Wilson disease (WD) is an autosomal recessive disorder caused by mutations in the ATP7B gene, encoding a copper-transporting adenosine triphosphatase responsible for the ion excess handling and biliary excretion. Copper accumulation and toxicity cause liver disease and multiorgan injury, typically presenting after 3 years of age (1).
We describe a girl with neonatal cholestasis progressed to cirrhosis and end-stage liver disease. Child-parents urgent whole exome sequencing (WES) revealed ATP7B biallelic mutations in the child and her mother, supporting the concomitant diagnosis of WD in consecutive generations. We provide clinical, biochemical, and proteomic data supporting the pathogenic role of ATP7B impairment in this patient, possibly in addition with the prenatal copper overload.
A Bosnian female infant born to nonconsanguineous parents presented with jaundice in ABO incompatibility, and developed cholestasis with hepatosplenomegaly. Family and pregnancy history were unremarkable. She had normal gamma-glutamyltranspeptidase, high serum bile acids, aspartate aminotransferase > alanine aminotransferase. A liver biopsy at 2 months of age showed diffuse giant cell transformation, canalicular cholestasis, moderate lobular activity, minimal steatosis, extramedullary hematopoiesis (Fig. 1A). She was started on ursodeoxycholic acid 20 mg/kg/d.
She worsened, and was evaluated for LT at 7 months with total/conjugated bilirubin of 22/20 mg/dL, prothrombin time international normalized ratio 1.9, aspartate aminotransferase/alanine aminotransferase ×4/×1.5 upper limit of normal, normal gamma-glutamyltranspeptidase, ascites and prerenal kidney injury. She was admitted to pediatric intensive care with multiorgan failure, severe neurological impairment (hypertone, tremor, poor spontaneous motility), and mild left ventricular myocardial hypertrophy. Laryngotracheomalacia, Coombs-negative hemolytic anemia, and central hypothyroidism were also present. After surgical closure of patent ductus arteriosus, she was listed for LT (pediatric end-stage liver disease score = 34). An extensive work-up ruled out infectious and metabolic etiologies (Table 1). An urgent child-parents WES revealed that the girl was compound heterozygote for 2 known WD causing mutations in the ATP7B gene (c.19-20del, causing p.Gln7fs, and c.3207C>A, causing p.His1069Gln); the mother was homozygote for p.His1069Gln, and then was confirmed having WD with cirrhosis, while the father carried p.Gln7fs (Fig. 1B). Patient’s copper metabolism revealed normal serum ceruloplasmin (39 mg/dL, NV > 20), increased basal cupruria (100 μg/24 h, NV < 40), and free cupremia (Fig. 1E). The brain magnetic resonance showed unspecific brain injury: focal (left occipital and periventricular) T2 hyperintensity suggesting gliosis, along with mild supratentorial white matter atrophy, while basal ganglia were normal. She was started on penicillamine 20 mg/kg/d and transplanted soon thereafter. Liver copper on hepatectomy was 350 μg/g dry weight (>5 × upper limit of normal). Histology showed cirrhosis and biliary plugs (Fig. 1C). Hepatocyte ultrastructure showed increased number of mitochondria (Fig. 1D).
TABLE 1. -
Biochemical investigation protocol performed in the patient
||Cortisol, ACTH, TSH, and thyroxine
||Serology (IgG and IgM): HAV, HBV, HCV, HEV, Epstein-Barr Virus (EBV, EBNA IgG, and EBV-VCA IgM), CMV, HSV-1/2, Toxoplasma gondii, rubella, parvovirus B19
|Nucleic acids: EBV-DNA, CMV-DNA, HSV-1/2-DNA, human herpes virus 6
||Serum alpha-1 antitrypsin, plasma and urine amino acids, urine organic acids, serum total bile acids + mass spectrometry urine analysis, transferrin isoelectric focusing, acylcarnitine profile, pyruvic acid, lactic acid, erythrocyte galactose-1-phosphate uridyl transferase activity, urine galactose, urine fructose, chloride sweat test, beta-glucosydase, lysosomal acid lipase, and acid sphingomyelinase on dried blood spot mass spectrometry
ACTH = adrenocorticotropic hormone; CMV = cytomegalovirus; EBNA = Epstein-Barr nuclear antigen; EBV = Epstein-Barr Virus; HAV = hepatitis A; HBV = hepatitis B; HCV = hepatitis C; HEV = hepatitis E; HSV-1/2 = herpes simplex virus-1 and-2; TSH, thyroid-stimulating hormone; VCA = viral capsid antigen.
She is alive and well 4 years after LT with complete neurologic recovery. The mother is well under penicillamine. A 7-year-old brother was diagnosed with asymptomatic WD by screening and started on zinc acetate.
The liver differential transcription pattern (fold change from a healthy liver) of the patient showed higher similarity to WD than that of 3 biliary atresia (BA) control patients: WD-related up- or downregulated genes were 28/61 versus 18/61 in the patient and in BA controls, respectively (Fig. 2A, B).
In both patient and BA livers, an upregulation of gene clusters related to the extracellular matrix organization was present, due to fibrosis (Fig. 2C, D). However, the patient had higher similarity with WD as for an upregulation of the gene subsets related to cell proliferation and response to stimuli, and downregulation of those related to sterol, fatty acid, and cholesterol metabolism and xenobiotic metabolic processes (Fig. 2C–F). Methods for genetic testing (WES), pathology studies, and RNA studies are described in the Supplemental Digital Content, https://links.lww.com/PG9/A58.
Reduced fertility and spontaneous miscarriages are common in WD-untreated mothers, and anecdotal descriptions of copper accumulation in the placenta and in live birth fetuses also exist (3).
This is the first report of a severe infantile liver disease possibly due to WD causing ATP7B mutations. Intrauterine copper exposure due to maternal undiagnosed WD might have contributed to this exceptional phenotype.
WD typically present after infancy, possibly as the result of the ATP7B-independent embryo-fetal and neonatal copper metabolism. At birth, the ion is mostly accumulated intracellularly bound with metallothioneins, while its mobilization toward mitochondria, binding to ceruloplasmin, and ATP7B-driven biliary excretion occur later in infancy (4).
Prenatally accumulated copper may have caused toxicity in the ATP7B-deficient liver when ion handling became ATP7B-dependent.
In support of this hypothesis, the patient showed clinical extrahepatic aspects of WD, met the Leipzig diagnostic criteria including a 7-fold increase in liver tissue copper content, and showed gene expression profile consistent with that of available animal models of WD.
The biochemical markers of copper metabolism should be interpreted with caution in an infant. Liver copper content can be higher than the normal in non-WD cholestatic liver diseases and in healthy newborn and infants (5). Also, the normal serum ceruloplasmin concentration of the present case could be explained by the acute-phase response typical of neonatal/infantile hepatitis. Nevertheless, WD patients carrying at least one missense mutation (like the proband and her brother) are described to have higher and even normal levels of ceruloplasmin (6). The initial histological changes—predominated by hepatocyte giant cell transformation—reflect the most frequent and stereotyped pattern of liver injury in infants. On the other hand, the ultrastructural picture of an expanded mitochondrial compartment could fit the hypothesis of the copper toxicity but also be related to anoxia due to delay in fixation, which is common in hepatectomy specimens. Age-dependent copper accumulation in the mother might explain the fact that—7 years earlier—a pregnancy with the same ATP7B fetal genotype did not present with the same phenotype. However, also genes other than ATP7B as well as epigenetic factors are known to play a role as phenotype modifiers (7).
Given the limits of a single case description, the causative role of ATP7B mutations in determining severe infantile cholestatic liver disease needs to be confirmed in similar cases.
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