Early treatment of Menkes disease with parenteral Cooper-Histidine: Long-term follow-up of four treated patients

Deep intronic variant causes aberrant splicing of ATP7A in a family with a variable occipital horn syndrome phenotype

Genetic variants in ATP7A are associated with a spectrum of X-linked disorders. In descending order of severity, these are Menkes disease, occipital horn syndrome, and X-linked distal spinal muscular atrophy. After 30 years of diagnostic investigation, we identified a deep intronic ATP7A variant in four males from a family affected to variable degrees by a predominantly skeletal phenotype, featuring bowing of long bones, elbow joints with restricted mobility which dislocate frequently, coarse curly hair, chronic diarrhoea, and motor coordination difficulties. Analysis of whole genome sequencing data from the Genomics England 100,000 Genomes Project following clinical re-evaluation identified a deep intronic ATP7A variant, which was predicted by SpliceAI to have a modest splicing effect. Using a mini-gene splicing assay, we determined that the intronic variant results in aberrant splicing. Sanger sequencing of patient cDNA revealed ATP7A transcripts with exon 5 skipping, or inclusion of a novel intron 4 pseudoexon. In both instances, frameshift leading to premature termination are predicted. Quantification of ATP7A mRNA transcripts using a qPCR assay indicated that the majority of transcripts (86.1 %) have non-canonical splicing, with 68.0 % featuring exon 5 skipping, and 18.1 % featuring the novel pseudoexon. We suggest that the variability of the phenotypes within the affected males results from the stochastic effects of splicing. This deep intronic variant, resulting in aberrant ATP7A splicing, expands the understanding of intronic variation on the ATP7A-related disease spectrum.

Early clinical signs and treatment of Menkes disease

Menkes disease (MD) is an X-linked recessive disorder caused by mutations in ATP7A. Patients with MD exhibit severe neurological and connective tissue disorders due to copper deficiency and typically die before 3 years of age. Early treatment with copper injections during the neonatal period, before the occurrence of neurological symptoms, can alleviate neurological disturbances to some degree. We investigated whether early symptoms can help in the early diagnosis of MD. Abnormal hair growth, prolonged jaundice, and feeding difficulties were observed during the neonatal period in 20 of 69, 16 of 67, and 3 of 18 patients, respectively. Only three patients visited a physician during the neonatal period; MD diagnosis was not made at that point. The mean age at diagnosis was 8.7 months. Seven patients, who were diagnosed in the prenatal stage or soon after birth, as they had a family history of MD, received early treatment. No diagnosis was made based on early symptoms, highlighting the difficulty in diagnosing MD based on symptoms observed during the neonatal period. Patients who received early treatment lived longer than their elderly relatives with MD. Three patients could walk and did not have seizures. Therefore, effective newborn screening for MD should be prioritized.

ATP7A mutation with occipital horns and distal motor neuropathy: A continuum

ATP7A-related copper transport disorders are classically separated in three pathologies according to their severity, all inherited in an X-linked recessive manner: Menkes disease (MD, OMIM #309400) which represent more than 90% of cases; occipital Horn Syndrome (OHS, OMIM #304150) and ATP7A-related distal motor neuropathy also named X-linked distal spinal muscular atrophy-3 (SMAX3, OMIM #300489) (Kennerson et al., 2010). Although there is no clear cut correlation between Cu and ceruloplasmin levels in ATP7A related disorders, these three entities probably represent a continuum partly depending on residual functional ATP7A protein (Møller, 2015). Thus far OHS and SMAX3 only partially overlap. In fact patients with OHS usually have no distal motor neuropathy signs but, on the other hand, occipital horns, which are the main sign of OHS, have not been described in SMAX3 patient. We describe here a patient bearing a missense ATP7A mutation with associated signs of distal motor neuropathy as well as occipital horns, confirming that OHS and SMAX3 are a continuum.

Histidine: A Systematic Review on Metabolism and Physiological Effects in Human and Different Animal Species

Histidine is an essential amino acid (EAA) in mammals, fish, and poultry. We aim to give an overview of the metabolism and physiological effects of histidine in humans and different animal species through a systematic review following the guidelines of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). In humans, dietary histidine may be associated with factors that improve metabolic syndrome and has an effect on ion absorption. In rats, histidine supplementation increases food intake. It also provides neuroprotection at an early stage and could protect against epileptic seizures. In chickens, histidine is particularly important as a limiting factor for carnosine synthesis, which has strong anti-oxidant effects. In fish, dietary histidine may be one of the most important factors in preventing cataracts. In ruminants, histidine is a limiting factor for milk protein synthesis and could be the first limiting AA for growth. In excess, histidine supplementation can be responsible for eating and memory disorders in humans and can induce growth retardation and metabolic dysfunction in most species. To conclude, the requirements for histidine, like for other EAA, have been derived from growth and AA composition in tissues and also have specific metabolic roles depending on species and dietary levels.

Menkes disease complicated by concurrent Koolen-de Vries syndrome (17q21.31 deletion)

Background

Koolen‐de Vries (KdV) syndrome is caused by a 17q21.31 deletion leading to clinical symptoms of hypotonia and developmental delay and can present with abnormal hair texture. Menkes disease is an X‐linked recessive inherited disease caused by pathogenic variants in ATP7A, which leads to profound copper deficiency.

Method

We identified an infant male who presented with prematurity, hypotonia, and dysmorphic features for whom a family history of clinical Menkes disease was revealed after discussion with the clinical genetics team.

Results

Although initial first‐tier genetic testing identified Kdv syndrome (17q21.31 syndrome), the family history led the team to consider a second diagnostic possibility, and testing of ATP7A revealed a pathogenic variant (c.601C>T, p.R201X).

Conclusion

Menkes disease and KdV syndrome may both present with hypotonia and abnormal hair, in addition to seizures and failure to thrive. While these genetic conditions have overlapping clinical features, they have different natural histories and different therapeutic options. Here, we report on a patient affected with both disorders and review the diagnostic and therapeutic difficulties this presented.

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.

Emergent embolization of a ruptured splenic artery aneurysm complicating Menkes disease

We report a 7-year-old boy with Menkes disease complicated by rupture of a large splenic artery aneurysm. The aneurysm was successfully embolized with microcoils and n-butyl cyanoacrylate. Further angiographic evaluation revealed marked tortuosity of mesenteric and lower extremity vasculature, including the femoral arteries bilaterally, without aneurysm formation. The patient has since been evaluated annually with computed tomography angiography and there have been no additional vascular complications of his disease during 3-year follow up.

Chelating principles in Menkes and Wilson diseases: Choosing the right compounds in the right combinations at the right time

Dysregulation of copper homeostasis in humans is primarily found in two genetic diseases of copper transport, Menkes and Wilson diseases, which show symptoms of copper deficiency or overload, respectively. However, both diseases are copper storage disorders despite completely opposite clinical pictures. Clinically, Menkes disease is characterized by copper deficiency secondary to poor loading of copper-requiring enzymes although sufficient body copper. Copper accumulates in non-hepatic tissues, but is deficient in blood, liver, and brain. In contrast, Wilson disease is characterized by symptoms of copper toxicity secondary to accumulation of copper in several organs most notably brain and liver, and a saturated blood copper pool. It is a challenge to correct copper dyshomeostasis in either disease though copper depletion in Menkes disease is most challenging. Both diseases are caused by defective copper export from distinct cells, and we seek to give new angles and guidelines to improve treatment of these two complementary diseases. Therapy of Menkes disease with copper-histidine, thiocarbamate, nitrilotriacetate or lipoic acid is discussed. In Wilson disease combination of a hydrophilic chelator e.g. trientine or dimercaptosuccinate with a brain shuttle e.g. thiomolybdate or lipoate, is discussed. New chelating principles for copper removal or delivery are outlined.

Cerebrospinal Fluid-Directed rAAV9-rsATP7A Plus Subcutaneous Copper Histidinate Advance Survival and Outcomes in a Menkes Disease Mouse Model

Menkes disease is a lethal neurodegenerative disorder of copper metabolism caused by mutations in an evolutionarily conserved copper transporter, ATP7A. Based on our prior clinical and animal studies, we seek to develop a therapeutic approach suitable for application in affected human subjects, using the mottled-brindled (mo-br) mouse model that closely mimics the Menkes disease biochemical and clinical phenotypes. Here, we evaluate the efficacy of low-, intermediate-, and high-dose recombinant adeno-associated virus serotype 9 (rAAV9)-ATP7A delivered to the cerebrospinal fluid (CSF), in combination with subcutaneous administration of clinical-grade copper histidinate (sc CuHis, IND #34,166). Mutant mice that received high-dose (1.6 × 1010 vg) cerebrospinal fluid-directed rAAV9-rsATP7A plus sc copper histidinate showed 53.3% long-term (≥300-day) survival compared to 0% without treatment or with either treatment alone. The high-dose rAAV9-rsATP7A plus sc copper histidinate-treated mutant mice showed increased brain copper levels, normalized brain neurochemical levels, improvement of brain mitochondrial abnormalities, and normal growth and neurobehavioral outcomes. This synergistic treatment effect represents the most successful rescue to date of the mo-br mouse model. Based on these findings, and the absence of a large animal model, we propose cerebrospinal fluid-directed rAAV9-rsATP7A gene therapy plus subcutaneous copper histidinate as a potential therapeutic approach to cure or ameliorate Menkes disease.

A 37-year-old Menkes disease patient-Residual ATP7A activity and early copper administration as key factors in beneficial treatment

Menkes disease (MD) is a lethal disorder characterized by severe neurological symptoms and connective tissue abnormalities; and results from malfunctioning of cuproenzymes, which cannot receive copper due to a defective intracellular copper transporting protein, ATP7A. Early parenteral copper-histidine supplementation may modify disease progression substantially but beneficial effects of long-term treatment have been recorded in only a few patients. Here we report on the eldest surviving MD patient (37 years) receiving early-onset and long-term copper treatment. He has few neurological symptoms without connective tissue disturbances; and a missense ATP7A variant, p.(Pro852Leu), which results in impaired protein trafficking while the copper transport function is spared. These findings suggest that some cuproenzymes maintain their function when sufficient copper is provided to the cells; and underline the importance of early initiated copper treatment, efficiency of which is likely to be dependent on the mutant ATP7A function.

Characterization of ATP7A missense mutants suggests a correlation between intracellular trafficking and severity of Menkes disease

Menkes disease (MD) is caused by mutations in ATP7A, encoding a copper-transporting P-type ATPase which exhibits copper-dependent trafficking. ATP7A is found in the Trans-Golgi Network (TGN) at low copper concentrations, and in the post-Golgi compartments and the plasma membrane at higher concentrations. Here we have analyzed the effect of 36 ATP7A missense mutations identified in phenotypically different MD patients. Nine mutations identified in patients with severe MD, virtually eliminated ATP7A synthesis, in most cases due to aberrant RNA splicing. A group of 21 predominantly severe mutations led to trapping of the protein in TGN and displayed essentially no activity in a yeast-based functional assay. These were predicted to inhibit the catalytic phosphorylation of the protein. Four mutants showed diffuse post-TGN localization, while two displayed copper dependent trafficking. These six variants were identified in patients with mild MD and typically displayed activity in the yeast assay. The four post-TGN located mutants were presumably affected in the catalytic dephosphorylation of the protein. Together these results indicate that the severity of MD correlate with cellular localization of ATP7A and support previous studies indicating that phosphorylation is crucial for the exit of ATP7A from TGN, while dephosphorylation is crucial for recycling back to TGN.

Copper comes of age in Melbourne

When we were asked to produce articles for this volume, it seemed appropriate to us to co-author an article on the history and impact of copper research in Melbourne. It is appropriate because over many years, decades in fact, we worked closely together and with Professor David Danks to identify the molecular defect in Menkes disease. This work was always carried out with the intention of understanding the nature of the copper homeostatic mechanisms and a "copper pathway" in the cell, that David had the prescience to predict must exist despite scepticism from granting agencies! He indeed inspired us to pursue research careers in this field. This article outlines some of this history.

Novel mutations and clinical outcomes of copper-histidine therapy in Menkes disease patients

Menkes disease is a very rare X-linked copper metabolism disorder that results from an ATP7A gene mutation. With the advent of subcutaneous copper-histidine therapy, the early diagnosis of Menkes disease becomes of utmost importance for patients' prognosis. In the present study, the clinical characteristics of 12 Korean patients with Menkes disease (11 males and 1 female from 11 unrelated families) were described along with the mutation spectrum. Only 2 male patients were diagnosed in the neonatal period, and the other male patients were diagnosed at age 4.3 ± 1.9 months. The presenting signs included depigmented kinky hair, neurologic deficits, and hypotonia. Serum copper and ceruloplasmin levels were markedly decreased. Intracranial vessels were dilated with tortuosity and accompanied by regional cerebral infarctions, even at an early age. Of note, the female patient was diagnosed at age 18 months, during the evaluation for developmental delay, by characteristic MRA findings, biochemical profiles, and genetic evaluation. A total of 11 ATP7A mutations were identified, including five previously unreported mutations. Most mutations were truncated (except 1 missense mutation), including 3 frameshift, 2 nonsense, 3 large deletion, and 2 splice-site variants. The age at commencement of copper-histidine treatment was variable among patients age 7.3 ± 7.5 (0.5-27) months. Despite the treatment, seven patients died before age 5 years, and the remaining patients were severely retarded in neurodevelopment. The poor outcomes of our patients might be related to delayed therapy, but severe ATP7A mutations should be noted as well.

Changes in body weight and height in survivors of Menkes disease

OBJECTIVE

To explore the changes in the body weight and height of Menkes disease (MNK) patients treated with long-term copper-histidine.

METHODS

A survey involving a retrospective review of medical records or summaries of MNK patients was conducted. Patients were 44 males born after 1994, and their feeding method and genetic analysis of the ATP7A gene were reviewed. We compared the data of body weight and height from birth until 6 years between classical MNK patients and the general population obtained from national data and between patients who received early treatment and patients who received late treatment.

RESULTS

Although five patients who received early treatment reached some developmental milestones, the body weight and height did not differ from patients who received late treatment in the mode of oral nutrition, and were lower in comparison to the national data (<3 percentile).

CONCLUSION

We reported changes in the body weight and height of MNK patients who received early and late treatment. Although early treatment with copper-histidine had favorable effects on neurological development, it did not result in improvements in body weight and height. We suggest that the establishment of sufficient nutritional support is necessary along with early parenteral copper treatment to improve whole body condition in MNK patients.

PET imaging analysis with 64Cu in disulfiram treatment for aberrant copper biodistribution in Menkes disease mouse model

Menkes disease (MD), an X-linked recessive disorder of copper metabolism caused by mutations in the copper-transporting ATP7A gene, results in growth failure and severe neurodegeneration in early childhood. Subcutaneous copper-histidine injection is the standard treatment for MD, but it has limited clinical efficacy. Furthermore, long-term copper injection causes excess copper accumulation in the kidneys, resulting in renal dysfunction. To attempt to resolve this issue, we used PET imaging with (64)Cu to investigate the effects of disulfiram on copper biodistribution in living mice serving as an animal model for MD (MD model mice).

METHODS

Macular mice were used as MD model mice, and C3H/He mice were used as wild-type mice. Mice were pretreated with 2 types of chelators (disulfiram, a lipophilic chelator, and d-penicillamine, a hydrophilic chelator) 30 min before (64)CuCl2 injection. After (64)CuCl2 injection, emission scans covering the whole body were performed for 4 h. After the PET scans, the brain and kidneys were analyzed for radioactivity with γ counting and autoradiography.

RESULTS

After copper injection alone, marked accumulation of radioactivity ((64)Cu) in the liver was demonstrated in wild-type mice, whereas in MD model mice, copper was preferentially accumulated in the kidneys (25.56 ± 3.01 percentage injected dose per gram [%ID/g]) and was detected to a lesser extent in the liver (13.83 ± 0.26 %ID/g) and brain (0.96 ± 0.08 %ID/g). Copper injection with disulfiram reduced excess copper accumulation in the kidneys (14.54 ± 2.68 %ID/g) and increased copper transport into the liver (29.42 ± 0.98 %ID/g) and brain (5.12 ± 0.95 %ID/g) of MD model mice. Copper injection with d-penicillamine enhanced urinary copper excretion and reduced copper accumulation in most organs in both mouse groups. Autoradiography demonstrated that disulfiram pretreatment induced copper transport into the brain parenchyma and reduced copper accumulation in the renal medulla.

CONCLUSION

PET studies with (64)Cu revealed that disulfiram had significant effects on the copper biodistribution of MD. Disulfiram increased copper transport into the brain and reduced copper uptake in the kidneys of MD model mice. The application of (64)Cu PET for the treatment of MD and other copper-related disorders may be useful in clinical settings.

Modeling of Menkes disease via human induced pluripotent stem cells

Menkes disease (MD) is a copper-deficient neurodegenerative disorder that manifests severe neurologic symptoms such as seizures, lethargic states, and hypotonia. Menkes disease is due to a dysfunction of ATP7A, but the pathophysiology of neurologic manifestation is poorly understood during embryonic development. To understand the pathophysiology of neurologic symptoms, molecular and cellular phenotypes were investigated in Menkes disease-derived induced pluripotent stem cells (MD-iPSCs). MD-iPSCs were generated from fibroblasts of a Menkes disease patient. Abnormal reticular distribution of ATP7A was observed in MD-fibroblasts and MD-iPSCs, respectively. MD-iPSCs showed abnormal morphology in appearance during embryoid body (EB) formation as compared with wild type (WT)-iPSCs. Intriguingly, aberrant switch of E-cadherin (E-cad) to N-cadherin (N-cad) and impaired neural rosette formation were shown in MD-iPSCs during early differentiation. When extracellular copper was chelated in WT-iPSCs by treatment with bathocuprione sulfate, aberrant switch of E-cad to N-cad and impaired neuronal differentiation were observed, like in MD-iPSCs. Our results suggest that neurological defects in Menkes disease patients may be responsible for aberrant cadherin transition and impaired neuronal differentiation during early developmental stage.

An overview and update of ATP7A mutations leading to Menkes disease and occipital horn syndrome

Menkes disease (MD) is a lethal multisystemic disorder of copper metabolism. Progressive neurodegeneration and connective tissue disturbances, together with the peculiar "kinky" hair, are the main manifestations. MD is inherited as an X-linked recessive trait, and as expected the vast majority of patients are males. MD occurs because of mutations in the ATP7A gene and the vast majority of ATP7A mutations are intragenic mutations or partial gene deletions. ATP7A is an energy-dependent transmembrane protein, which is involved in the delivery of copper to the secreted copper enzymes and in the export of surplus copper from cells. Severely affected MD patients die usually before the third year of life. A cure for the disease does not exist, but very early copper-histidine treatment may correct some of the neurological symptoms. This study reviews 274 published and 18 novel disease causing mutations identified in 370 unrelated MD patients, nonpathogenic variants of ATP7A, functional studies of the ATP7A mutations, and animal models of MD.

L-threo-dihydroxyphenylserine corrects neurochemical abnormalities in a Menkes disease mouse model

OBJECTIVE

Menkes disease is a lethal neurodegenerative disorder of infancy caused by mutations in a copper-transporting adenosine triphosphatase gene, ATP7A. Among its multiple cellular tasks, ATP7A transfers copper to dopamine beta hydroxylase (DBH) within the lumen of the Golgi network or secretory granules, catalyzing the conversion of dopamine to norepinephrine. In a well-established mouse model of Menkes disease, mottled-brindled (mo-br), we tested whether systemic administration of L-threo-dihydroxyphenylserine (L-DOPS), a drug used successfully to treat autosomal recessive norepinephrine deficiency, would improve brain neurochemical abnormalities and neuropathology.

METHODS

At 8, 10, and 12 days of age, wild-type and mo-br mice received intraperitoneal injections of 200μg/g body weight of L-DOPS, or mock solution. Five hours after the final injection, the mice were euthanized, and brains were removed. We measured catecholamine metabolites affected by DBH via high-performance liquid chromatography with electrochemical detection, and assessed brain histopathology.

RESULTS

Compared to mock-treated controls, mo-br mice that received intraperitoneal L-DOPS showed significant increases in brain norepinephrine (p < 0.001) and its deaminated metabolite, dihydroxyphenylglycol (p < 0.05). The ratio of a non-beta-hydroxylated metabolite in the catecholamine biosynthetic pathway, dihydroxyphenylacetic acid, to the beta-hydroxylated metabolite, dihydroxyphenylglycol, improved equivalently to results obtained previously with brain-directed ATP7A gene therapy (p < 0.01). However, L-DOPS treatment did not arrest global brain pathology or improve somatic growth, as gene therapy had.

INTERPRETATION

We conclude that (1) L-DOPS crosses the blood-brain barrier in mo-br mice and corrects brain neurochemical abnormalities, (2) norepinephrine deficiency is not the cause of neurodegeneration in mo-br mice, and (3) L-DOPS treatment may ameliorate noradrenergic hypofunction in Menkes disease.

Catecholamine metabolites affected by the copper-dependent enzyme dopamine-beta-hydroxylase provide sensitive biomarkers for early diagnosis of menkes disease and viral-mediated ATP7A gene therapy

Menkes disease is a lethal X-linked recessive disorder of copper metabolism caused by mutations in ATP7A, a copper-transporting ATPase with diverse and important biological functions. Partial deficiency of dopamine-beta-hydroxylase is a biochemical hallmark of this illness due to the normal role of ATP7A in delivery of copper as an enzymatic cofactor. We exploited this fact to develop a diagnostic test for Menkes disease, which proved highly sensitive and specific. The assay has enabled early identification of affected patients, leading to enhanced survival and improved neurodevelopment after early copper treatment, including some completely normal outcomes. In preclinical efforts to develop improved therapies for patients with non-copper-responsive ATP7A mutations, we used brain-directed adeno-associated viral gene therapy to rescue a murine model of the disease. Statistically significant improvement in brain catechol ratios correlated with enhanced survival, and cerebrospinal fluid catechols represent candidate surrogate markers of treatment effect in a future gene therapy clinical trial.

Copper signaling in the mammalian nervous system: synaptic effects

Copper is an essential metal present at high levels in the CNS. Its role as a cofactor in mitochondrial ATP production and in essential cuproenzymes is well defined. Menkes and Wilson's diseases are severe neurodegenerative conditions that demonstrate the importance of Cu transport into the secretory pathway. In the brain, intracellular levels of Cu, which is almost entirely protein bound, exceed extracellular levels by more than 100-fold. Cu stored in the secretory pathway is released in a Ca(2+)-dependent manner and can transiently reach concentrations over 100 μM at synapses. The ability of low micromolar levels of Cu to bind to and modulate the function of γ-aminobutyric acid type A (GABA(A)) receptors, N-methyl-D-aspartate (NMDA) receptors, and voltage-gated Ca(2+) channels contributes to its effects on synaptic transmission. Cu also binds to amyloid precursor protein and prion protein; both proteins are found at synapses and brain Cu homeostasis is disrupted in mice lacking either protein. Especially intriguing is the ability of Cu to affect AMP-activated protein kinase (AMPK), a monitor of cellular energy status. Despite this, few investigators have examined the direct effects of Cu on synaptic transmission and plasticity. Although the variability of results demonstrates complex influences of Cu that are highly method sensitive, these studies nevertheless strongly support important roles for endogenous Cu and new roles for Cu-binding proteins in synaptic function/plasticity and behavior. Further study of the many roles of Cu in nervous system function will reveal targets for intervention in other diseases in which Cu homeostasis is disrupted.

The mild form of menkes disease: a 34 year progress report on the original case

Classical Menkes disease is a neurodegenerative disorder caused by mutations in the copper-transporting ATPase ATP7A gene which, when untreated, is usually fatal in early childhood. A mild form of Menkes disease was originally reported in 1981 and clinical progress of the patient at 10 years described subsequently. The causative mutation is c.4085C>T in exon 21, causing an alanine to valine substitution in the highly conserved TM7 domain at the C-terminal end of the Menkes protein. Here we report his status at 34 years of age. Intellectual impairment is mild. Ataxia has nearly resolved but motor retardation, dysarthria and an extreme slow speech rate remain. In contrast to patients with the occipital horn syndrome, there have been no connective tissue complications of his mild Menkes disease. He has been under long-term copper therapy for more than 30 years and he continues to enjoy a good quality of life.

Effect of copper and disulfiram combination therapy on the macular mouse, a model of Menkes disease

Menkes disease (MD) is a genetic neurodegenerative disorder characterized by copper deficiency due to a defect in ATP7A. Standard treatment involves parenteral copper-histidine administration. However, the treatment is ineffective if initiated after two months of age, because the administered copper accumulates in the blood-brain barrier and is not transported to neurons. To resolve this issue, we investigated the effects of a combination therapy comprising copper and disulfiram, a lipophilic chelator, in the macular mouse, an animal model of MD. Seven-day-old macular mice treated subcutaneously with 50 μg of CuCl(2) on postnatal day 4 were used. The mice were given a subcutaneous injection of CuCl(2) (10 μg) with oral administration of disulfiram (0.3mg/g body weight) twice a week until eight weeks of age, and then sacrificed. Copper concentrations in the cerebellum, liver, and serum of treated macular mice were significantly higher than those of control macular mice, which received only copper. Mice treated with the combination therapy exhibited higher cytochrome c oxidase activity in the brain. The ratios of noradrenaline and adrenaline to dopamine in the brain were also increased by the treatment, suggesting that dopamine β-hydroxylase activity was improved by the combination therapy. Liver and renal functions were almost normal, although renal copper concentration was higher in treated macular mice than in controls. These results suggest that disulfiram facilitates the passage of copper across the blood-brain barrier and that copper-disulfiram combination therapy may be an effective treatment for MD patients.

Treatable inborn errors of metabolism causing intellectual disability: a systematic literature review

BACKGROUND

Intellectual disability ('developmental delay' at age<5 years) affects 2.5% of population worldwide. Recommendations to investigate genetic causes of intellectual disability are based on frequencies of single conditions and on the yield of diagnostic methods, rather than availability of causal therapy. Inborn errors of metabolism constitute a subgroup of rare genetic conditions for which an increasing number of treatments has become available. To identify all currently treatable inborn errors of metabolism presenting with predominantly intellectual disability, we performed a systematic literature review.

METHODS

We applied Cochrane Collaboration guidelines in formulation of PICO and definitions, and searched in Pubmed (1960-2011) and relevant (online) textbooks to identify 'all inborn errors of metabolism presenting with intellectual disability as major feature'. We assessed levels of evidence of treatments and characterised the effect of treatments on IQ/development and related outcomes.

RESULTS

We identified a total of 81 'treatable inborn errors of metabolism' presenting with intellectual disability as a major feature, including disorders of amino acids (n=12), cholesterol and bile acid (n=2), creatine (n=3), fatty aldehydes (n=1); glucose homeostasis and transport (n=2); hyperhomocysteinemia (n=7); lysosomes (n=12), metals (n=3), mitochondria (n=2), neurotransmission (n=7); organic acids (n=19), peroxisomes (n=1), pyrimidines (n=2), urea cycle (n=7), and vitamins/co-factors (n=8). 62% (n=50) of all disorders are identified by metabolic screening tests in blood (plasma amino acids, homocysteine) and urine (creatine metabolites, glycosaminoglycans, oligosaccharides, organic acids, pyrimidines). For the remaining disorders (n=31) a 'single test per single disease' approach including primary molecular analysis is required. Therapeutic modalities include: sick-day management, diet, co-factor/vitamin supplements, substrate inhibition, stemcell transplant, gene therapy. Therapeutic effects include improvement and/or stabilisation of psychomotor/cognitive development, behaviour/psychiatric disturbances, seizures, neurologic and systemic manifestations. The levels of available evidence for the various treatments range from Level 1b,c (n=5); Level 2a,b,c (n=14); Level 4 (n=45), Level 4-5 (n=27). In clinical practice more than 60% of treatments with evidence level 4-5 is internationally accepted as 'standard of care'.

CONCLUSION

This literature review generated the evidence to prioritise treatability in the diagnostic evaluation of intellectual disability. Our results were translated into digital information tools for the clinician (www.treatable-id.org), which are part of a diagnostic protocol, currently implemented for evaluation of effectiveness in our institution. Treatments for these disorders are relatively accessible, affordable and with acceptable side-effects. Evidence for the majority of the therapies is limited however; international collaborations, patient registries, and novel trial methodologies are key in turning the tide for rare diseases such as these.

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.

Peptidylgycine α-amidating monooxygenase and copper: a gene-nutrient interaction critical to nervous system function

Peptidylgycine alpha-amidating monooxygenase (PAM), a highly conserved copper-dependent enzyme, is essential for the synthesis of all amidated neuropeptides. Biophysical studies revealed that the binding of copper to PAM affects its structure, and cell biological studies demonstrated that the endocytic trafficking of PAM was sensitive to copper. We review data indicating that genetic reduction of PAM expression and mild copper deficiency in mice cause similar alterations in several physiological functions known to be regulated by neuropeptides: thermal regulation, seizure sensitivity, and anxiety-like behavior.

Pathology, clinical features and treatments of congenital copper metabolic disorders--focus on neurologic aspects

Genetic disorders of copper metabolism, including Menkes kinky hair disease (MD), occipital horn syndrome (OHS) and Wilson's disease (WD) are reviewed with a focus on the neurological aspects. MD and OHS are X-linked recessive disorders characterized by a copper deficiency. Typical features of MD, such as neurologic disturbances, connective tissue disorders and hair abnormalities, can be explained by the abnormally low activity of copper-dependent enzymes. The current standard-of-care for treatment of MD is parenteral administration of copper-histidine. When the treatment is initiated in newborn babies, neurologic degeneration can be prevented, but delayed treatment is considerably less effective. Moreover, copper-histidine treatment does not improve connective tissue disorders. Novel treatments targeting neurologic and connective tissue disorders need to be developed. OHS is the mildest form of MD and is characterized by connective tissue abnormalities. Although formal trials have not been conducted for OHS, OHS patients are typically treated in a similar manner to MD. WD is an autosomal recessive disorder characterized by the toxic effects of chronic exposure to high levels of copper. Although the hepatic and nervous systems are typically most severely affected, initial symptoms are variable, making an early diagnosis difficult. Because early treatments are often critical, especially in patients with neurologic disorders, medical education efforts for an early diagnosis should target primary care physicians. Chelating agents and zinc are effective for the treatment of WD, but neurologic symptoms become temporarily worse just after treatment with chelating agents. Neurologic worsening in patients treated with tetrathiomolybdate has been reported to be lower than rates of neurologic worsening when treating with other chelating agents.

Long-term skeletal findings in Menkes disease

Skeletal findings in infants with Menkes disease, the most characteristic of which are metaphyseal spurs, long-bone fractures and wormian bones, have been widely reported. However, the changes in skeletal features over time are not well known. The long-term findings differ completely from those initially observed and consist of undertubulation and metaphyseal flaring, similar to the findings seen in some types of bone dysplasia. The initial and long-term radiological features in an 8-year-old boy with Menkes disease are illustrated.

Effects of copper supplementation on the structure and content of elements in kidneys of mosaic mutant mice

Menkes disease is an effect of ATP7A gene mutation in humans, coding the Cu-ATP-ase which is essential in intestinal copper absorption and its subsequent transfer to circulation. This mutation results in a deficiency of copper in all tissues except the epithelia of intestine and kidney tubules. Subcutaneous injection of copper ions is the main therapy for Menkes patients. Mosaic (Atp7a(mo-ms)) mice closely simulate the situation in Menkes disease. The aim of this study was to evaluate the changes in structure and element content in kidneys of mosaic mice after copper supplementation. Hematoxylin-eosin staining was used to analyze tissue morphology and atomic absorption spectrometry to estimate Cu and Zn content. X-ray microanalysis was performed to measure Na, Mg, P, Cl, and K content in the cells of the proximal and distal tubules. Copper administration lengthened the lifespan of the mutants but led to its high accumulation and results in severe kidney damage. Karyomegalia, necrosis of tubular and Bowman's capsule epithelium, lesions, and atrophy of glomeruli were observed in the treated mutants. Copper treatment afterwards led to sclerosis of glomeruli and tubules enhanced proliferation of epithelial cells and formation of both polycystic and papillary carcinoma patterns in kidney. We suggest that copper excess may impair the activity of Na(+)/K(+) ATP-ase in renal tubules of ms/- males. The content of Mg, P, and Cl in kidneys in mutants was also changed after copper administration.

Menkes disease

Menkes disease (MD) is a lethal multisystemic disorder of copper metabolism. Progressive neurodegeneration and connective tissue disturbances, together with the peculiar 'kinky' hair are the main manifestations. MD is inherited as an X-linked recessive trait, and as expected the vast majority of patients are males. MD occurs due to mutations in the ATP7A gene and the vast majority of ATP7A mutations are intragenic mutations or partial gene deletions. ATP7A is an energy dependent transmembrane protein, which is involved in the delivery of copper to the secreted copper enzymes and in the export of surplus copper from cells. Severely affected MD patients die usually before the third year of life. A cure for the disease does not exist, but very early copper-histidine treatment may correct some of the neurological symptoms.

Histopathology of an iliac aneurysm in a case of Menkes disease

In Menkes disease, arterial tortuosity is frequent, whereas true aneurysms are rare. Here, we report aneurysmal pathology occurring in an infant with Menkes disease. An iliac aneurysm was diagnosed in a 2-month-old boy and attributed to Menkes syndrome on the basis of plasma copper deficiency. Samples of the aneurysmal wall were taken during surgery for histopathological analysis. As in other forms of aneurysm, the arterial wall was characterized by smooth muscle cell (SMC) disappearance, linked to SMC apoptosis and oxidative stress, areas of mucoid degeneration, and extracellular matrix breakdown, including disappearance of elastic fibers and presence of abnormal collagen.

Menkes kinky hair disease: A case report

An eight month old male infant with protein energy malnutrition was admitted in the hospital with the history of repeated attacks of convulsion since four months of age. He was also suffering from frequent attacks of cough and cold since 6 months of age which was marked prior to admission. The infant had fair complexion, sparse fuzzy wooly hair with marked trunkal hypotonia. He had also mental retardation. Serum copper and ceruloplasmin levels were low, MRI showed prominent extraaxial spaces with gliosis, MR angiography revealed tortuosity of cerebral vessels. Microscopic examination of hair revealed pili torti. The patient was diagnosed as Menkes disease and treated symptomatically. For lack of facilities we were not able to do genetic study.

Suppression mechanisms of COX assembly defects in yeast and human: insights into the COX assembly process

Eukaryotic cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial respiratory chain. COX is a multimeric enzyme formed by subunits of dual genetic origin whose assembly is intricate and highly regulated. In addition to the structural subunits, a large number of accessory factors are required to build the holoenzyme. The function of these factors is required in all stages of the assembly process. They are relevant to human health because devastating human disorders have been associated with mutations in nuclear genes encoding conserved COX assembly factors. The study of yeast strains and human cell lines from patients carrying mutations in structural subunits and COX assembly factors has been invaluable to attain the current state of knowledge, even if still fragmentary, of the COX assembly process. After the identification of the genes involved, the isolation and characterization of genetic and metabolic suppressors of COX assembly defects, reviewed here, have become a profitable strategy to gain insight into their functions and the pathways in which they operate. Additionally, they have the potential to provide useful information for devising therapeutic approaches to combat human disorders associated with COX deficiency.

Copper and iron disorders of the brain

Copper and iron are transition elements essential for life. These metals are required to maintain the brain's biochemistry such that deficiency or excess of either copper or iron results in central nervous system disease. This review focuses on the inherited disorders in humans that directly affect copper or iron homeostasis in the brain. Elucidation of the molecular genetic basis of these rare disorders has provided insight into the mechanisms of copper and iron acquisition, trafficking, storage, and excretion in the brain. This knowledge permits a greater understanding of copper and iron roles in neurobiology and neurologic disease and may allow for the development of therapeutic approaches where aberrant metal homeostasis is implicated in disease pathogenesis.

Brachial artery aneurysms in Menkes disease

Generalized vascular tortuosity caused by deficiency of the copper enzyme lysyl oxidase is frequently noted in Menkes disease, but reported examples of peripheral aneurysms are rare. We describe bilateral brachial artery aneurysms in a 10-month-old infant with classical Menkes disease.

Correction of a mouse model of Menkes disease by the human Menkes gene

The brindled mouse is an accurate model of the fatal human X-linked copper deficiency disorder, Menkes disease. Males carrying the mutant allele of the Menkes gene orthologue Atp7a die in the second week of life. To determine whether the genetic defect in the brindled mice could be corrected by expression of the human Menkes gene, male transgenic mice expressing ATP7A from the chicken beta-actin composite promoter (CAG) were mated with female carriers of the brindled mutation (Atp7a(Mo-br)). Mutant males carrying the transgene survived and were fertile but the copper defect was not completely corrected. Unexpectedly males corrected with one transgenic line (T25#5) were mottled and resembled carrier females, this effect appeared to be caused by mosaic expression of the transgene. In contrast, males corrected with another line (T22#2) had agouti coats. Copper concentrations in tissues of the rescued mutants also resembled those of the heterozygous females, with high levels in kidney (84.6+/-4.9 microg/g in corrected males vs. 137.0+/-44.3 microg/g in heterozygotes) and small intestine (15.6+/-2.5 microg/g in corrected males vs. 15.7+/-2.8 microg/g in heterozygotes). The results show that the Menkes defect in mice is corrected by the human Menkes gene and that adequate correction is obtained even when the transgene expression does not match that of the endogenous gene.

Lumbar and iliac artery aneurysms in Menkes' disease: endovascular cover stent treatment of the lumbar artery aneurysm

We report lumbar and iliac artery aneurysms in a 3-month-old boy with Menkes' disease. The iliac artery aneurysm thrombosed spontaneously, documented by follow-up colour Doppler sonography. The lumbar artery aneurysm was successfully treated using a cover stent. There was no filling of the lumbar artery aneurysm and no stenosis of the cover stent during the 9-month follow-up.

Menkes disease: a rare cause of bilateral inguinal hernias

This case of Menkes disease presented with the uncommon association of bilateral inguinal hernias at the age of 4 months. Further investigation demonstrated classical skeletal and neurological changes of this rare neurodegenerative disorder.

Screening for Menkes disease using the urine HVA/VMA ratio

Menkes disease is a disorder of copper transport that results in early death. Early therapy with parenteral copper-histidine has been shown to markedly improve outcomes. However, early diagnosis is difficult because patients are asymptomatic in early infancy. In Menkes disease, impaired activity of dopamine beta-hydroxylase, a copper-dependent enzyme, leads to increased urine ratios of homovanillic acid/vanillylmandelic acid (HVA/VMA). Urine HVA/VMA ratios ranged from 4.1 to 69.7 among 15 patients with Menkes disease, whereas only 0.18% of controls had ratios greater than 4.0. Thus, the urine HVA/VMA ratio is a useful screening method for Menkes disease.