Leukodystrophies

Genetic investigation of dementias in clinical practice

BACKGROUND

The field of neurodegenerative dementia genetics has advanced significantly over the past two decades, but there are still more to be discovered (such as the gene mutation in some familial forms of dementia).

OBJECTIVE

to provide a brief review of the most recent discoveries regarding monogenic dementia, and covering the most frequent genetic diseases that can cause dementia (neurodegenerative or not).

METHODS

a review of the literature will be carried out.

RESULTS

neurodegenerative dementias, vascular dementias and leukoencephalopathies caused by single pathogenic variants are presented.

CONCLUSION

The spectrum of clinical presentations for most of the genes discussed is wide, and hence genetic testing in clinic should try to cover as many genes as possible.

Existing Evidence for the Repurposing of PARP-1 Inhibitors in Rare Demyelinating Diseases

Simple Summary

Poly (ADP-ribose) polymerase-1 (PARP-1) inhibitors are successful cancer therapeutics that impair DNA repair machinery, leading to an accumulation of DNA damage and consequently cell death. The shared underlying mechanisms driving malignancy and demyelinating disease, together with the success of anticancer drugs as repurposed therapeutics, makes the repurposing of PARP-1 inhibitors for demyelinating diseases a worthy concept to consider. In addition, PARP-1 inhibitors demonstrate notable neuroprotective effects in demyelinating disorders, including multiple sclerosis which is considered the archetypical demyelinating disease.

Abstract

Over the past decade, Poly (ADP-ribose) polymerase-1 (PARP-1) inhibitors have arisen as a novel and promising targeted therapy for breast cancer gene (BRCA)-mutated ovarian and breast cancer patients. Therapies targeting the enzyme, PARP-1, have since established their place as maintenance drugs for cancer. Here, we present existing evidence that implicates PARP-1 as a player in the development and progression of both malignancy and demyelinating disease. These findings, together with the proven clinical efficacy and marketed success of PARP-1 inhibitors in cancer, present the repurposing of these drugs for demyelinating diseases as a desirable therapeutic concept. Indeed, PARP-1 inhibitors are noted to demonstrate neuroprotective effects in demyelinating disorders such as multiple sclerosis and Parkinson’s disease, further supporting the use of these drugs in demyelinating, neuroinflammatory, and neurodegenerative diseases. In this review, we discuss the potential for repurposing PARP-1 inhibitors, with a focus on rare demyelinating diseases. In particular, we address the possible use of PARP-1 inhibitors in examples of rare leukodystrophies, for which there are a paucity of treatment options and an urgent need for novel therapeutic approaches.

Emerging Concepts in Vector Development for Glial Gene Therapy: Implications for Leukodystrophies

Central Nervous System (CNS) homeostasis and function rely on intercellular synchronization of metabolic pathways. Developmental and neurochemical imbalances arising from mutations are frequently associated with devastating and often intractable neurological dysfunction. In the absence of pharmacological treatment options, but with knowledge of the genetic cause underlying the pathophysiology, gene therapy holds promise for disease control. Consideration of leukodystrophies provide a case in point; we review cell type – specific expression pattern of the disease – causing genes and reflect on genetic and cellular treatment approaches including ex vivo hematopoietic stem cell gene therapies and in vivo approaches using adeno-associated virus (AAV) vectors. We link recent advances in vectorology to glial targeting directed towards gene therapies for specific leukodystrophies and related developmental or neurometabolic disorders affecting the CNS white matter and frame strategies for therapy development in future.

Neurogenic Bladder and Acute Kidney Injury in Leukodystrophy

Leukodystrophies are genetic white matter disorders. In the young, they represent an important cause of progressive neurological disability. Impairment of the bladder function may be part of the clinical picture of leukodystrophies. A neurogenic bladder is a dysfunctional urinary bladder caused by a disease of the central or peripheral nervous system involved in the control of micturition. In our patient, leukodystrophy-induced neurogenic bladder and acute kidney injury were revealed. If untreated, a neurogenic bladder can cause renal failure and urinary incontinence. Patients with a neurogenic bladder should be monitored, and management should aim to preserve renal function and achieve social continence.

Inhibitors of Myelination and Remyelination, Bone Morphogenetic Proteins, are Upregulated in Human Neurological Disease

During demyelinating disease such as multiple sclerosis and stroke, myelin is destroyed and along with it, the oligodendrocytes that synthesize the myelin. Thus, recovery is limited due to both interruptions in neuronal transmission as well as lack of support for neurons. Although oligodendrocyte progenitor cells remain abundant in the central nervous system, they rarely mature and form new functional myelin in the diseased CNS. In cell culture and in experimental models of demyelinating disease, inhibitory signaling factors decrease myelination and remyelination. One of the most potent of these are the bone morphogenetic proteins (BMPs), a family of proteins that strongly inhibits oligodendrocyte progenitor differentiation and myelination in culture. BMPs are highly expressed in the dorsal CNS during pre-natal development and serve to regulate dorsal ventral patterning. Their expression decreases after birth but is significantly increased in rodent demyelination models such as experimental autoimmune encephalomyelitis, cuprizone ingestion and spinal cord injury. However, until recently, evidence for BMP upregulation in human disease has been scarce. This review discusses new human studies showing that in multiple sclerosis and other demyelinating diseases, BMPs are expressed by immune cells invading the CNS as well as resident CNS cell types, mostly astrocytes and microglia. Expression of endogenous BMP antagonists is also regulated. Identification of BMPs in the CNS is correlated with areas of demyelination and inflammation. These studies further support BMP as a potential therapeutic target.

Late onset adrenoleukodystrophy: A review related clinical case report

Our objective is to review the initial presentation, evolution, progression, final stage, and images in the follow up of an adult patient who presented an uncommon peroxisomal disease (1/20,000 males) that occurred by ABCD1 gene mutation in the Xq28 chromosome; to bring forward the imaging features (which nowadays is the most useful and accessible diagnostic tool) and clinical presentation of adrenoleukodystrophy in adulthood; to propose a differential diagnosis in aid of a prompt recognition of the disease hereafter from a neurologist approach. In relation of a clinical case we reviewed the literature to correlate the principal findings and evolution of the disease. This thrilling but at the same time unfortunate disease is not only a diagnostic problem is also a therapeutic quest besides all the related familial, labor, and social related problems. The very-long chain fatty acids (VLCFA) accumulation leads to a not completely understood mechanisms that precipitate the specific malfunction of the nervous system and adrenal gland. The initial corticospinal bilateral involvement provokes a spastic paraparesis but with the affection of others pathways multiple manifestations appears, with dementia and finally loss of the most of cortical functions secondary to the white matter affection. Since the hematopoietic stem cell transplantation can be treated with variable results, other treatments, as the Lorenzo's oil, have not been consistent with a substantial improvement of the affected individual. The genetic advice and support to the patient and the family are essentials as well as the screening in individuals at risk before the onset of the disease.

Current Therapeutic Approaches in Leukodystrophies: A Review

Leukodystrophies are a heterogeneous class of genetic diseases affecting the white matter in the central nervous system with a broad range of clinical manifestations and a frequently progressive course. An interest in precision medicine has emerged over the last several decades, and biomedical research in leukodystrophies has made exciting advances along this front through therapeutic target discovery and novel disease model systems. In this review, we discuss current and emerging therapeutic approaches in leukodystrophies, including gene therapy, antisense oligonucleotide therapy, CRISPR/CAS-based gene editing, and cell and stem cell based therapies.