Sleep disorders in McLeod syndrome: A case series

The protean presentations of XK disease (McLeod syndrome): a case series with new observations and updates on previously reported families

XK disease is a very rare, multi-system disease, which can present with a wide spectrum of symptoms. This disorder can also be identified pre-symptomatically with the incidental detection of serological abnormalities when typing erythrocytes in peripheral blood, or on other routine laboratory testing. Increasing awareness of this disorder and improved access to genetic testing are resulting in increasing identification of affected patients and families. Here we provide updates to some previously-reported families and patients and provide additional clinical details. We also report four new cases with a variety of presentations, one of whom had a novel mutation.

Recent advances in non-Huntington's disease choreas

INTRODUCTION

Chorea is primarily due to an imbalance of basal ganglia output pathways, often due to dysfunction or degeneration of the caudate nucleus and putamen, and can be due to many causes.

METHODS

We reviewed the recent literature to identify newly-recognized causes of chorea, including auto-immune, metabolic, and genetic. We also focused upon developments in mechanisms relating to underlying pathophysiology of certain genetic choreas and advances in therapeutics.

RESULTS

Novel autoantibodies continue to be identified as causes of chorea. Both COVID-19 infection and vaccination are reported to result rarely in chorea, although in some cases causality is not clearly established. Advances in genetic testing continue to find more causes of chorea, and to expand the phenotype of known genetic disorders. Deep brain stimulation can be successful in certain circumstances.

CONCLUSION

Our understanding of mechanisms underlying this movement disorder continues to advance, however much remains to be elucidated.

Polysomnographic findings in the ultra-rare McLeod syndrome: further documentation of sleep apnea as a possible feature

STUDY OBJECTIVES

McLeod syndrome is a very rare multisystemic neurodegenerative disease linked to mutations in the XK gene. It has cardiac, neurologic, and neuromuscular manifestations and shares similarities with Huntington's disease. The aim of this study was to evaluate sleep patterns of patients affected by McLeod syndrome.

METHODS

This retrospective case series of four males who underwent diagnostic polysomnography (mean age 53.8 ± 2.5 years) includes self-reported and objective evaluation of sleep using the Epworth Sleepiness Scale, genetic tests, documentation of clinical course and features, and laboratory-based full-night attended video-polysomnography.

RESULTS

In three out of four patients, an Epworth Sleepiness Scale score ≥ 7 was evident. The average apnea-hypopnea index was 45.0 ± 19.0, with predominantly obstructive phenotype in three patients and predominant central events (central sleep apnea syndrome) in one patient. A significantly increased periodic limb movement index during sleep was observed in all patients. All patients tolerated continuous positive airway pressure or pressure controlled therapy.

CONCLUSIONS

Polysomnography of all patients confirmed sleep apnea syndrome as a feature of McLeod syndrome. Three patients were diagnosed with obstructive sleep apnea and one with central sleep apnea syndrome. In addition, periodic limb movement index was increased in all patients.

CITATION

Dieter M, Kevin P, Tobias V, et al. Polysomnographic findings in the ultra-rare McLeod syndrome: further documentation of sleep apnea as a possible feature. J Clin Sleep Med. 2024;20(3):339-344.

Sleep Disorders in Patients with Choreic Syndromes

PURPOSE OF REVIEW

Patients with different types of choreic syndromes, specially those with Huntington's (HD) and Wilson's (WD) diseases, report frequent sleep complaints. This review focuses on the main findings of studies addressing the sleep features in these diseases, and other less frequent causes of chorea associated with sleep disorders, including a new syndrome described in the last decade associated with IgLON5 antibodies.

RECENT FINDINGS

Patients with HD and WD showed a bad quality of sleep and high frequency of insomnia and excessive daytime somnolence. WD patients also showed high scores on a specific scale for rapid eye movement sleep behavior disorders. HD and WD share decreased sleep efficiency and increased REM sleep latencies, percentage of sleep stage N1, and wake after sleep onset (WASO) among their polysomnographic features. Patients with HD and WD showed a high prevalence of different sleep disorders. Patients with other causes of chorea, including neuroacanthocytosis, parasomnia with sleep breathing disorder associated with antibodies to IgLON5, Sydenham's chorea, and choreic syndromes associated to certain genetic mutations show sleep disorders as well.

Neuroacanthocytosis Syndromes: The Clinical Perspective

The two very rare neurodegenerative diseases historically known as the "neuroacanthocytosis syndromes" are due to mutations of either VPS13A or XK. These are phenotypically similar disorders that affect primarily the basal ganglia and hence result in involuntary abnormal movements as well as neuropsychiatric and cognitive alterations. There are other shared features such as abnormalities of red cell membranes which result in acanthocytes, whose relationship to neurodegeneration is not yet known. Recent insights into the functions of these two proteins suggest dysfunction of lipid processing and trafficking at the subcellular level and may provide a mechanism for neuronal dysfunction and death, and potentially a target for therapeutic interventions.