific point of view. Comorbidity profiles of migraine and tension-type headache offer a paradigmatic example to appraise and highlight headache patient clinical complexity, allowing the conversion of diagnosis from a validated cluster of symptoms to a person-centred clinical diagnosis.

Genetics of migraine: an update with special attention to genetic comorbidity

PURPOSE OF REVIEW

To highlight recent genetic findings in migraine and discuss, new mutations in hemiplegic migraine genes in familial and sporadic cases and relevant candidate gene association studies. Special attention will be given to comorbid diseases of migraine.

RECENT FINDINGS

Familial hemiplegic migraine (FHM) is genetically heterogeneous with mutations in the CACNA1A (FHM1), ATP1A2 (FHM2) and SCN1A (FHM3) genes. Nineteen novel ATP1A2 mutations were identified last year, eleven of them in FHM2 families. A systematic genetic analysis of patients with sporadic hemiplegic migraine revealed five mutations in this gene, which has implications for genetic counselling. The identification of a second FHM3 SCN1A mutation definitely established SCN1A as a migraine gene. The identification of TREX1 mutations in families with retinal vasculopathy and associated diseases such as migraine may provide new insights in migraine pathophysiology.

SUMMARY

Many novel ATP1A2 mutations were identified in patients with familial and sporadic hemiplegic migraine. In sporadic patients, ATP1A2 screening has the highest chance of finding a causal mutation. A second FHM3 mutation definitely established the epilepsy SCN1A gene as a migraine gene. The discovery of genes in monogenic diseases in which migraine is prominent may lead to new insights in the molecular pathways involved in migraine pathophysiology.

Examining the essence of migraine--is it the blood vessel or the brain? A debate

A debate is presented that examines whether it is the blood vessel or the brain that determines the essence of migraine.

Headache, Raynaud's syndrome and serotonin receptor agonists in systemic lupus erythematosus

There are potential concerns regarding serotonin receptor agonists in SLE patients with migraine, particularly patients with concomitant Raynaud's syndrome. We estimated the prevalence of lupus-related headache and Raynaud's syndrome in the Montreal General Hospital SLE clinic cohort and evaluated the relationship between these two variables in multivariable logistic regression models, controlling for age, sex, race, SLE duration and the presence of lupus anticoagulant and antibodies to cardiolipin and beta2 glycoprotein I. We also assessed, through chart review in those individuals with both Raynaud's syndrome and migraine, a history of serotonin receptor agonist use, and any associated worsening vasospasm. Based on Systemic Lupus Activity Measure (SLAM) scores, the cumulative incidence of lupus-related headache in our sample (n = 391) was 46.1%; the prevalence of Raynaud's syndrome was 49.4%. The adjusted odds ratio (OR) for lupus-related headache and Raynaud's syndrome was 1.7 (95% CI 1.1, 2.5). In addition, there was a strong independent relationship between headache and anti-beta2 glycoprotein I antibodies (adjusted OR 5.6 [95% CI 1.8, 17.0]). The data from our chart review suggest that careful use of serotonin receptor agonists in patients with both Raynaud's syndrome and migraines may be undertaken, although caution would necessitate that these agents not be used in individuals with very severe Raynaud's (eg, digital ulcerations, and so on).