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.

A Case of McLeod's Syndrome Presenting with Severe Decompensated Heart Failure

McLeod's syndrome (MLS) is an X-linked disorder caused by mutations in the XK gene with neurological manifestations as well as cardiomyopathy. This is a case of acute exacerbation of heart failure in a 44-year-old White male with a confirmed diagnosis of MLS, which was managed with guideline-directed medical therapy and placement of an implantable cardioverter defibrillator with recovery in ejection fraction.

Chronic granulomatous disease and McLeod syndrome: Stem cell transplant and transfusion support in a 2-year-old patient—a case report

Chronic granulomatous disease (CGD) with McLeod neuroacanthocytosis syndrome (MLS) is a contiguous gene deletion disorder characterized by defective phagocytic function and decreased Kell antigen expression. CGD cure is achieved through hematopoietic stem cell transplant (HSCT) usually in the peri-pubescent years. The presence of MLS makes peri-transfusion support complex, however. Herein, we present the youngest known case of HSCT for CGD in the setting of MLS. A 2-year-old male patient was diagnosed with CGD plus MLS. Due to the severity of the child’s systemic fungal infection at diagnosis, HSCT was deemed the best treatment option despite his small size and age. A related, matched donor was available, and a unique red blood cell support plan had been implemented. Reduced-intensity conditioning was used to reduce the transplant-related mortality risk associated with myeloablative protocols. The transplant course was uneventful; autologous red blood cell (RBC) transfusion support was successful and allowed for the avoidance of possible antibody formation if allogeneic units had been used. The patient achieved 1-year relapse-free survival. The developed protocols provide a viable path to transplant in the very young, and early transplant to cure could reduce disease-related morbidity.

Yeast as a Model to Find New Drugs and Drug Targets for VPS13-Dependent Neurodegenerative Diseases

Mutations in human VPS13A-D genes result in rare neurological diseases, including chorea-acanthocytosis. The pathogenesis of these diseases is poorly understood, and no effective treatment is available. As VPS13 genes are evolutionarily conserved, the effects of the pathogenic mutations could be studied in model organisms, including yeast, where one VPS13 gene is present. In this review, we summarize advancements obtained using yeast. In recent studies, vps13Δ and vps13-I2749 yeast mutants, which are models of chorea-acanthocytosis, were used to screen for multicopy and chemical suppressors. Two of the suppressors, a fragment of the MYO3 and RCN2 genes, act by downregulating calcineurin activity. In addition, vps13Δ suppression was achieved by using calcineurin inhibitors. The other group of multicopy suppressors were genes: FET4, encoding iron transporter, and CTR1, CTR3 and CCC2, encoding copper transporters. Mechanisms of their suppression rely on causing an increase in the intracellular iron content. Moreover, among the identified chemical suppressors were copper ionophores, which require a functional iron uptake system for activity, and flavonoids, which bind iron. These findings point at areas for further investigation in a higher eukaryotic model of VPS13-related diseases and to new therapeutic targets: calcium signalling and copper and iron homeostasis. Furthermore, the identified drugs are interesting candidates for drug repurposing for these diseases.

Brain F-18 FDG and F-18 FP-CIT PET/CT Findings of c.856_860delCTCTA Mutation McLeod Syndrome

McLeod syndrome is a rare X-linked recessive genetic disorder that is caused by mutations of the XK gene. It is one of the core neuroacanthocytosis syndromes. We report the case of a 67-year-old man who presented to Kyungpook National University Hospital in the Republic of Korea with progressive worsening of generalized chorea and dystonia. He had no recognized family history of neurologic illness. A peripheral blood smear showed increased acanthocytes. His serum creatine kinase levels were 894 U/L. A brain MRI showed atrophy of the bilateral striatal nuclei. An F-18 F-N-(3-fluoropropyl)-2β-carboxymethoxy-3β-(4-iodophenyl) nortropane PET/CT showed moderately decreased dopamine transporter uptake in the putamen and severely decreased uptake in the caudate nucleus. An F-18 fludeoxyglucose PET/CT demonstrated markedly decreased metabolism at the caudate nucleus and the putamen. Whole exome sequencing revealed hemizygous pathogenic mutations of the XK gene (c.856_860delCTCTA;p.Leu286TyrfsTer16). We believe that these findings provide useful information regarding the clinical features of individuals with McLeod syndrome.

McLeod Syndrome in a Commercial Airline Pilot

BACKGROUND: The following case report describes the first known case of McLeod Syndrome in a commercial airline pilot. The case describes a 56-yr-old experienced pilot who showed a slow and subtle decline in cognitive function and muscle control in the cockpit. On further examination, the pilots erratic behavior and movement along with lab abnormalities pointed toward McLeod Syndrome. CASE REPORT: The pilot was recommended for evaluation by his fellow crewmembers due to his fidgetiness, clumsiness, and lack of focus during critical portions of flight. The pilot reported having a long-standing history of elevated CK levels. Further lab investigations revealed acanthocytes on blood smear while neurological evaluation detected chorea. The combination of clinical and laboratory features along with genetic test results were all consistent with McLeod Syndrome. DISCUSSION: The case highlights how subtle behavioral and motor coordination changes can be a warning sign for an underlying progressive neurological disorder that requires further workup and referral. Haas C, Levin D, Milone M, Vardiman-Ditmanson J, Mathers C. McLeod syndrome in a commercial airline pilot. Aerosp Med Hum Perform. 2021; 92(9):734737.

Microembolization from an abdominal aortic aneurysm after thoracic aortic replacement

A 66-year-old man with thoracic and abdominal aortic aneurysm suffered from microembolism in the lower extremities after total arch replacement. He presented with livedo reticularis with palpable peripheral pulses, and the serum creatinine kinase level elevated up to 7,695. The abdominal aortic aneurysm, but not the thoracic aorta, was the origin of this complication. The morphological change of thrombus in the abdominal aorta detected by ultrasonography was the key to the diagnosis. Graft replacement of the abdominal aorta finally resolved his problem.