Split-graft liver transplantation from an adult donor with an unrecognized UCD to a pediatric and adult recipient

Outcomes After Living Donor Liver Transplantation in Pediatric Patients with Inherited Metabolic Diseases

BACKGROUND There is no consensus about the long-term prognosis of pediatric patients with a variety of rare liver diseases but with inherited metabolic diseases (IMDs). We retrospectively reviewed the developmental outcomes of patients with IMDs undergoing living donor liver transplantation (LDLT). MATERIAL AND METHODS Between May 2001 and December 2020, of 314 pediatric patients who underwent LDLT, 44 (14%) had IMDs. The median age at LDLT was 3.0 years old (range 0-15.0 years). Associations between the post-transplant complications and graft survival rate in patients with IMDs and biliary atresia (BA) were calculated. We evaluated the safety of LDLT from heterozygous carrier donors, the prognosis of patients with IMDs who have metabolic defects expressed in other organs, and developmental outcomes of patients with IMDs. RESULTS The 10-year graft survival rates in patients with IMDs and BA were 87% and 94%, respectively (P=0.041), and the causes of graft failure included pneumocystis pneumonia, acute lung failure, hemophagocytic syndrome, hepatic vein thrombosis, portal vein thrombosis, and sepsis. The rate of post-transplant cytomegalovirus viremia in patients with IMDs was higher than that of patients with BA (P=0.039). Of 39 patients with IMDs, 15 patients (38%) had severe motor and intellectual disabilities in 4 patients, intellectual developmental disorders including epilepsy in 2, and attention-deficit hyperactivity disorder in 2. Of 28 patients with IMDs, 13 (46%) needed special education. CONCLUSIONS The long-term outcomes of LDLT in patients with IMDs are good. However, further long-term social and educational follow-up regarding intellectual developmental disorders is needed.

Hereditary Angioedema Post-liver Transplant

Liver transplantation is the standard of care in managing different types of liver disorders as well as a variety of inborn errors of metabolism. In the latter scenario, the liver-based enzyme abnormality is corrected by transplantation. Although rare, liver transplantation may result in the transmission of an inborn error of metabolism to the recipient. The present report describes the development of acquired hereditary angioedema likely following liver transplantation, with notable improvement with the initiation of C1 esterase inhibitor replacement therapy. This case report describes another example of a hepatic synthesis defect that, although rare, but can be acquired from donor's livers.

Review of Multi-Modal Imaging in Urea Cycle Disorders: The Old, the New, the Borrowed, and the Blue

The urea cycle disorders (UCD) are rare genetic disorder due to a deficiency of one of six enzymes or two transport proteins that act to remove waste nitrogen in form of ammonia from the body. In this review, we focus on neuroimaging studies in OTCD and Arginase deficiency, two of the UCD we have extensively studied. Ornithine transcarbamylase deficiency (OTCD) is the most common of these, and X-linked. Hyperammonemia (HA) in OTCD is due to deficient protein handling. Cognitive impairments and neurobehavioral disorders have emerged as the major sequelae in Arginase deficiency and OTCD, especially in relation to executive function and working memory, impacting pre-frontal cortex (PFC). Clinical management focuses on neuroprotection from HA, as well as neurotoxicity from other known and yet unclassified metabolites. Prevention and mitigation of neurological injury is a major challenge and research focus. Given the impact of HA on neurocognitive function of UCD, neuroimaging modalities, especially multi-modality imaging platforms, can bring a wealth of information to understand the neurocognitive function and biomarkers. Such information can further improve clinical decision making, and result in better therapeutic interventions. In vivo investigations of the affected brain using multimodal neuroimaging combined with clinical and behavioral phenotyping hold promise. MR Spectroscopy has already proven as a tool to study biochemical aberrations such as elevated glutamine surrounding HA as well as to diagnose partial UCD. Functional Near Infrared Spectroscopy (fNIRS), which assesses local changes in cerebral hemodynamic levels of cortical regions, is emerging as a non-invasive technique and will serve as a surrogate to fMRI with better portability. Here we review two decades of our research using non-invasive imaging and how it has contributed to an understanding of the cognitive effects of this group of genetic conditions.

Challenges in diagnosing and managing adult patients with urea cycle disorders

Urea cycle disorders (UCD) are a group of rare inherited metabolic conditions of amino acid catabolism caused by an enzyme deficiency within the hepatic ammonia detoxification pathway. The presentation of these disorders ranges from life-threatening intoxication in the neonate to asymptomatic status in adults. Late-onset UCDs can present for the first time in adulthood and may mimic other causes of acute confusion or psychiatric diseases, and are often associated with neurological symptoms. Late-onset UCDs may become apparent during periods of metabolic stress such as rapid weight loss, gastric bypass surgery, chronic starvation or the postpartum period. Early diagnosis is critical for effective treatment and to prevent long-term complications of hyperammonemia. The challenges of management of adults include for example: (a) poor compliance to dietary and medical treatment which can result in recurrent hospital admissions; (b) severe neurological dysfunction; (c) the management of pregnancy and the postpartum period; and (d) access to multidisciplinary care peri-operatively. In this review, we highlight a number of challenges in the diagnosis and management of adult patient with late-onset UCDs and suggest a systematic management approach.

Hyperammonemia and lactic acidosis in adults: Differential diagnoses with a focus on inborn errors of metabolism

The adult endocrinologist may be asked to consult on a patient for unexplained biochemical disturbances that could be caused by an underlying inborn error of metabolism. A genetic disorder is generally less likely to be the cause as these disorders are individually rare, however inborn errors of metabolism are collectively not infrequent and important to consider as they may be treatable and tragic outcomes avoided. Hyperammonemia or lactic acidosis are most often secondary markers of an acquired primary disease process, but they may be a clue to the presence of a genetic disorder. Herein is presented an approach to the differential diagnosis of elevated ammonia and lactate, and a brief discussion of management for when an inborn error is diagnosed.