Menkes' disease: long-term treatment with copper and D-penicillamine

Phenotypic and mutational spectrum of 17 Chinese patients with Menkes Disease

BACKGROUND

Menkes Disease (MD) is a fatal X-linked recessive disorder caused by mutations in the ATP7A gene. Severe cases typically die before the age of three. Mild MD and occipital horn syndrome are variants of MD characterized by a less severe phenotype and longer survival.

OBJECTIVE

This case series aims to validate previous findings, expand the clinical phenotype, identify novel ATP7A mutations of MD patients.

METHODS

Observational data with follow-up were collected from 17 genetically diagnosed Chinese MD patients.

RESULTS

All 17 patients exhibited neurological symptoms, including delayed motor milestones (100%) and seizures (58.8%). Unspecific pregnancy or delivery complications occurred in 9 patients (52.9%). The most prevalent connective tissue problems were abnormal hair (76.5%), followed by skeletal and dental abnormalities (52.9%), skin problems (41.2%) and hernia (35.3%). Sensorineural hearing loss (17.6%) was previously unreported. Coronary artery aneurysm and patent foramen ovale (5.9%) were infrequent. One 16-year-old boy carries pathological exon 3-4 deletion, presents novel mild phenotype including short stature and cerebellar ataxia. Out of 13 patients with follow-up (median: 24 months), 7 patients (53.8%) died with median survival of 40 months (range: 21-48 months), 3 patients (23.1%) show severe motor development delay and 2 (15.4%) have refractory epilepsy, only the mild MD patient shows improved cerebellar ataxia. Sixteen ATP7A mutations were identified including 6 small indels (37.5%), 5 nonsense mutations (31.2%), 2 missense mutations (12.5%), 2 exon deletions (12.5%), and 1 splice site mutation (6.25%). Fourteen mutations were novel.

CONCLUSIONS

Our study further broadens the phenotypic and genotypic spectrums of Menkes disease.

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.

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.

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.

Mottled Mice and Non-Mammalian Models of Menkes Disease

Menkes disease is a multi-systemic copper metabolism disorder caused by mutations in the X-linked ATP7A gene and characterized by progressive neurodegeneration and severe connective tissue defects. The ATP7A protein is a copper (Cu)-transporting ATPase expressed in all tissues and plays a critical role in the maintenance of copper homeostasis in cells of the whole body. ATP7A participates in copper absorption in the small intestine and in copper transport to the central nervous system (CNS) across the blood-brain-barrier (BBB) and blood–cerebrospinal fluid barrier (BCSFB). Cu is essential for synaptogenesis and axonal development. In cells, ATP7A participates in the incorporation of copper into Cu-dependent enzymes during the course of its maturation in the secretory pathway. There is a high degree of homology (>80%) between the human ATP7A and murine Atp7a genes. Mice with mutations in the Atp7a gene, called mottled mutants, are well-established and excellent models of Menkes disease. Mottled mutants closely recapitulate the Menkes phenotype and are invaluable for studying Cu-metabolism. They provide useful models for exploring and testing new forms of therapy in Menkes disease. Recently, non-mammalian models of Menkes disease, Drosophila melanogaster and Danio rerio mutants were used in experiments which would be technically difficult to carry out in mammals.

Standard values for the urine HVA/VMA ratio in neonates as a screen for Menkes disease

BACKGROUND

Menkes disease is a lethal disorder associated with copper metabolism. Although early treatment with copper-histidine injections can improve outcomes, early diagnosis is difficult because the clinical features of Menkes disease are subtle or do not manifest in affected neonates. Previous report stated that the low activity of dopamine β-hydroxylase, a copper-dependent enzyme, leads to increases in the urine homovanillic acid/vanillylmandelic acid (HVA/VMA) ratios in patients with Menkes disease, and indicated that a urine HVA/VMA ratio cut-off value of >4 is useful in screening for Menkes disease.

METHODS

We examined the standard values of the urine HVA/VMA ratio in unaffected neonates and assessed its use as a screening parameter for Menkes disease among neonates. In total, 112 neonates, aged between 1 and 6 days, were enrolled in the study and were classified into 2 groups based on their urine HVA/VMA ratios: high (>4) and low (⩽ 4).

RESULTS

Multivariate logistic analysis revealed that mechanical ventilation was an independent risk factor for a high urine HVA/VMA ratio (odds ratio: 21.94; 95% confidence interval: 2.82-247.03; p=0.004). The mean urine HVA/VMA ratio was 2.47 ± 0.67 among 92 neonates who did not receive mechanical ventilation.

CONCLUSION

This study established standard values for the urine HVA/VMA ratio in newborn babies that could be useful in screening for Menkes disease among neonates.

Neurodevelopment and brain growth in classic Menkes disease is influenced by age and symptomatology at initiation of copper treatment

Menkes disease is an X-linked recessive disorder of brain copper metabolism caused by mutations in an essential mammalian copper transport gene, ATP7A. Untreated affected individuals suffer failure to thrive and neurodevelopmental delays that usually commence at 6-8 weeks of age. Death by age three years is typical. While provision of working copies of ATP7A to the brain by viral vectors is a promising strategy under development, the only treatment currently available is subcutaneous copper injections. These can normalize circulating blood levels and may replete brain copper depending on the molecular context, e.g., the severity of ATP7A mutation and potential presence of mosaicism. In this paper, we summarize somatic growth and neurodevelopmental outcomes for 60 subjects enrolled in a recently concluded phase I/II clinical trial of copper histidine for Menkes disease (ClinicalTrials.gov Identifier: NCT00001262). Primary outcomes indicate highly statistically significant improvements in gross motor, fine motor/adaptive, personal-social, and language neurodevelopment in the cohort of subjects who received early treatment prior to onset of symptoms (n=35). Correlating with these findings, quantitative parameters of somatic growth indicated statistically significant greater growth in head circumference for the initially asymptomatic group, whereas weight and height/length at age three years (or at time of death) did not differ significantly. Mortality at age 3 was higher (50%) in subjects older and symptomatic when treatment commenced compared to the asymptomatic group (28.6%). We conclude that early copper histidine for Menkes disease is safe and efficacious, with treatment outcomes influenced by the timing of intervention, and ATP7A mutation.

Clinical outcomes in Menkes disease patients with a copper-responsive ATP7A mutation, G727R

Menkes disease is a fatal neurodegenerative disorder of infancy caused by defects in an X-linked copper transport gene, ATP7A. Evidence from a recent clinical trial indicates that favorable response to early treatment of this disorder with copper injections involves mutations that retain some copper transport capacity. In three unrelated infants, we identified the same mutation, G727R, in the second transmembrane segment of ATP7A that complemented a Saccharomyces cerevisiae copper transport mutant, consistent with partial copper transport activity. Quantitative reverse transcription-polymerase chain reaction studies showed approximately normal levels of ATP7A(G727R) transcript in two patients' fibroblasts compared to wild-type controls, but Western blot analyses showed markedly reduced quantities of ATP7A, suggesting post-translational degradation. We confirmed the latter by comparing degradation rates of mutant and wild-type ATP7A via cyclohexamide treatment of cultured fibroblasts; half-life of the G727R mutant was 2.9h and for the wild-type, 11.4h. We also documented a X-box binding protein 1 splice variant in G727R cells-known to be associated with the cellular misfolded protein response. Patient A, diagnosed 6 months of age, began treatment at 228days (7.6 months) of age. At his current age (2.5 years), his overall neurodevelopment remains at a 2- to 4-month level. In contrast, patient B and patient C were diagnosed in the neonatal period, began treatment within 25 days of age, and show near normal neurodevelopment at their current ages, 3years (patient B), and 7 months (patient C). The poor clinical outcome in patient A with the same missense mutation as patient A and patient B with near normal oucomes, confirms the importance of early medical intervention in Menkes disease and highlights the critical potential benefit of newborn screening for this disorder.

Neonatal diagnosis and treatment of Menkes disease

BACKGROUND

Menkes disease is a fatal neurodegenerative disorder of infancy caused by diverse mutations in a copper-transport gene, ATP7A. Early treatment with copper injections may prevent death and illness, but presymptomatic detection is hindered by the inadequate sensitivity and specificity of diagnostic tests. Exploiting the deficiency of a copper enzyme, dopamine-beta-hydroxylase, we prospectively evaluated the diagnostic usefulness of plasma neurochemical levels, assessed the clinical effect of early detection, and investigated the molecular bases for treatment outcomes.

METHODS

Between May 1997 and July 2005, we measured plasma dopamine, norepinephrine, dihydroxyphenylacetic acid, and dihydroxyphenylglycol in 81 infants at risk. In 12 newborns who met the eligibility criteria and began copper-replacement therapy within 22 days after birth, we tracked survival and neurodevelopment longitudinally for 1.5 to 8 years. We characterized ATP7A mutations using yeast complementation, reverse-transcriptase-polymerase-chain-reaction analysis, and immunohistochemical analysis.

RESULTS

Of 81 infants at risk, 46 had abnormal neurochemical findings indicating low dopamine-beta-hydroxylase activity. On the basis of longitudinal follow-up, patients were classified as affected or unaffected by Menkes disease, and the neurochemical profiles were shown to have high sensitivity and specificity for detecting disease. Among 12 newborns with positive screening tests who were treated early with copper, survival at a median follow-up of 4.6 years was 92%, as compared with 13% at a median follow-up of 1.8 years for a historical control group of 15 late-diagnosis and late-treatment patients. Two of the 12 patients had normal neurodevelopment and brain myelination; 1 of these patients had a mutation that complemented a Saccharomyces cerevisiae copper-transport mutation, indicating partial ATPase activity, and the other had a mutation that allowed some correct ATP7A splicing.

CONCLUSIONS

Neonatal diagnosis of Menkes disease by plasma neurochemical measurements and early treatment with copper may improve clinical outcomes. Affected newborns who have mutations that do not completely abrogate ATP7A function may be especially responsive to early copper treatment. (ClinicalTrials.gov number, NCT00001262.)

Drug targets in Menkes disease - prospective developments

Menkes disease (MNK) is an X-linked recessive disorder characterised by a copper-transporting ATPase defect. In the affected cells, copper transport from the cytosol to the Golgi apparatus is disturbed, resulting in a reduction of copper efflux. Orally-administered copper, which accumulates in the intestine, cannot be absorbed and thus a copper deficiency arises. The characteristic features of MNK are progressive neurological degeneration, connective tissue disorders and hair abnormalities, which are caused by a reduction in the activity of several copper-dependent enzymes, due to concomitant copper deficiency. Subcutaneous injections of copper-histidine complex, which currently forms the accepted mode of treatment, prevent the neurological degeneration in some patients when the treatment is initiated soon after birth. However, when the treatment is started later, the neurological degenerative processes are not prevented. Moreover, the treatment does not improve the connective tissue disorders that are caused by the low activity of lysyl oxidase. In order to solve these problems, a form of the treatment aimed at delivering copper into the Golgi apparatus should be studied. An attempt is made in this review to present what is currently known about MNK and its variants, the efficacy and problems of currently accepted treatments and finally therapeutic targets in MNK.

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.

Menkes disease: recent advances and new aspects

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Menkes disease: recent advances and new insights into copper metabolism

Copper is a trace element necessary for the normal function of several important enzymes but copper homeostasis is still poorly understood. In recent years remarkable progress has been made in this field following the isolation of the gene defective in Menkes disease. Menkes disease and occipital horn syndrome are X-linked recessive disorders, demonstrating the vital importance of copper, which is also highly toxic in excessive amounts. Its destructive effects are reflected in the autosomal recessive Wilson's disease. Progressive neurodegeneration and connective tissue disturbances are the main manifestations of Menkes disease. Although many patients present a severe clinical course, variable forms can be distinguished, and the occipital horn syndrome has been suggested to be a mild allelic form. The Menkes locus is mapped to Xq13.3 and the gene defective in Menkes disease has been isolated by positional cloning. The gene is predicted to encode an energy-dependent copper-binding protein, the first intracellular copper transporter described in eukaryotes. Isolation of the gene and subsequent characterization of the exon-intron organization now enables the establishment of DNA-based diagnostic methods. Furthermore, identification of the Menkes disease gene led to other important findings, such as isolation of its mouse homologue, confirming the allelic relationship between Menkes disease and occipital horn syndrome, and isolation of the defective genes in Wilson's disease and its rat homologue.

Early copper therapy in classic Menkes disease patients with a novel splicing mutation

To correlate genotype with response to early copper histidine therapy in Menkes disease, an X-linked disorder of copper transport, we performed mutational analysis in 2 related males who began treatment at the age of 10 days and prenatally at 32 weeks' gestation, respectively. A G to T transversion at the -1 exonic position of a splice donor site was identified, predicting a glutamine to histidine substitution at codon 724 of the Menkes copper-transporting ATPase gene. The Q724H mutation disrupts proper splicing and generates five mutant transcripts that skip from one to four exons. None of these transcripts is predicted to encode a functional copper transport protein. Copper histidine treatment normalized circulating copper and ceruloplasmin levels but did not improve the baseline deficiency of dopamine-beta-hydroxylase, a copper-dependent enzyme. At the age of 36 months, the first patient was living and had neurodevelopmental abilities ranging from 10 to 15 months. The second patient also showed delayed neurodevelopment and died of pulmonary complications at the age of 5 1/2 months. We conclude that early copper histidine therapy does not normalize neurological outcome in patients with the Q724H splicing mutation, and suggest that preservation of some residual Menkes ATPase activity may be a general prerequisite for significant clinical efficacy from such treatment.

Histochemical localization of copper in various organs of brindled mice after copper therapy

Copper (Cu) distribution in various organs of brindled mice (BM), an animal model of Menkes disease, was studied histochemically and by atomic-absorption-spectrophotometry 7 months after Cu injections. The results were compared with those of untreated BM. In the treated BM brain, a diffuse reduction in Cu-related staining of neurons and astroglia was still evident, though it had improved to some extent. The reduction was noticeable in the thalamus, brain stem and cerebellum, although intensely stained capillaries were noted occasionally in the retrosplenial and mediobasal temporal areas, including the hippocampus. In the treated BM liver, near normalization of Cu distribution was observed. In the treated BM intestine, the main localization of Cu accumulation was in histiocytes/macrophages in the lamina propria, while in the untreated BM it was in the absorptive and secretory epithelial cells. In the treated BM kidney, there was no clear improvement in Cu distribution. These histochemical results were consistent with the data obtained by the spectrophotometric assay. Electron microscopic histochemistry of affected renal tubular epithelial cells revealed numerous silver grains, which represent Cu++ localization, distributed only within the cytoplasm outside organella and nucleus. This suggests impaired intracellular Cu transport from cytosol to organella, which in the kidney is refractory to the Cu therapy adopted.

X;1 translocation in a female Menkes patient: characterization by fluorescence in situ hybridization

Menkes disease is an X-linked recessive disorder of copper metabolism, characterized by progressive neurological degeneration, abnormal hair and connective tissue manifestations. We present a female Menkes patient, with classical Menkes features, carrying a de novo balanced translocation 46,X,t(X;1)(q13;q12). The breakpoint on the X chromosome was narrowed down to Xq13.3 within a 1 Mb YAC contig containing the Menkes gene, using fluorescence in situ hybridization. The translocated X chromosome was of paternal origin and non-randomly active leading to the expression of the disease. This was additional evidence for paternal origin of de novo chromosome rearrangements, including all the X; autosomal translocations examined so far.

Clinical and biochemical consequences of copper-histidine therapy in Menkes disease

Menkes disease (MD) is an X-linked recessively inherited neurodegenerative disorder of copper (Cu) metabolism leading to death in early childhood. Symptoms are attributed to deficient activity of Cu-dependent enzymes. Limited experience has been reported concerning clinical and biochemical consequences of parenteral treatment with copper-(histidine)2-complex (Cu-His) in MD. Cu-His was administered in a 13-week-old boy with MD by daily intramuscular injections. After 6 weeks of therapy, Cu and caeruloplasmin in serum and Cu in CSF were normalized. The excessive dopamine level in CSF was corrected after 3 months of treatment. After 6 weeks of Cu supplementation, complete reduction of epileptic discharges, improved muscular tone and increased motor activities were observed. Developmental regression stopped and was replaced by a slight progression. Death at the age of 19 months was caused by septicaemia due to a fulminant urinary tract infection; there was no evidence of chronic Cu toxicity. These findings suggest that Cu-His supplementation may be a promising palliative treatment in MD.

Sibling cases of a degenerative neurological disease associated with hypocupraemia and hypobetalipoproteinaemia

We describe two siblings, a boy and his younger sister, with degenerative neurological disturbances, hypocupraemia and hypobetalipoproteinaemia. The neurological features in both cases were developmental delay, dysarthria, hyperkinetics with an attention deficit, dysdiadochokinesis, night blindness, myoclonic jerks and convulsions. Their serum cooper levels did not increase despite administration of copper sulphate both orally or intravenously. The copper contents of the cultured fibroblasts in the patients were 1.5-fold that of controls. Although neurological disorders associated with abnormal copper metabolism and inherited in an X-linked manner have been previously reported, this is the first report of a neurodegenerative disease concurrent with abnormal copper metabolism and hypobetalipoproteinaemia.

Recent developments in Menkes disease

Recent studies on Menkes disease are reviewed, focusing especially on copper transport in the cells. A large amount of copper accumulated in the organelle-free cytoplasm, whereas mitochondria were in a state of copper deficiency, indicating that Menkes mutation probably affects copper transport from the cytosol to the organelles in the cells. Microscopic observation of the brain of the macular mouse showed that copper accumulates in the blood vessels. Observation of the brain tissue of the macular mouse after intraventricular administration of copper revealed that copper accumulates in the glia as well as the blood vessels. Copper accumulation was also observed in cultured astrocytes, a type of glial cell, indicating that the affected astrocytes accumulate blood-borne copper and release little of it in the patients with Menkes disease. Thus the effective treatment of Menkes disease could possibly be to release trapped copper from the blood vessels and glia into the neurons.

Changes of copper level and cytochrome c oxidase activity in the macular mouse with age

The macular mouse is an animal model of Menkes disease. The neurological degeneration is caused by decreased cuproenzymes activity, such as cytochrome c oxidase (CCO), associated with copper deficiency in the brain. We investigated the age-related changes in copper concentration and CCO activity in the brain of macular mice which were given a single injection of cupric on postnatal day 7. The copper concentration in the brain of macular mice was always about 40% of that of the age-matched controls. However, the copper concentration of both macular and control mice increased with age gradually. The CCO activity in the brain of macular mice was significantly lower than that of controls at the age of 8 days. However the activity in macular mice increased with growth and reached a level equal to the controls at 180 days. These results suggest that the improvement of CCO activity in the brain of macular mice is due to the brain copper concentration which increased with age. Therefore, parenteral administration of copper is recommended especially during infancy in patients with Menkes disease.

Abnormal movements in brindled mutant mouse heterozygotes: as related to the development of their offspring--biochemical and morphological studies

As a possible preventive measure for brain dysfunction in Menkes disease, prenatal treatment by maternal administration of zinc, vitamin E and copper was examined in brindled mutant mice. During pregnancy and lactation, female heterozygous mice received 20 ppm zinc or 0.004% alpha-tocopherol acetate (vitamin E) throughout and 6 ppm copper from gestational day 13 in the drinking fluid, ad libitum. The maternal administration of zinc and vitamin E, as antioxidants, or copper resulted in decreased fetal and neonatal death of offspring, especially those of hemizygous males, as compared with the administration of water only. When offspring did not grow, maternal abnormal movements, which comprised rotatory movements of high speed with tremor and ataxia, were frequently observed. In the heterozygotes with abnormal movements, the level of lipid peroxidation in cerebrum and the concentration of copper in kidney were much higher than those in the heterozygotes with normal movement. Morphologically, in cerebellum of the heterozygotes with abnormal movements, the loss of Purkinje cells, abundance of lipofuscin granules and abnormal mitochondria or degenerative bodies of high electron density were frequently observed, as compared with heterozygotes with normal movement. These findings suggest that the development of hemizygous male mice may be influenced by both copper and oxygen radical metabolism.