Case report: NAFLD and maple syrup urine disease: Is there an interplay between branched-chain amino acids and fructose consumption?

Background: The worldwide increase in pediatric overweight and obesity, in parallel with the global increase in the consumption of sucrose and fructose, is associated with non-alcoholic fatty liver disease (NAFLD). Elevated branched-chain amino acids (BCAAs) are a metabolic feature related to obesity and an early risk factor for insulin resistance and NAFLD. However, few studies have assessed metabolic risk factors and nutritional status in maple syrup urine disease (MSUD) patients under restricted BCAA and high carbohydrate diets. Methods and results: Herein, we present a pilot report of a 17-year-old boy with classic MSUD with poor diet compliance and high fructose consumption, mainly during early adolescence. At that time, he was overweight and developed features of metabolic syndrome, including persistently elevated liver enzymes and hepatic steatosis. He underwent liver transplantation at the age of 13 years to prevent the risk of progressive cognitive impairment. Two months later, NAFLD relapsed in the graft, despite a better BCAA balance and weight loss. Nevertheless, 6 months after dietary restriction of fructose consumption, NAFLD had sustainably improved. Conclusion: Childhood overweight and fructose overconsumption are wellestablished driving forces in the development of pediatric NAFLD. However, their role in the early onset and progression of NAFLD in the allograft remains to be established. Furthermore, it is not known whether the dysmetabolic state associated with elevated BCAAs may be contributory. Further studies are required with a cohort of MSUD subjects to validate our findings and to ascertain the possible interaction between a BCAA imbalance and dietary intake in the development of NAFLD.

Metabolic liver diseases presenting with neonatal cholestasis: at the crossroad between old and new paradigms.

Metabolic liver diseases (MLD) are an important group of disorders presenting with neonatal cholestasis (NC). The spectrum of liver involvement is wide and the presumptive diagnosis is traditionally based on clinical and laboratory findings. Recently, next-generation sequencing (NGS) panels have emerged as an appealing tool to diagnose neonatal/infantile cholestatic disorders. The aim of this study was to identify clinical phenotypes of liver injury and contribute to find a diagnostic methodology that integrates new molecular diagnostic tools. We retrospectively analyzed the clinical and biochemical features of 16 patients with MLD and NC. Patients were categorized into three groups: A-NC with liver failure (N = 8): tyrosinemia type I (n = 2), classic galactosemia (n = 5), mitochondrial DNA depletion syndrome (n = 1); B-NC evolving with chronic liver disease (N = 5): argininemia (n = 2); mitochondrial cytopathy (n = 1); congenital disorders of glycosylation type Ia (n = 1); Zellweger syndrome (n = 1); and C-transient NC (N = 3): Niemann-Pick type C (n = 2), citrullinemia type II (n = 1).Conclusion: MLD presenting with NC can be categorized into three main clinical phenotypes of liver injury. We highlight transient NC as a clue for MLD that must be pursued. New molecular diagnostic tools can play a key role, but application criteria must be established to make them cost-effective. What is Known: • Metabolic liver diseases are an important group of disorders presenting with neonatal cholestasis. • The diagnostic approach is challenging and traditionally based on clinical and laboratory findings. Next-generation sequencing is a recent and rapidly developing tool in pediatric hepatology. What is New: • We provide a liver-targeted characterization of metabolic liver diseases presenting with neonatal cholestasis, categorizing them into three clinical phenotypes that may narrow the diagnostic possibilities. • A clinical decision-making algorithm is proposed, in which the NGS technology is integrated.

Neonatal cholestasis: an uncommon presentation of hyperargininemia.

Hyperargininemia is a rare inborn error of metabolism due to arginase deficiency, which is inherited in an autossomal recessive manner. Arginase is the final enzyme of the urea cycle and catalyzes the conversion of arginine to urea and ornithine. This condition typically presents in early childhood (between 2 and 4 years of age) with developmental delay associated with progressive spastic paraparesis. Neonatal presentation is very uncommon with a poorly described outcome. Here, we discuss two cases of neonatal cholestasis as initial clinical presentation of hyperargininemia. In case 1, diagnosis was established at 2 months of age upon investigation of the etiology of cholestatic injury pattern and hepatosplenomegaly, and treatment was then initiated at when the patient was 3 months old. Unfortunately, the patient had progressive biliary cirrhosis to end-stage liver disease complicated with portal hypertension for which she underwent successful orthotopic liver transplant at 7 years of age. In case 2, hyperargininemia was identified through newborn screening and treatment was started when patient was 21 days old. Cholestasis was only identified in the patient's further evaluation and it resolved 2 weeks into treatment. The patient is currently 18 months old and her development and neurological examination remain unremarkable. Neonatal cholestasis as first presentation of hyperargininemia is rare, but this disorder should be included in the differential diagnosis of unexplained cholestasis in the neonate. In fact, these two cases suggest that arginase deficiency may be the cause of cholestatic liver disease.