Unexpected combination of inherited chorea-acanthocytosis with MDR3 (ABCB4) defect mimicking Wilson's disease

Wilson's disease: Revisiting an old friend

Wilson's disease (WD) is a rare condition caused by copper accumulation primarily in the liver and secondly in other organs, such as the central nervous system. It is a hereditary autosomal recessive disease caused by a deficiency in the ATP7B transporter. This protein facilitates the incorporation of copper into ceruloplasmin. More than 800 mutations associated with WD have been described. The onset of the disease frequently includes manifestations related to the liver (as chronic liver disease or acute liver failure) and neurological symptoms, although it can sometimes be asymptomatic. Despite it being more frequent in young people, WD has been described in all life stages. Due to its fatal prognosis, WD should be suspected in all patients with unexplained biochemical liver abnormalities or neurological or psychiatric symptoms. The diagnosis is established with a combination of clinical signs and tests, including the measurement of ceruloplasmin, urinary copper excretion, copper quantification in liver biopsy, or genetic assessment. The pharmacological therapies include chelating drugs, such as D-penicillamine or trientine, and zinc salts, which are able to change the natural history of the disease, increasing the survival of these patients. In some cases of end-stage liver disease or acute liver failure, liver transplantation must be an option to increase survival. In this narrative review, we offer an overview of WD, focusing on the importance of clinical suspicion, the correct diagnosis, and treatment.

ABCB4 variants in adult patients with cholestatic disease are frequent and underdiagnosed

BACKGROUND

Heterozygous ABCB4 variants are not routinely tested in adults with cholestasis because of their supposed rarity and high costs.

METHODS

Nineteen adult patients presenting with unexplained cholestasis, and/or recurrent gallstones were included; genotyping was not done in five due to lack of health insurance approval.

RESULTS

heterozygous ABCB4 variants were identified in seven patients, followed by cascade testing of 12 family members: one patient underwent liver transplantation at age 40 for end-stage liver disease; one had compensated cirrhosis; all symptomatic adults had gallstones, including four with low phospholipid-associated cholelithiasis; four had intrahepatic cholestasis of pregnancy; all children and one 54-year old female were asymptomatic. Genotype: Families A and C: c.2211G>A (p.Ala737=) combined with c.959C>T (p.Ser320Phe) in one subject; Family B: c.1130T>C (p.Ile377Thr); Family D: large deletion removing ABCB4 exons 1-4 plus ABCB1, RUNDC3B, SLC25A40, DBF4, ADAM22 exons 1-3; Family E: c.1565T>C (p.Phe522Ser) ; Family F: c.1356+2T>C combined with c.217C>G (p.Leu73Val). All patients responded to ursodeoxycholic acid.

CONCLUSIONS

We found ABCB4 variants in half of the adults with unexplained cholestasis and/or recurrent gallstones presenting at our center, suggesting that this condition is underdiagnosed and undertreated, with serious consequences not only for the patients and their families, but also in terms of healthcare costs.

Optimized Trientine-dihydrochloride Therapy in Pediatric Patients With Wilson Disease: Is Weight-based Dosing Justified?

OBJECTIVES

The aim of the study was to investigate the efficacy and safety of trientine-dihydrochloride (TD) in pediatric patients with Wilson disease (WD) and the effect of different weight-based dosages on their clinical and biochemical outcome.

METHODS

We retrospectively reviewed the clinical data of 31 children with WD receiving TD therapy ages under 18 years at the time of diagnosis. Outcome measures included parameters of copper metabolism and liver function tests. To examine the impact of different weight-based dosages, 2 dosage subgroups were analyzed. Group 1 received less than 20 mg/kg TD per day, group 2 more than 20 mg · kg-1 · day-1.

RESULTS

Median follow-up was 60 (5-60) months in the total study group. During TD therapy, nonceruloplasmin-bound copper was reduced from mean 1.53 (0.01-6.95) at baseline to 0.62 (0.01-4.57) μmol/l. 24h-urinary copper excretion diminished to 1.85 (0.8-9.6) μmol/day approximating the therapeutic goal of 1.6 μmol/day. Seven of 31 patients (22.6%) required discontinuation of TD treatment, in 4 cases it was because of adverse events (ulcerative colitis, gingival and breast hypertrophy, hirsutism, elevation of transaminases).Investigations about weight-based dosage showed no significant difference of any laboratory parameter between the 2 cohorts. But in terms of clinical safety, adverse effects because of TD were only found in 6.7% of children in group 1 (<20 mg · kg-1 · day-1, median follow-up 60 [9-60] months), whereas in group 2 (>20 mg · kg-1 · day-1, median follow-up 60 [14-60] months), it was 63.6%.

CONCLUSIONS

TD proves to be an efficacious alternative chelating agent for children with WD. Weight-based dosages above the recommended 20 mg · kg-1 · day-1 may increase the rate of adverse effects in pediatric patients.

Update on the Diagnosis and Management of Wilson Disease

PURPOSE OF REVIEW

Exciting developments relating to Wilson disease (WD) have taken place with respect to both basic biological and clinical research. This review critically examines some of these findings and considers their implications for current thinking about WD. It is not a comprehensive review of WD as a clinical disorder.

RECENT FINDINGS

The structure of the gene product of ATP7B, abnormal in WD, is being worked out in detail, along with a broader description of how the protein ATP7B (Wilson ATPase) functions in cells including enterocytes, not only in relation to copper disposition but also to lipid synthesis. Recent population studies raise the possibility that WD displays incomplete penetrance. Innovative screening techniques may increase ascertainment. New strategies for diagnosing and treating WD are being developed. Several disorders have been identified which might qualify as WD-mimics. WD can be difficult to diagnose and treat. Insights from its pathobiology are providing new options for managing WD.

Targeted exome analysis identifies the genetic basis of disease in over 50% of patients with a wide range of ataxia-related phenotypes

PURPOSE

To examine the impact of a targeted exome approach for the molecular diagnosis of patients nationwide with a wide range of ataxia-related phenotypes.

METHODS

One hundred and seventy patients with ataxia of unknown etiology referred from clinics throughout the United States and Canada were studied using a targeted exome approach. Patients ranged in age from 2 to 88 years. Analysis was focused on 441 curated genes associated with ataxia and ataxia-like conditions.

RESULTS

Pathogenic and suspected diagnostic variants were identified in 88 of the 170 patients, providing a positive molecular diagnostic rate of 52%. Forty-six different genes were implicated, with the six most commonly mutated genes being SPG7, SYNE1, ADCK3, CACNA1A, ATP1A3, and SPTBN2, which accounted for >40% of the positive cases. In many cases a diagnosis was provided for conditions that were not suspected and resulted in the broadening of the clinical spectrum of several conditions.

CONCLUSION

Exome sequencing with targeted analysis provides a high-yield approach for the genetic diagnosis of ataxia-related conditions. This is the largest targeted exome study performed to date in patients with ataxia and ataxia-like conditions and represents patients with a wide range of ataxia phenotypes typically encountered in neurology and genetics clinics.

Phenotypic spectrum and diagnostic pitfalls of ABCB4 deficiency depending on age of onset

Genetic variants in the adenosine triphosphate-binding cassette subfamily B member 4 (ABCB4) gene, which encodes hepatocanalicular phosphatidylcholine floppase, can lead to different phenotypes, such as progressive familial intrahepatic cholestasis (PFIC) type 3, low phospholipid-associated cholelithiasis, and intrahepatic cholestasis of pregnancy. The aim of this multicenter project was to collect information on onset and progression of this entity in different age groups and to assess the relevance of this disease for the differential diagnosis of chronic liver disease. Clinical and laboratory data of 38 patients (17 males, 21 females, from 29 families) with homozygous or (compound) heterozygous ABCB4 mutations were retrospectively collected. For further analysis, patients were grouped according to the age at clinical diagnosis of ABCB4-associated liver disease into younger age (<18 years) or adult age (≥18 years). All 26 patients diagnosed in childhood presented with pruritus (median age 1 year). Hepatomegaly and splenomegaly were present in 85% and 96% of these patients, respectively, followed by jaundice (62%) and portal hypertension (69%). Initial symptoms preceded diagnosis by 1 year, and 13 patients received a liver transplant (median age 6.9 years). Of note, 9 patients were misdiagnosed as biliary atresia, Alagille syndrome, or PFIC type 1. In the 12 patients with diagnosis in adulthood, the clinical phenotype was generally less severe, including intrahepatic cholestasis of pregnancy, low phospholipid-associated cholelithiasis, or (non)cirrhotic PFIC3. Conclusion: ABCB4 deficiency with onset in younger patients caused a more severe PFIC type 3 phenotype with the need for liver transplantation in half the children. Patients with milder phenotypes are often not diagnosed before adulthood. One third of the children with PFIC type 3 were initially misdiagnosed, indicating the need for better diagnostic tools and medical education. (Hepatology Communications 2018;2:504-514).

[Liver biopsy in children and adolescents : Preliminary morphological examinations in diffuse liver disease]

BACKGROUND

Frequencies of types of liver disease differ between adults and nonadults (NA).

OBJECTIVES

The particular problems encountered in interpreting liver-biopsy findings in NA often require referral in consultation.  To permit this efficiently, we recommend specific approaches to light microscopy, with special stains and immunohistochemistry, as well as to ultrastructural study.

METHODS

Prosection and the choice of special stains are described, and are discussed in relation to clinical questions.

RESULTS

Histochemical stains (chromatic aniline blue [CAB], Prussian blue [Berlin blue, BBL], periodic acid-Schiff reaction [PAS], diastase-PAS [D‑PAS], reticulin, rhodanine, Victoria blue) and immunohistochemical studies to demonstrate the expression of keratin 7 (cholangiocytes) and macrosialin (CD68; macrophages) as well as electron microscopy are important techniques in the histopathologic  analysis of ontogenetic, storage, and metabolic disorders, hepatitis, hepatosplenomegaly, cholestasis, and portal hypertension.

CONCLUSIONS

Particular histochemical and immunohistochemical studies, as well as electron microscopy, are useful in optimising histopathologic diagnosis and in differential diagnosis.  We believe that these techniques should be part of routine work-up of NA liver-biopsy specimens.

Liver biopsy in children: position paper of the ESPGHAN Hepatology Committee

Liver biopsy (LB) is still the criterion standard procedure for obtaining liver tissue for histopathological examination and a valuable tool in the diagnosis, prognosis, and management of many parenchymal liver diseases. The aim of this position paper is to summarise the present practice of paediatric LB and make recommendations about its performance. Although histological evaluation of the liver is important in assessing prognosis and exploring treatment, noninvasive techniques (ie, imaging, laboratory markers) may replace use of liver histology. The indications for LB are changing as present knowledge of aetiologies, pathomechanism, and therapeutic options in paediatric liver disease is evolving. Adult and paediatric literature was reviewed to assess the existing clinical practice of LB with focus on the technique, indications, risk of complications, and contraindications in paediatrics. This position paper presents types of LB, indications, complications, contraindications, and an essential checklist for paediatric LB.

Mitochondrial dysfunction in a novel form of autosomal recessive ataxia

Defects in the recognition and/or repair of damage to DNA are responsible for a sub-group of autosomal recessive ataxias. Included in this group is a novel form of ataxia with oculomotor apraxia characterised by sensitivity to DNA damaging agents, a defect in p53 stabilisation, oxidative stress and resistance to apoptosis. We provide evidence here that the defect in this patient's cells is at the level of the mitochondrion. Mitochondrial membrane potential was markedly reduced in cells from the patient and ROS levels were elevated. This was accompanied by lipid peroxidation of mitochondrial proteins involved in electron transport and RNA synthesis. However, no gross changes or alteration in composition or activity of mitochondrial electron transport complexes was evident. Sequencing of mitochondrial DNA revealed a mutation, I349T, in the mitochondrial cytochrome b gene. These results describe a patient with an apparently novel form of AOA characterised by a defect at the level of the mitochondrion.

ABCB4 Disease Presenting with Cirrhosis and Copper Overload-Potential Confusion with Wilson Disease

A 2-year-old female with cirrhosis was found to have a liver copper of 248 μg/g dry weight. She was eventually diagnosed with ABCB4 disease on the basis of heterozygote A546D and R176W mutations. Her liver disease was partially responsive to ursodeoxycholic acid therapy. Copper overload occurs in cholestatic liver disease and this must be considered to avoid misdiagnosis of Wilson disease.