Late onset MELAS with m.3243A > G mutation and its association with aneurysm formation

Causal relationship between mitochondrial-associated proteins and cerebral aneurysms: a Mendelian randomization study

Background

Cerebral aneurysm is a high-risk cerebrovascular disease with a poor prognosis, potentially linked to multiple factors. This study aims to explore the association between mitochondrial-associated proteins and the risk of cerebral aneurysms using Mendelian randomization (MR) methods.

Methods

We used GWAS summary statistics from the IEU Open GWAS project for mitochondrial-associated proteins and from the Finnish database for cerebral aneurysms (uIA, aSAH). The association between mitochondrial-associated exposures and cerebral aneurysms was evaluated using MR-Egger, weighted mode, IVW, simple mode and weighted median methods. Reverse MR assessed reverse causal relationship, while sensitivity analyses examined heterogeneity and pleiotropy in the instrumental variables. Significant causal relationship with cerebral aneurysms were confirmed using FDR correction.

Results

Through MR analysis, we identified six mitochondrial proteins associated with an increased risk of aSAH: AIF1 (OR: 1.394, 95% CI: 1.109-1.752, p = 0.0044), CCDC90B (OR: 1.318, 95% CI: 1.132-1.535, p = 0.0004), TIM14 (OR: 1.272, 95% CI: 1.041-1.553, p = 0.0186), NAGS (OR: 1.219, 95% CI: 1.008-1.475, p = 0.041), tRNA PusA (OR: 1.311, 95% CI: 1.096-1.569, p = 0.003), and MRM3 (OR: 1.097, 95% CI: 1.016-1.185, p = 0.0175). Among these, CCDC90B, tRNA PusA, and AIF1 demonstrated a significant causal relationship with an increased risk of aSAH (FDR q < 0.1). Three mitochondrial proteins were associated with an increased risk of uIA: CCDC90B (OR: 1.309, 95% CI: 1.05-1.632, p = 0.0165), tRNA PusA (OR: 1.306, 95% CI: 1.007-1.694, p = 0.0438), and MRM3 (OR: 1.13, 95% CI: 1.012-1.263, p = 0.0303). In the reverse MR study, only one mitochondrial protein, TIM14 (OR: 1.087, 95% CI: 1.004-1.177, p = 0.04), showed a causal relationship with aSAH. Sensitivity analysis did not reveal heterogeneity or pleiotropy. The results suggest that CCDC90B, tRNA PusA, and MRM3 may be common risk factors for cerebral aneurysms (ruptured and unruptured), while AIF1 and NAGS are specifically associated with an increased risk of aSAH, unrelated to uIA. TIM14 may interact with aSAH.

Conclusion

Our findings confirm a causal relationship between mitochondrial-associated proteins and cerebral aneurysms, offering new insights for future research into the pathogenesis and treatment of this condition.

Major cerebral vessels involvement in patients with MELAS syndrome: Worth a scan? A systematic review

Major cerebral vessels have been proposed as a target of defective mitochondrial metabolism in patients with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes syndrome (MELAS). Cerebral angiographic techniques are not routinely performed in MELAS patients. A systematic literature review was performed to identify studies describing major vessel caliber alterations in MELAS. Twenty-three studies reporting on 46 MELAS patients were included. Alterations in major caliber vessels were present in 59% (27/46) of patients. Dilation occurred in 37% (17/46) of patients, and in 88% (15/17) of them during a stroke-like episode (SLE). Stenosis was reported in 24% (11/46) of patients: 36% (4/11) related to an SLE and 64% (7/11) to dissections or degenerative changes. During an SLE, identification of intracranial vessels dilation or stenosis could be a selection tool for new treatment protocols. Outside SLE, identification of major cerebral vessels dissections and degenerative changes may help to prevent subsequent complications.

Cerebral imaging in adult mitochondrial disorders

OBJECTIVES

Among the organs/tissues affected in mitochondrial disorders (MIDs), the brain is the second most frequently affected. Cerebral imaging may correlate with clinical findings but not necessarily. This review summarises and discusses current knowledge and recent advances concerning cerebral abnormalities on imaging in adult MIDs (≥18y).

METHODS

Systematic literature review.

RESULTS

The most common cerebral abnormalities in imaging in adult MIDs are, as in pediatric MIDs, white matter lesions, grey matter lesions, atrophy, optic atrophy, stroke-like lesions, calcifications, and ischemic stroke. Cerebral lesions may remain stable over years but some may undergo dynamic changes within shorter or longer period of times. Typical dynamic lesions are stroke-like lesions and grey matter lesions in the sense of progression or regression. Since cerebral lesions on imaging may or may not go along with clinical manifestations, it is crucial to screen all MID patients for cerebral involvement, which can be effectively accomplished by application of the MRI.

CONCLUSIONS

Cerebral imaging is of paramount importance for diagnosing and monitoring cerebral involvement in MIDs. Cerebral imaging in MIDs contributes to the understanding of the pathogenesis of cerebral involvement in MIDs.

Investigation of the relationship between non-ketotic hyperglycemia and hemichorea-hemiballism: A case report

RATIONALE

Hemichorea-hemiballism, a rare manifestation of non-ketotic hyperglycemia, characterized by involuntary arrhythmic motions involving one side of the body, results from focal lesions in the contralateral caudate nucleus and putamen. Hyperkinetic disorders can be complications of uncontrolled diabetes mellitus and should not be ignored.

PATIENT CONCERNS

We present the case of a 39-year-old woman who presented to the emergency department with a 3-day history of left-sided hemichorea-hemiballism. She had type 2 diabetes mellitus with poor control and maintenance of regular hemodialysis.

DIAGNOSES

The patient was diagnosed as hyperglycemia, normal ketone body and hemichorea-hemiballism based on laboratory examination, computed tomography (CT) scan, and brain magnetic resonance image (MRI).

INTERVENTIONS

Intensive glycemic control via insulin injection was prescribed for correction of hyperglycemia.

OUTCOMES

The unilateral involuntary movements subsided progressively over four weeks. The patient's hemichorea had completely resolved at the three-month follow-up.

LESSONS

This unusual clinical presentation is often accompanied by severe hyperglycemia. Appropriate blood glycemic control is important. If physicians recognize and provide early treatment for this disease, it is usually treatable and has a good prognosis.

MELAS and macroangiopathy: A case report and literature review

RATIONALE

Mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) are thought to be rarely accompanied by macroangiopathy. We reported a case of MELAS that presented right distal internal carotid arterial (ICA) stenosis and reviewed 12 similar previously reported cases involving intracranial large blood vessels.

PATIENT CONCERNS

A 38-year-old man suffered from recurrent stroke-like episodes (SE) such as alternating hemiparesis (right lesion 3 years ago and current left lesion), cortical blindness and seizure for 3 years, and was previously misdiagnosed as cerebral infarction. Magnetic Resonance Angiography (MRA) and Digital Subtraction Angiography (DSA) revealed right distal ICA stenosis and sparse cortex blood vessels, which were related to the previous SE.

DIAGNOSES

He was diagnosed by genetic screening (a mitochondrial DNA A3243G point mutation) and presence of high lactic acidosis (4.03 mmol/L), which rose to 7.8 mmol/L after exercise.

INTERVENTION

The patient received Coenzyme Q10, vitamin C, L-arginine for 2 weeks and valproic acid sodium (400 mg bid) to prevent seizures till now.

OUTCOMES

He is currently less active and intelligent than his peers, with occasional seizures, and needs family care.

LESSONS

Till date, there are 12 reported cases of MELAS combined with major cerebral arteries abnormalities including stenosis, dissection, occlusion, reversible vasoconstriction, aneurysms, and atherosclerosis. Hence, macroangiopathy in MELAS is not very rare. There is correlation between the affected vessels and the lesions in some cases, but not in others, which may increase the misdiagnosis rate. Hence, mitochondrial diseases cannot be excluded due to concurrent macroangiopathic lesions.