Aceruloplasminemia in an asymptomatic patient with a new mutation. Diagnosis and family genetic analysis

The divergent effects of astrocyte ceruloplasmin on learning and memory function in young and old mice

Ceruloplasmin (CP) plays an important role in maintaining iron homeostasis. Cp gene knockout (Cp^-/-) mice develop a neurodegenerative disease with aging and show iron accumulation in the brain. However, iron deficiency has also been observed in 3 M Cp^-/- mice. The use of systemic Cp gene knockout is insufficient to reveal specific functions for CP in the central nervous system. Considering recent discoveries that astrocytes synthetize the majority of brain CP, we generated astrocyte conditional Cp knockout (Cp^GfapcKO) mice, and found that iron contents decreased in the cerebral cortex and hippocampus of young (6 M) and old (18 M) Cp^GfapcKO mice. Further experiments revealed that 6 M Cp^GfapcKO mice exhibited impaired learning and memory function, while 18 M Cp^GfapcKO mice exhibited improved learning and memory function. Our study demonstrates that astrocytic Cp deletion blocks brain iron influx through the blood-brain-barrier, with concomitantly increased iron levels in brain microvascular endothelial cells, resulting in brain iron deficiency and down-regulation of ferritin levels in neurons, astrocytes, microglia and oligodendrocytes. At the young age, the synapse density, synapse-related protein levels, 5-hydroxytryptamine and norepinephrine, hippocampal neurogenesis and myelin formation were all decreased in Cp^GfapcKO mice. These changes affected learning and memory impairment in young Cp^GfapcKO mice. In old Cp^GfapcKO mice, iron accumulation with aging was attenuated, and was accompanied by the alleviation of the ROS-MAPK-apoptosis pathway, Tau phosphorylation and β-amyloid aggregation, thus delaying age-related memory decline. Overall, our results demonstrate that astrocytic Cp deletion has divergent effects on learning and memory function via different regulatory mechanisms induced by decreased iron contents in the brain of mice, which may present strategies for the prevention and treatment of dementia.

Is There a Connection between the Metabolism of Copper, Sulfur, and Molybdenum in Alzheimer’s Disease? New Insights on Disease Etiology

Alzheimer’s disease (AD) and other forms of dementia was ranked 3rd in both the Americas and Europe in 2019 in a World Health Organization (WHO) publication listing the leading causes of death and disability worldwide. Copper (Cu) imbalance has been reported in AD and increasing evidence suggests metal imbalance, including molybdenum (Mo), as a potential link with AD occurrence.We conducted an extensive literature review of the last 60 years of research on AD and its relationship with Cu, sulfur (S), and Mo at out of range levels.Weanalyzed the interactions among metallic elements’ metabolisms;Cu and Mo are biological antagonists, Mo is a sulfite oxidase and xanthine oxidase co-factor, and their low activities impair S metabolism and reduce uric acid, respectively. We found significant evidence in the literature of a new potential mechanism linking Cu imbalance to Mo and S abnormalities in AD etiology: under certain circumstances, the accumulation of Cu not bound to ceruloplasmin might affect the transport of Mo outside the blood vessels, causing a mild Mo deficiency that might lowerthe activity of Mo and S enzymes essential for neuronal activity. The current review provides an updated discussion of the plausible mechanisms combining Cu, S, and Mo alterations in AD.

Emerging Disease-Modifying Therapies in Neurodegeneration With Brain Iron Accumulation (NBIA) Disorders

Neurodegeneration with Brain Iron Accumulation (NBIA) is a heterogeneous group of progressive neurodegenerative diseases characterized by iron deposition in the globus pallidus and the substantia nigra. As of today, 15 distinct monogenetic disease entities have been identified. The four most common forms are pantothenate kinase-associated neurodegeneration (PKAN), phospholipase A2 group VI (PLA2G6)-associated neurodegeneration (PLAN), beta-propeller protein-associated neurodegeneration (BPAN) and mitochondrial membrane protein-associated neurodegeneration (MPAN). Neurodegeneration with Brain Iron Accumulation disorders present with a wide spectrum of clinical symptoms such as movement disorder signs (dystonia, parkinsonism, chorea), pyramidal involvement (e.g., spasticity), speech disorders, cognitive decline, psychomotor retardation, and ocular abnormalities. Treatment remains largely symptomatic but new drugs are in the pipeline. In this review, we discuss the rationale of new compounds, summarize results from clinical trials, provide an overview of important results in cell lines and animal models and discuss the future development of disease-modifying therapies for NBIA disorders. A general mechanistic approach for treatment of NBIA disorders is with iron chelators which bind and remove iron. Few studies investigated the effect of deferiprone in PKAN, including a recent placebo-controlled double-blind multicenter trial, demonstrating radiological improvement with reduction of iron load in the basal ganglia and a trend to slowing of disease progression. Disease-modifying strategies address the specific metabolic pathways of the affected enzyme. Such tailor-made approaches include provision of an alternative substrate (e.g., fosmetpantotenate or 4′-phosphopantetheine for PKAN) in order to bypass the defective enzyme. A recent randomized controlled trial of fosmetpantotenate, however, did not show any significant benefit of the drug as compared to placebo, leading to early termination of the trials' extension phase. 4′-phosphopantetheine showed promising results in animal models and a clinical study in patients is currently underway. Another approach is the activation of other enzyme isoforms using small molecules (e.g., PZ-2891 in PKAN). There are also compounds which counteract downstream cellular effects. For example, deuterated polyunsaturated fatty acids (D-PUFA) may reduce mitochondrial lipid peroxidation in PLAN. In infantile neuroaxonal dystrophy (a subtype of PLAN), desipramine may be repurposed as it blocks ceramide accumulation. Gene replacement therapy is still in a preclinical stage.

Effects of iron chelation therapy on the clinical course of aceruloplasminemia: an analysis of aggregated case reports

Background

Aceruloplasminemia is a rare genetic iron overload disorder, characterized by progressive neurological manifestations. The effects of iron chelation on neurological outcomes have only been described in case studies, and are inconsistent. Aggregated case reports were analyzed to help delineate the disease-modifying potential of treatment.

Methods

Data on clinical manifestations, treatment and neurological outcomes of treatment were collected from three neurologically symptomatic Dutch patients, who received deferiprone with phlebotomy as a new therapeutic approach, and combined with other published cases. Neurological outcomes of treatment were compared between patients starting treatment when neurologically symptomatic and patients without neurological manifestations.

Results

Therapeutic approaches for aceruloplasminemia have been described in 48 patients worldwide, including our three patients. Initiation of treatment in a presymptomatic stage of the disease delayed the estimated onset of neurological manifestations by 10 years (median age 61 years, SE 5.0 vs. median age 51 years, SE 0.6, p = 0.001). Although in 11/20 neurologically symptomatic patients neurological manifestations remained stable or improved during treatment, these patients were treated significantly shorter than patients who deteriorated neurologically (median 6 months vs. median 43 months, p = 0.016). Combined iron chelation therapy with deferiprone and phlebotomy for up to 34 months could be safely performed in our patients without symptomatic anemia (2/3), but did not prevent further neurological deterioration.

Conclusions

Early initiation of iron chelation therapy seems to postpone the onset of neurological manifestations in aceruloplasminemia. Publication bias and significant differences in duration of treatment should be considered when interpreting reported treatment outcomes in neurologically symptomatic patients. Based on theoretical grounds and the observed long-term safety and tolerability in our study, we recommend iron chelation therapy with deferiprone in combination with phlebotomy for aceruloplasminemia patients without symptomatic anemia.

New insights in the neurological phenotype of aceruloplasminemia in Caucasian patients

INTRODUCTION

The diagnosis aceruloplasminemia is usually made in patients with advanced neurological manifestations of the disease. In these patients prognosis is poor, disabilities are severe and patients often die young. The aim of our study was to facilitate recognition of aceruloplasminemia at a disease stage at which treatment can positively influence outcome. Currently, the neurological phenotype of aceruloplasminemia has been mainly described in Japanese patients. This 'classical' phenotype consists of cerebellar ataxia, hyperkinetic movement disorders and cognitive decline. In this study we describe the spectrum of neurological disease in Caucasian patients.

METHODS

Data on neurological presentation and follow-up were gathered from both our patients, homozygous for the G631R mutation in the CP gene, and other published Caucasian cases. Neurological features of aceruloplasminemia in Caucasian patients were compared to those summarized in Japanese patients.

RESULTS

21 Caucasian patients, both ours and the described cases, displayed a wide range of movement disorders with predominant chorea, parkinsonism and ataxia, and also tremor and dystonia. In addition to cognitive decline, nearly half of the Caucasian patients presented with psychiatric changes, including depression, anxiety and behavioral changes. In one-third of the neurologically symptomatic Caucasian patients, cognitive- or psychiatric changes were the first neurological manifestations of aceruloplasminemia.

CONCLUSIONS

Aceruloplasminemia in Caucasian patients can present with a wider range and a different order of neurological symptoms than previously described in Japanese patients. Psychiatric changes and parkinsonism can be added to the spectrum of neurological disease. Cognitive- or psychiatric changes may be the first neurological manifestations of aceruloplasminemia.

Aceruloplasminemia presents as Type 1 diabetes in non-obese adults: a detailed case series

AIM

To detect features that might lead to the early diagnosis and treatment of aceruloplasminemia, as initiation of treatment before the onset of neurological symptoms is likely to prevent neurological deterioration.

METHODS

The PubMed and OMIM databases were searched for published cases of aceruloplasminemia. Diagnostic criteria for aceruloplasminemia were undetectable or very low serum ceruloplasmin, hyperferritinemia and low transferrin saturation. Clinical, biochemical and radiological data on the presentation and follow-up of the cases were extracted and completed through e-mail contact with all authors.

RESULTS

We present an overview of 55 aceruloplasminemia cases, including three previously unreported cases. Diabetes mellitus was the first symptom related to aceruloplasminemia in 68.5% of the patients, manifesting at a median age of 38.5 years, and often accompanied by microcytic or normocytic anaemia. The combination preceded neurological symptoms in almost 90% of the neurologically symptomatic patients and was found 12.5 years before the onset of neurological symptoms.

CONCLUSIONS

There is a diagnostic window during which diabetes and anaemia are present although there is an absence of neurological symptoms. Screening for aceruloplasminemia in adult non-obese individuals presenting with antibody-negative, insulin-dependent diabetes mellitus and unexplained anaemia is recommended. The combination of ferritin and transferrin saturation provides a sensitive initial measure for aceruloplasminemia.

How I Diagnose Non-thalassemic Microcytic Anemias

Microcytic anemia is the most common form of anemia, characterized by reduced hemoglobin (Hb) synthesis associated with decreased red blood cell volume (MCV). It is a very heterogeneous group of diseases that may be either acquired or inherited. Microcytic hypochromic anemia can result from defects in globin (hemoglobinopathies or thalassemias) or heme synthesis or in iron availability, or acquisition by the erythroid precursors. Diagnosis of microcytic anaemia appears to be important in children/adolescents, especially to set, where possible, a treatment plan on the basis of the etiology and pathogenesis. After excluding the acquired causes of microcytic anemia that represent the most frequent etiology, according to the differential diagnosis, the analysis of genetic causes, mostly hereditary, must be considered. This review will consider acquired and hereditary microcytic anemias due to heme synthesis or to iron metabolism defects and their diagnosis.

Aceruloplasminemia: an update

Aceruloplasminemia is an inherited neurodegenerative disorder involving "neurodegeneration with brain iron accumulation," which is caused by genetic defects in the ceruloplasmin gene. Ceruloplasmin is a multicopper oxidase with ferroxidase activity that oxidizes ferrous iron following its transfer to extracellular transferrin. In the central nervous system, a glycosylphosphatidylinositol-linked ceruloplasmin bound to the cell membranes was found to be the major isoform of this protein. Aceruloplasminemia is characterized by diabetes, retinal degeneration, and progressive neurological symptoms, including extrapyramidal symptoms, ataxia, and dementia. Clinical and pathological studies and investigations of cell culture and murine models revealed that there is an iron-mediated cellular radical injury caused by a marked accumulation of iron in the affected parenchymal tissues. The aim of this chapter is to provide an overview of not only the clinical features, genetic and molecular pathogenesis, and treatment of aceruloplasminemia but also the biological and physiological features of iron metabolism.

Dominant mutants of ceruloplasmin impair the copper loading machinery in aceruloplasminemia

The multicopper oxidase ceruloplasmin plays a key role in iron homeostasis, and its ferroxidase activity is required to stabilize cell surface ferroportin, the only known mammalian iron exporter. Missense mutations causing the rare autosomal neurodegenerative disease aceruloplasminemia were investigated by testing their ability to prevent ferroportin degradation in rat glioma C6 cells silenced for endogenous ceruloplasmin. Most of the mutants did not complement (i.e. did not stabilize ferroportin) because of the irreversible loss of copper binding ability. Mutant R701W, which was found in a heterozygous very young patient with severe neurological problems, was unable to complement per se but did so in the presence of copper-glutathione or when the yeast copper ATPase Ccc2p was co-expressed, indicating that the protein was structurally able to bind copper but that metal loading involving the mammalian copper ATPase ATP7B was impaired. Notably, R701W exerted a dominant negative effect on wild type, and it induced the subcellular relocalization of ATP7B. Our results constitute the first evidence of "functional silencing" of ATP7B as a novel molecular defect in aceruloplasminemia. The possibility to reverse the deleterious effects of some aceruloplasminemia mutations may disclose new possible therapeutic strategies.

Aceruloplasminemia: a novel mutation in a family with marked phenotypic variability

Hereditary aceruloplasminemia (HA) is a rare inherited disease characterized by anemia, iron overload, diabetes, and neurodegeneration. HA is caused by the homozygous mutation of the ceruloplasmin (CP) gene. We report two siblings with markedly different phenotypes carrying a novel mutation: a homozygous deletion of two nucleotides (1257-1258 TT del) causing the premature stop of the Cp protein translation (Y401X). An early diagnosis of iron overload was made in the female sibling who was subsequently treated with deferoxamine. At the age of 54, her neurologic symptoms were limited to mild akinetic signs and a history of seizures; moreover, her fasting blood glucose level never exceeded 120 mg/dL. The male sibling, who had not received any specific treatment for HA, developed severe diabetes at the age of 32 and at 48 manifested a progressively disabling neurologic disease. Possible physiopathological bases of these intrafamilial phenotypic variations are discussed.

T2* and FSE MRI distinguishes four subtypes of neurodegeneration with brain iron accumulation

BACKGROUND

Neurodegeneration with brain iron accumulation (NBIA) defines a group of genetic disorders characterized by brain iron deposition and associated with neuronal death. The known causes of NBIA include pantothenate kinase-associated neurodegeneration (PKAN), neuroferritinopathy, infantile neuroaxonal dystrophy (INAD), and aceruloplasminemia.

OBJECTIVE

To define the radiologic features of each NBIA subtype.

METHODS

Brain MRIs from patients with molecularly confirmed PKAN (26 cases), neuroferritinopathy (21 cases), INAD (four cases), and aceruloplasminemia (10 cases) were analyzed blindly to delineate patterns of iron deposition and neurodegeneration.

RESULTS

In most cases of PKAN, abnormalities were restricted to globus pallidus and substantia nigra, with 100% having an eye of the tiger sign. In a minority of PKAN cases there was hypointensity of the dentate nuclei (1/5 on T2* sequences, 2/26 on fast spin echo [FSE]). In INAD, globus pallidus and substantia nigra were involved on T2* and FSE scans, with dentate involvement only seen on T2*. By contrast, neuroferritinopathy had consistent involvement of the dentate nuclei, globus pallidus, and putamen, with confluent areas of hyperintensity due to probable cavitation, involving the pallida and putamen in 52%, and a subset having lesions in caudate nuclei and thalami. More uniform involvement of all basal ganglia and the thalami was typical in aceruloplasminemia, but without cavitation.

CONCLUSIONS

In the majority of cases, different subtypes of neurodegeneration associated with brain iron accumulation can be reliably distinguished with T2* and T2 fast spin echo brain MRI, leading to accurate clinical and subsequent molecular diagnosis.

Cys-881 is essential for the trafficking and secretion of truncated mutant ceruloplasmin in aceruloplasminemia

BACKGROUND/AIMS

Aceruloplasminemia is an inherited iron overload disorder caused by a mutation in the ceruloplasmin gene and characterized by iron accumulation in both the liver and brain. The aim of this study was to elucidate the molecular pathogenesis of aceruloplasminemia by a functional analysis of mutant ceruloplasmin.

METHODS

The effects of nonsense mutations including Y694ter, W858ter and R882ter were studied by the expression in cultured cells.

RESULTS

A biogenesis study demonstrated that the Y694ter and W858ter mutants showed protein synthesis identical to that of wild type protein, however, the mutants were retained in the endoplasmic reticulum (ER), while R882ter mutant was secreted out. Site-directed mutagenesis analyses suggested that Cys-881 was necessary for the secretion of the truncated ceruloplasmin. The W858ter mutant decreased viability in the transfected cells. The expression and the promoter activity of glucose-regulated protein 78 that is an ER stress sensor protein, were up-regulated in the transfected cells.

CONCLUSIONS

The truncated mutant containing Cys-881 was able to pass through the ER and was secreted, while the truncated mutant protein without Cys-881 appeared to accumulate in the ER thus leading to ER stress and eventually resulting in cell death.

Identification and in silico characterization of a novel compound heterozygosity associated with hereditary aceruloplasminemia

BACKGROUND

Hereditary aceruloplasminemia is an adult-onset autosomal recessive disease characterized by increased iron overload in the liver, pancreas, retina, and central nervous system. So far, 45 families with cases of aceruloplasminemia have been reported world-wide and mainly missense and nonsense mutations in the ceruloplasmin gene were detected.

MATERIAL AND METHODS

Here, we report the identification, clinical characterization, and in silico analysis of a novel compound heterozygosity in the ceruloplasmin gene of a 31-year-old man with iron overload.

RESULTS

Increased serum ferritin levels, elevated iron saturation, as well as results of iron quantification in the liver and magnetic resonance imaging-based measurement of T2 relaxation times of the substantia nigra consistently suggested iron overload. By sequencing the ceruloplasmin gene, so far unknown nucleotide replacements G229C, and C2131A were detected in exons 2 and 12, respectively. In silico analyses showed that the resulting amino acid changes Asp58His and Gln692Lys are located at highly conserved positions. The Asp58His mutation is located on the surface of the protein, alters polarity, and may interfere with copper incorporation or ceruloplasmin trafficking. The Gln692Lys mutation is mapped to a beta-strand of domain 4 and may lead to conformational change of the cupredoxin fold.

CONCLUSIONS

As causative for aceruloplasminemia, a formerly unknown compound heterozygosity in the ceruloplasmin gene was identified. In silico characterization suggests an impact on ceruloplasmin conformation and function.

Hepatobiliary pathology

PURPOSE OF REVIEW

Publications concerning liver histopathology in fatty liver disease and chronic hepatitis C, iron and copper overload, and liver transplantation from the past year have been surveyed to highlight useful concepts and diagnostic information.

RECENT FINDINGS

Two microscopic forms of pediatric nonalcoholic steatohepatitis have been described: type 1 in which hepatocyte ballooning and/or pericellular fibrosis accompany the steatosis; and type 2 which has portal tract inflammation and/or fibrosis as the salient accompanying feature. In chronic hepatitis C, the ductular reaction appears to be a major factor associated with fibrosis. In patients transplanted for hepatitis C virus-related cirrhosis, immunostaining of post-transplant liver biopsies for alpha-smooth muscle actin (i.e. in activated hepatic stellate cells) may identify those individuals at risk for severe recurrence. Clinicopathological papers on several forms of non-HFE hemochromatosis were published and Wilson's disease was described in individuals of 60 years or more in age. Cholestasis in childhood was expertly reviewed and histopathologic precursor lesions of hepatocellular carcinoma were also examined in a comprehensive article.

SUMMARY

Recent publications with impact on liver biopsy interpretation include a morphologic classification of nonalcoholic steatohepatitis in childhood, the differential diagnosis of childhood cholestasis and pathogenetic factors involved in fibrogenesis in chronic hepatitis C.

Novel mutation in the ceruloplasmin gene causing a cognitive and movement disorder with diabetes mellitus

In a Chinese woman who had diabetes mellitus, undetectable ceruloplasmin, hand tremor, neck dystonia, and cognitive disturbances, genetic analyses revealed a novel homozygous mutation (848G > C or W283S) in exon 5 in the ceruloplasmin gene. Another member with a milder phenotype was also affected by this mutation. The healthy sister was heterozygous at the same position. Aceruloplasminemia has not yet been reported in China. This case suggests that increased awareness should be paid to this disorder in the presence of the typical symptoms.