Menkes' disease: neurophysiological aspects

A systematic review and evidence-based guideline for diagnosis and treatment of Menkes disease

Menkes disease is a rare X-linked neurodegenerative disorder caused by defect in copper metabolism. Parenteral copper supplementation has been used as a potential disease-modifying treatment of Menkes disease for decades. However, recent evidence suggests its efficacy only when treatment is started within days after birth, which also has important implications related to the techniques that enable early diagnosis. We aim at proposing a guideline for prenatal and neonatal diagnosis and for disease-modifying treatment of Menkes disease, guided by a systematic review of the literature, and built in conjunction with medical experts, methodologists and patient representatives. Thirteen articles were used for our recommendations that were based on GRADE system. Reviewed evidence suggests that prenatal genetic diagnosis in families with previous diagnosis of Menkes disease is feasible; analysis of plasma catecholamine levels is accurate for neonatal diagnosis of Menkes disease; treatment with copper-histidine is effective to increase survival and reduce neurologic burden of the disease if initiated in the neonatal period; and, treatment indication should not be guided by patient's genotype. In conclusion, our guideline can contribute to standardize some aspects of the clinical care of patients with Menkes disease, especially reducing disease burden and mortality and providers' and families' anxiety.

Disorders of metal metabolism

Trace elements are chemical elements needed in minute amounts for normal physiology. Some of the physiologically relevant trace elements include iodine, copper, iron, manganese, zinc, selenium, cobalt and molybdenum. Of these, some are metals, and in particular, transition metals. The different electron shells of an atom carry different energy levels, with those closest to the nucleus being lowest in energy. The number of electrons in the outermost shell determines the reactivity of such an atom. The electron shells are divided in sub-shells, and in particular the third shell has s, p and d sub-shells. Transition metals are strictly defined as elements whose atom has an incomplete d sub-shell. This incomplete d sub-shell makes them prone to chemical reactions, particularly redox reactions. Transition metals of biologic importance include copper, iron, manganese, cobalt and molybdenum. Zinc is not a transition metal, since it has a complete d sub-shell. Selenium, on the other hand, is strictly speaking a nonmetal, although given its chemical properties between those of metals and nonmetals, it is sometimes considered a metalloid. In this review, we summarize the current knowledge on the inborn errors of metal and metalloid metabolism.

Identification of novel ATP7A mutations and prenatal diagnosis in Chinese patients with Menkes disease

Menkes disease (MD) is a fatal X-linked multisystem disease caused by mutations in ATP7A. In this study, clinical and genetic analysis was performed in 24 male MD patients. Development delay, seizures, kinky coarse hair, and dystonia were found in 24, 22, 24, and 24 patients, respectively. Serum ceruloplasmin/copper tested in 19 patients was low. Abnormal classic features of MD presented in the MRI/MRA of 19 patients. Seventeen mutations of ATP7A were identified in 22 patients. Twelve were novel mutations including three small deletion/insertion, one missense mutation, two nonsense mutations, three splicing-site mutations, and three gross deletions. Twenty-two patients were genetically diagnosed; neither point mutation nor deletion/duplication was found in two of them. c.2179G > A found in five patients might be a hot-spot mutation. Prenatal molecular diagnosis was performed for five unrelated fetuses (1 female and 4 male), which found four fetuses to be wild type and one male carried the same mutation as the proband. This study of the largest sample of Chinese MD patients examined to date discovered the unique phenotype and genotype spectrum in Chinese patients with 12 novel mutations of ATP7A, and that c.2179G > A might be a hot-spot mutation in MD patients. Five successful prenatal diagnosis contributed important information for MD families.

Menkes disease: what a multidisciplinary approach can do

Disorders of copper homeostasis are currently recognized across the life span. Their recognition and links to human disease have spanned several decades, beginning with the recognition of a degenerative disorder in the offspring of sheep grazing in copper-deficient pastures, through to the description of infants suffering from a progressive neurodegenerative disorder characterized by epileptic seizures, developmental regression, failure to thrive, and an unusual hair quality (giving the condition its distinctive label of “kinky hair disease”). In this review, we trace the historical background and describe the biochemistry and physiology of copper metabolism and transport, inheritance patterns, molecular genetics, and genotype–phenotype correlations based on current understanding of the disorder. It is clear from the clinical presentations and variants that disorders of copper homeostasis include phenotypes ranging from mild occipital horn syndrome to intermediate and severe forms of classical Menkes disease. The symptoms involve multiple organ systems such as brain, lung, gastrointestinal tract, urinary tract, connective tissue, and skin. A multisystem disorder needs a multidisciplinary approach to care, as treatment interventions permit longer survival for some individuals. Animal models have been developed to help screen treatment options and provide a better understanding of these disorders in the laboratory. Finally, we propose a multidisciplinary approach to promote continued research (both basic and clinical) to improve survival, quality of life, and care for these conditions.

Epilepsy in children with Menkes disease: a systematic review of literature

Menkes disease is a lethal multisystemic disorder of copper metabolism characterized by connective tissue abnormalities, progressive neurodegeneration and peculiar "kinky hair." Epilepsy is one of the main clinical features of this disease but it has been described in detail by only a few authors. Most patients develop seizures from 2 to 3 months of age, accompanied by a neurodevelopmental regression. The history of epilepsy is usually characterized by 3 stages: an early stage with focal clonic seizures and status epilepticus, an intermediate stage with infantile spasms, and a late stage with multifocal, myoclonic, and tonic seizures. At the onset, epilepsy can be controlled with anticonvulsant therapy, whereas with the progression of disease, it becomes extremely resistant to all antiepileptic drugs. In this article, we analyze clinical and electroencephalographic (EEG) characteristics of epilepsy in patients with this syndrome.

Epilepsy in Menkes disease: an electroclinical long-term study of 28 patients

BACKGROUND

Epilepsy is a frequent and severe feature of Menkes disease (MD) but only few studies described the long-term evolution of these children. We report a series of 28 epileptic MD patients, with clinical characteristics, EEG abnormalities, brain malformations and long-term outcome.

METHODS

EEG, clinical characteristics and neuroimaging features in 28 MD patients were analyzed at the onset of epilepsy and after long-term follow-up (at least 4 years). We subdivided the patients into two groups: Group 1, 16 patients who received a subcutaneous copper-histidine treatment, and Group 2 including 12 patients who did not get any therapies.

RESULTS

The large majority of our patients presented at the onset of epilepsy focal seizures (FS) and infantile spasms (IS). Five patients had recurrent status epilepticus (SE). During the follow-up, patients showed multiple seizure types: 6 patients had generalized tonic clonic seizures (GCT), 6 patients presented IS, 10 children had FS, 11 had myoclonic jerks and 3 had SE. Therapy with various antiepileptic drugs had poor efficacy, except in three patients who showed seizure disappearance with consequent discontinuation of antiepileptic therapy. There was no difference of neurological outcome among the two groups analyzed.

CONCLUSIONS

Epilepsy in MD is a difficult to treat problem. At the onset, the most frequent type of seizures are FC and IS; in the next months, other kinds of seizures can appear. Many children are drug resistant. Institution of replacement therapy with copper-histidine seems to be not beneficial for epilepsy.

Electro-clinical features and magnetic resonance imaging correlates in Menkes disease

BACKGROUND

Epilepsy is an early and important feature in Menkes disease (MD), an X-linked recessive neurodegenerative disorder of childhood with defect in copper metabolism. There are only few reports on the electro-clinical and magnetic resonance imaging correlates in Menkes disease. The current study describes the electro-clinical features in MD in relation with the structural findings on MRI.

PATIENTS AND METHODS

Six patients from five families were evaluated between 2005 and 2011. Their diagnosis was based on the characteristic morphological features, microscopic evidence of pili torti and low copper and ceruloplasmin levels. All the patients underwent MRI and EEG as part of the evaluation.

RESULTS

All patients had classical form of MD with typical morphological features. All but one patient had refractory seizures. Seizure types included multifocal clonic seizures (n=3), myoclonic jerks (n=4) and tonic spasms (n=1). EEG was markedly abnormal in all except in the patient without clinical seizures. While focal epileptiform discharges predominated before six months of age modified hypsarrhythmia was characteristically noted thereafter. MR Imaging revealed abnormalities in all patients, with cerebral atrophy and delayed myelination being the most common observations. Other features noted were subdural effusion (n=3), leukoencephalopathy (n=3) and basal ganglia signal changes (n=1). Follow up imaging in three patients showed resolution of white matter signal intensity changes.

CONCLUSIONS

Electro-clinical features in Menkes disease are age dependent and evolve sequentially. White matter changes coincided with acute exacerbation of seizures. There was fair correlation between the electro-clinical features and structural findings on MRI.

Inborn errors of copper metabolism

Two copper-transporting ATPases are essential for mammalian copper homeostasis: ATP7A, which mediates copper uptake in the gastrointestinal tract and copper delivery to the brain, and ATP7B, which mediates copper excretion by the liver into bile. Mutations in ATP7A may cause three distinct X-linked conditions in infants, children, or adolescents: Menkes disease, occipital horn syndrome (OHS), and a newly identified allelic variant restricted to motor neurons called X-linked distal hereditary motor neuropathy. These three disorders show variable neurological findings and ages of onset. Menkes disease presents in the first several months of life with failure to thrive, developmental delay, and seizures. OHS features more subtle developmental delays, dysautonomia, and connective tissue abnormalities beginning in early childhood. ATP7A-related distal motor neuropathy presents even later, often not until adolescence or early adulthood, and involves a neurological phenotype that resembles Charcot-Marie-Tooth disease, type 2. These disorders may be treatable through copper replacement or ATP7A gene therapy. In contrast, mutations in ATP7B cause a single known phenotype, Wilson disease, an autosomal recessive trait that results from copper overload rather than deficiency. Dysarthria, dystonia, tremor, gait abnormalities, and psychiatric problems may be presenting symptoms, at ages from 10 to 40 years. Excellent treatment options exist for Wilson disease, based on copper chelation. In the past 2 years (2012-2013), three new autosomal recessive copper metabolism conditions have been recognized: 1) Huppke-Brendel syndrome caused by mutations in an acetyl CoA transporter needed for acetylation of one or more copper proteins, 2) CCS deficiency caused by mutations in the copper chaperone to SODI, and 3) MEDNIK syndrome, which revealed that mutations in the σ1A subunit of adaptor protein complex 1 (AP-1) have detrimental effects on trafficking of ATP7A and ATP7B.

Menkes disease and infantile epilepsy

OBJECTIVES

Menkes disease, an X linked recessive neurodegenerative disorder, results from a mutation in the gene coding for the copper transporting ATPase (ATP7A). Epilepsy is a major clinical feature of this disorder. We describe the clinical presentation, evolution of epilepsy and explore the biological underpinnings of epileptogenesis in Menkes disease.

METHODS

Longitudinal case study illustrating the natural history of epilepsy and results of subcutaneous cupric chloride supplementation in a patient with Menkes disease and literature review.

RESULTS

The onset and evolution of epilepsy in Menkes disease is marked by different stages. Early presentations typically involve focal seizures, with progression to epileptic spasms and a chronic late stage of epilepsy characterized by tonic seizures, myoclonic jerks, and multifocal epileptiform activity on the EEG. Morphological correlates in the brain include evidence of atrophy of grey matter, ventriculomegaly, tortuous intracranial vasculature, and white matter signal changes consistent with loss of myelin and axons. The presence of significant lactic acidosis in brain and cerebrospinal fluid suggests widespread disturbance in oxidative metabolism. Molecular consequences of the pathogenic ATP7A gene mutation lead to impairment in copper transport, which in turn causes deficiencies of key copper containing enzymes (dopamine β hydroxylase and cytochrome c oxidase). Microarray studies suggest widespread effects in dysregulation of genes involved in cellular responses to oxidative stress, ribosomal translation, signal transduction, mitochondrial function, and immune responses. Impairment of copper mediated NMDA receptor function further enhances neuronal excitability, excitotoxic neuronal injury, setting up a cascade that creates conditions for epileptogenesis to follow.

CONCLUSION

Neurological manifestations are likely related to perturbations in copper dependent enzymatic pathways involved in neurotransmitter and energy metabolism. Early diagnosis and institution of copper supplementation has been shown to be beneficial particularly in patients with residual ATP7A activity.

ATP7A-related copper transport diseases-emerging concepts and future trends

This Review summarizes recent advances in understanding copper-transporting ATPase 1 (ATP7A), and examines the neurological phenotypes associated with dysfunction of this protein. Involvement of ATP7A in axonal outgrowth, synapse integrity and neuronal activation underscores the fundamental importance of copper metabolism to neurological function. Defects in ATP7A cause Menkes disease, an infantile-onset, lethal condition. Neonatal diagnosis and early treatment with copper injections enhance survival in patients with this disease, and can normalize clinical outcomes if mutant ATP7A molecules retain small amounts of residual activity. Gene replacement rescues a mouse model of Menkes disease, suggesting a potential therapeutic approach for patients with complete loss-of-function ATP7A mutations. Remarkably, a newly discovered ATP7A disorder-isolated distal motor neuropathy-has none of the characteristic clinical or biochemical abnormalities of Menkes disease or its milder allelic variant occipital horn syndrome (OHS), instead resembling Charcot-Marie-Tooth disease type 2. These findings indicate that ATP7A has a crucial but previously unappreciated role in motor neuron maintenance, and that the mechanism underlying ATP7A-related distal motor neuropathy is distinct from Menkes disease and OHS pathophysiology. Collectively, these insights refine our knowledge of the neurology of ATP7A-related copper transport diseases and pave the way for further progress in understanding ATP7A function.

Molecular correlates of epilepsy in early diagnosed and treated Menkes disease

Epilepsy is a major feature of Menkes disease, an X-linked recessive infantile neurodegenerative disorder caused by mutations in ATP7A, which produces a copper-transporting ATPase. Three prior surveys indicated clinical seizures and electroencephalographic (EEG) abnormalities in a combined 27 of 29 (93%) symptomatic Menkes disease patients diagnosed at 2 months of age or older. To assess the influence of earlier, presymptomatic diagnosis and treatment on seizure semiology and brain electrical activity, we evaluated 71 EEGs in 24 Menkes disease patients who were diagnosed and treated with copper injections in early infancy (≤6 weeks of age), and whose ATP7A mutations we determined. Clinical seizures were observed in only 12.5% (3/24) of these patients, although 46% (11/24) had at least one abnormal EEG tracing, including 50% of patients with large deletions in ATP7A, 50% of those with small deletions, 60% of those with nonsense mutations, and 57% of those with canonical splice junction mutations. In contrast, five patients with mutations shown to retain partial function, either via some correct RNA splicing or residual copper transport capacity, had neither clinical seizures nor EEG abnormalities. Our findings suggest that early diagnosis and treatment improve brain electrical activity and decrease seizure occurrence in classical Menkes disease irrespective of the precise molecular defect. Subjects with ATP7A mutations that retain some function seem particularly well protected by early intervention against the possibility of epilepsy.

Menkes syndrome presenting as myoclonic seizures: neuroimaging and EEG observations

The authors report an 11-month-old boy with Menkes kinky hair disease who presented with global delay in acquiring milestones and repeated myoclonic jerks. He had scanty, hypopigmented scalp hairs with steely wool-like texture and intervening zones of alopecia. There was low serum ceruloplasmin (5 mg/dL) and copper (24.2 microg/dL). Neuroimaging of the brain revealed marked cerebral atrophy and significant delayed myelination. Magnetic resonance angiography showed tortuous cerebral and neck blood vessels. There was poor therapeutic response to symptomatic treatment.

Epilepsy in Menkes Disease: Analysis of Clinical Stages

PURPOSE

Epilepsy is one of the main features of Menkes disease (MD), although it is not described in depth. To determine the spectrum of epilepsy, we studied its main characteristics.

METHODS

Based on clinical charts, we retrospectively analyzed the evolution of electroclinical features of 12 patients with confirmed MD.

RESULTS

Epilepsy could be divided into three periods: (a) an early stage (median age, 3 months), characterized by focal clonic status epilepticus, usually triggered by fever (10 patients). Ictal EEG showed runs of slow spike-waves and slow waves in the posterior regions, and interictal EEG multifocal and polymorphic slow waves (three cases), or mixed slow spike-waves and slow waves (seven cases). Partial seizure control was obtained in nine patients during 5.9 months; (b) an intermediate stage (median age, 10 months) with intractable infantile spasms (11 patients) in which interictal EEG demonstrated modified hypsarrhythmia (seven cases), diffuse irregular slow waves and spike-waves (four cases). Six patients died at the median age of 15 months; and (c) a late stage in the six remaining patients (median age, 25 months), with multifocal seizures, tonic spasms, and myoclonus in four patients, whereas two patients became seizure free. Interictal EEG showed multifocal high-amplitude activity, mixed with irregular slow waves in all six cases. These patients died at the median age of 3.6 years.

CONCLUSIONS

Based on a relatively large series of MD patients with a quite prolonged survival, we individualized three successive periods in the course of epilepsy: early focal status, then infantile spasms, and then myoclonic and multifocal epilepsy after age 2 years.

Menkes' syndrome: ophthalmic findings

PURPOSE

To report the prevalence and clinical significance of ocular findings in 20 patients with Menkes' syndrome recruited for a clinical trial at the National Institute of Child Health and Human Development (NICHHD).

DESIGN

Retrospective observational case series.

PARTICIPANTS

Twenty patients with Menkes' syndrome enrolled in a clinical trial at the NICHHD, who underwent ophthalmic evaluation at the National Eye Institute from 1990 through 1997.

METHODS

Review of clinical ophthalmic examination records, photographs, and visual evoked potential recordings.

MAIN OUTCOME MEASURES

Prevalence of ophthalmic signs of unusual frequency in patients with Menkes' syndrome.

RESULTS

There was a high prevalence of very poor visual acuity (8 patients), myopia at 21 months old or younger (5 of 9 patients this age who underwent cycloplegic refraction), strabismus (11 of 18 patients whose motility was evaluated), blue irides (15 of 16 patients whose iris color was documented), iris stromal hypoplasia and bilateral peripheral transillumination (7 and 3 patients, respectively), peripheral retinal hypopigmentation (7 of 18 patients whose retinal periphery was noted at the initial examination), and aberrant eyelashes (5 patients).

CONCLUSIONS

Patients with Menkes' syndrome exhibit a high prevalence of several ocular findings, including some (very poor visual acuity, myopia, strabismus) that may warrant special care. Early ocular examination is thus indicated for patients with Menkes' syndrome, particularly those with mild variants of the disease, whose neurologic status is better and lifespan is longer.

Clinical manifestations and treatment of Menkes disease and its variants

The clinical manifestations of classical Menkes disease, mild Menkes disease and occipital horn syndrome are reviewed. Menkes disease is a neurodegenerative disease with X-linked recessive inheritance. Orally administered copper accumulates in the intestine, resulting in the failure of copper absorption. The primary metabolic defect that causes copper accumulation in the intestine is present in almost all extrahepatic tissues. The blood, liver and brain are in a state of copper deficiency, which is due to defective copper absorption. The characteristic features, including neurological disturbances, arterial degeneration and hair abnormalities, can be explained by the decrease in cuproenzyme activities. DNA-based diagnosis is now possible. Mild Menkes disease and occipital horn syndrome, which show milder forms than Menkes disease, have been identified as genetic disorders resulting from mutations in the Menkes disease gene. Because the clinical spectrum of Menkes disease is wide, males with mental retardation and connective tissue abnormalities should be evaluated for biochemical evidence of defective copper transport. The treatment accepted currently is parenteral administration of copper. When treatment is started in patients with classical Menkes disease above the age of 2 months, it does not improve the neurological degeneration. When the treatment is initiated in newborn babies affected with this disease, the neurological degeneration can be prevented in some, but not all, cases. Moreover, early treatment cannot improve non-neurological problems, such as connective tissue laxity. Therefore, alternative therapies for Menkes disease and occipital horn syndrome should be studied.

Metabolic and molecular bases of Menkes disease and occipital horn syndrome

Menkes disease and occipital horn syndrome (OHS) are related disorders of copper transport that involve abnormal neurodevelopment, connective tissue problems, and often premature death. Location of the gene responsible for these conditions on the X chromosome was indicated by pedigree analysis from the time of these syndromes' earliest descriptions. Characterization of an affected female with an X-autosomal translocation was used to identify the Menkes/OHS gene, which encodes a highly evolutionarily conserved, copper-transporting P-type ATPase. The gene normally is expressed in nearly all human tissues, and it localizes to the trans-Golgi network of cells. However, in over 70% of Menkes and OHS patients studied, expression of this gene has been demonstrated to be abnormal. Major gene deletions detectable by Southern blotting account for 15-20% of patients, and an interesting spectrum of other mutations is evident among 58 families whose precise molecular defects have been reported as of this writing. The center region of the gene seems particularly prone to mutation, and those that influence mRNA processing and splicing appear to be relatively common. Further advances in understanding the molecular and cell biological mechanisms involved in normal copper transport may ultimately yield new and better approaches to the management of these disorders.

Spectrum of EEG findings in Menkes disease

We evaluated electroencephalograms (EEGs) in 10 boys with Menkes disease, ranging in age from 9 days to 27 months. Three of 10 tracings were normal (the newborn, his 27-month-old half-brother with the classic phenotype, and a 27-month-old mildly affected patient). Plasma copper levels were low in all patients except the newborn and tended to be lowest in patients whose EEGs were moderately or severely abnormal. EEG differences in Menkes patients could reflect biochemical and molecular heterogeneity with respect to copper availability and utilization in the brain.

Menkes disease: an X-linked neurological disorder of the copper metabolism

Menkes disease is an X-linked, recessive disturbance of copper metabolism associated with a progressive clinical course and abnormal hair. The disease is dominated by neurological symptoms combined with connective tissue manifestations, most of which can be explained by the lack of important copper enzymes. Despite excessive accumulation of the metal in various tissues, a functional copper deficiency is evident, probably caused by a defective intracellular copper transport protein of unknown nature. The molecular basis of the copper disturbance has proven difficult to define and will most likely have to await cloning of the gene. The chromosomal region of interest has now been narrowed down to a sub-band on the long arm of the chromosome (Xq13.3), and positional cloning is in progress in a number of laboratories including our own. Identification of the Menkes gene will be of importance for our understanding of the cellular handling of copper and other trace elements.

[Menkes syndrome: review of the pathogenesis apropos of a clinico-pathological case]

The authors report a case of Menkes' syndrome, probably the first one described in Brazil. The patient, a 15-month-old boy, showed pili torti, early progressive psychomotor deterioration and seizures. Serum levels of ceruloplasmin and copper were very low. Neuroradiological and roentgenological examinations revealed diffuse cerebral atrophy, arterial changes and bone abnormalities. At the post-mortem examination the more consistent findings were cerebral atrophy, neuronal loss in the thalamus and above all cerebellar cortical lesions. The disease has a sex-linked recessive inheritance and is believed to be caused by an inborn error of copper metabolism, perhaps subordinated to changes of proteins which carry copper to different tissues. The relevant literature in relation to the pathogenesis is reviewed.

Menkes's syndrome

Menkes's syndrome (trichopoliodystrophy) is an x-linked, recessive genodermatosis characterized by hair defects, severe retardation, convulsions, progressive neurologic deterioration, and early death. Recent studies in copper metabolism suggest that Menkes's syndrome may be a storage disease in which copper is irreversibly trapped in some tissues by metallothionein, a heavy-metal-binding protein. This then gives rise to a deficiency elsewhere, particularly in the brain, causing irreversible damage in the fetus. We present a patient with Menkes's syndrome and review the clinical and metabolic aspects of this disease.

Menkes' syndrome: an updated review

Menkes' syndrome is an X-linked recessive multisystem disease which is usually fatal prior to 5 years of age. Though originally felt to be a disorder of copper deficiency, it now appears to be a copper storage disease, with the observed defects resulting from inappropriate systemic copper distribution. Disorders in the metabolism of metallothionein, a metalloprotein involved in cellular copper transport, may be the primary defect in this syndrome. This review summarizes the relevant clinical and pathologic findings seen in this condition to date. It also describes some of the abnormalities in the metabolism of copper and metallothionein in these infants.