Pre-school neurocognitive and functional outcomes after liver transplant in children with early onset urea cycle disorders, maple syrup urine disease, and propionic acidemia: An inception cohort matched-comparison study

Physical function in children and adolescents pre- and 1-year post-liver transplant

BACKGROUND

Several studies describe poorer motor developmental motor outcomes post-liver transplant (LT) in younger children. Limited studies examine physical function in older children and adolescents pre- and post-LT.

METHODS

Retrospective review of standard of care physical function outcome measures pre- and 1-year post-LT in children ≥6 years at LT. Measures include: 6-minute walk test (6MWT), grip strength, Bruininks-Oseretsky Test of Motor Proficiency-2 (BOT-2) components, Physical Activity Questionnaire (PAQ), and Paediatric Quality of Life Multidimensional Fatigue Scale. Association of medical variables with outcomes was explored.

RESULTS

The study cohort included 23 (8 male, median (interquartile range) age 11.67 (8.25, 13.92) years at LT) participants. Top two primary diagnoses included biliary atresia (30.4%) and fulminant hepatic failure (21.7%). At 1-year post-LT, over one-third (36%) were overweight or obese. Compared with healthy norms, children had significantly lower pre-LT PAQ scores (p = .002), pre- and post-6MWT scores (p < .001) and post-LT BOT-2 strength and agility scores (p < .001). Pre-LT, lower balance scores were associated with abdominal distention/ascites (p = .009) and splenomegaly (p = .017). Lower pre-LT platelet count correlated with poorer balance (r = .532, p = .017) and lower strength and agility scores (r = .446, p = .043). Significant moderate inverse correlations were found between weight/body mass index z-scores and BOT-2 components. Post-LT children continue to demonstrate decreased levels of motor proficiency and functional capacity but report less fatigue and increased physical activity.

CONCLUSIONS

Older children and adolescents undergoing LT are at risk of decreased physical function, highlighting the need for pre- and post-LT rehabilitation to optimize long term outcomes.

Challenges and strategies for clinical trials in propionic and methylmalonic acidemias

Clinical trial development in rare diseases poses significant study design and methodology challenges, such as disease heterogeneity and appropriate patient selection, identification and selection of key endpoints, decisions on study duration, choice of control groups, selection of appropriate statistical analyses, and patient recruitment. Therapeutic development in organic acidemias (OAs) shares many challenges with other inborn errors of metabolism, such as incomplete understanding of natural history, heterogenous disease presentations, requirement for sensitive outcome measures and difficulties recruiting a small sample of participants. Here, we review strategies for the successful development of a clinical trial to evaluate treatment response in propionic and methylmalonic acidemias. Specifically, we discuss crucial decisions that may significantly impact success of the study, including patient selection, identification and selection of endpoints, determination of the study duration, consideration of control groups including natural history controls, and selection of appropriate statistical analyses. The significant challenges associated with designing a clinical trial in rare disease can sometimes be successfully met through strategic engagement with experts in the rare disease, seeking regulatory and biostatistical guidance, and early involvement of patients and families.

Organic acidemias in the neonatal period: 30 years of experience in a referral center for inborn errors of metabolism

OBJECTIVES

Neonatal-onset organic acidemias (OAs) account for 80% of neonatal intensive care unit (NICU) admissions due to inborn errors of metabolism. The aim of this study is to analyze clinical features and follow-up of neonates diagnosed with OAs in a metabolic referral center, focusing on perinatal characteristics and the impact of first the metabolic crisis on long-term outcome.

METHODS

Perinatal features, clinical and laboratory characteristics on admission and follow-up of 108 neonates diagnosed with OAs were retrospectively analyzed. Global developmental delay, abnormal electroencephalogram (EEG) or brain magnetic resonance imaging (MRI), chronic complications, and overall mortality. Associations between clinical findings on admission and outcome measures were evaluated.

RESULTS

Most prevalent OA was maple syrup urine disease (MSUD) (34.3%). Neonates with methylmalonic acidemia (MMA) had significantly lower birth weight (p<0.001). Metabolic acidosis with increased anion gap was more frequent in MMA and propionic acidemia (PA) (p=0.003). 89.1% of OAs were admitted for recurrent metabolic crisis. 46% had chronic non-neurologic complications; 19.3% of MMA had chronic kidney disease. Abnormal findings were present in 26/34 of EEG, 19/29 of MRI studies, and 32/33 of developmental screening tests. Metabolic acidosis on admission was associated with increased incidence of abnormal EEG (p=0.005) and overall mortality (p<0.001). Severe hyperammonemia in MMA was associated with overall mortality (33.3%) (p=0.047). Patients diagnosed between 2007-2017 had lower overall mortality compared to earlier years (p<0.001).

CONCLUSIONS

Metabolic acidosis and hyperammonemia are emerging predictors of poor outcome and mortality. Based on a large number of infants from a single center, survival in neonatal-onset OA has increased over the course of 30 years, but long-term complications and neurodevelopmental results remain similar. While prompt onset of more effective treatment may improve survival, newer treatment modalities are urgently needed for prevention and treatment of chronic complications.

Motor outcomes in young children pre-and one-year post-liver transplant

BACKGROUND

Motor skill acquisition plays an important role in physical activity participation and overall social and physical health. Limited studies have examined motor development in children pre-and post-liver transplant (LT).

METHODS

Retrospective review of motor outcomes in children <6 years old with cholestatic liver disease assessed pre-and 1-year post-isolated LT. Measures include Alberta Infant Motor Scale and Peabody Developmental Motor Scales (gross motor quotient (GMQ), fine motor quotient (FMQ), and total motor quotient (TMQ)). Association of medical variables with motor outcomes was explored.

RESULTS

Participants included 33 (58% male) children with diagnoses of biliary atresia (70%), Alagille syndrome (21%), and others (9%). Median age at LT was 10 (IQR 7.0-20.5) months. Pre-LT >75% of children were at risk for motor delay (≤10^th percentile on AIMS/ ≥1SD below mean GMQ). Post-LT, 52% scored ≥1 SD below the mean GMQ compared with 22% FMQ. Children at risk/delayed pre-LT had an increased risk of motor delay on GMQ post-LT (odds ratio 11.43, 95% CI 1.12-116.7, p = .017). Higher INR pre-LT correlated with lower TMQ post-LT (r = -.51, p = .003). Longer waitlist time correlated with lower FMQ post-LT (r = .41, p = .03). GMQ post-LT and height z-scores pre-LT (r = .46, p = .02) and post-LT (r = .45, p < .01) were positively correlated. There was no correlation with presence of ascites, weight z-score, length of hospitalization, and age at LT.

CONCLUSIONS

Young children have increased risk of motor delay pre-LT, which may persist post-LT. Severity of liver disease and growth delays may impact motor development, highlighting the need for ongoing rehabilitation pre- and post-LT.

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.

Role of liver transplantation in urea cycle disorders: Report from a nationwide study in Japan

Urea cycle disorders (UCDs) are inherited metabolic diseases causing hyperammonemia by defects in urea cycle enzymes or transporters. Liver transplantation (LT) currently is the only curative treatment option until novel therapies become available. We performed a nationwide questionnaire-based study between January 2000 and March 2018 to investigate the effect of LT in patients with UCDs in Japan. A total of 231 patients with UCDs were enrolled in this study. Of them, a total of 78 patients with UCDs (30 male and 16 female ornithine transcarbamylase deficiency (OTCD), 21 carbamoyl phosphate synthetase 1 deficiency (CPSD), 10 argininosuccinate synthetase deficiency (ASSD) and 1 arginase 1 deficiency (ARGD)) had undergone LT. Concerning the maximum blood ammonia levels at the onset time in the transplanted male OTCD (N = 28), female OTCD (N = 15), CPSD (N = 21) and ASSD (N = 10), those were median 634 (IQR: 277-1172), 268 (211-352), 806 (535-1382), and 628 (425-957) μmol/L, respectively. The maximum blood ammonia levels in female OTCD were thus significantly lower than in the other UCDs (all P < .01). LT was effective for long-term survival, prevented recurrent hyperammonemia attack, and lowered baseline blood ammonia levels in patients with UCDs. LT had limited effect for ameliorating neurodevelopmental outcome in patients with severe disease because hyperammonemia at the onset time already had a significant impact on the brain. Patients with ASSD may be more likely to survive without cognitive impairment by receiving early LT despite severe neonatal hyperammonemia ≥ 360 μmol/L. In patients with neonatal onset OTCD or CPSD, there may be additional factors with adverse effects on the brain that are not improved by LT.

Metabolic Control and "Ideal" Outcomes in Liver Transplantation for Maple Syrup Urine Disease

OBJECTIVES

To assess outcomes following liver transplantation for maple syrup urine disease by determining attainment and sustainability of metabolic control and apply an "ideal" outcome composite in long-term survivors.

STUDY DESIGN

A single center, retrospective review collected clinical data including branched-chain amino acid (leucine, isoleucine, and valine) levels following liver transplant and determined achievement of an ideal long-term outcome profile of a first allograft stable on immunosuppression monotherapy, normal growth, and absence of common transplant-related sequelae.

RESULTS

Of 77 patients meeting inclusion criteria identified, 23 were long-term (≥10-year) survivors and were additionally assessed for ideal outcome attainment. Patient and graft survival were 100% and 99%, respectively, and all patients were on an unrestricted protein intake diet. Although significant variation was noted in mean isoleucine (P < .01) and leucine (P < .05) levels postliver transplantation, no difference was seen in valine (P = .29) and overall clinical impact was likely negligible as metabolic stability was achieved and sustained beyond 3 years postliver transplantation and no metabolic crises were identified. Of 23 long-term survivors with available data, 9 (39%) achieved all composite metrics determined to define "ideal" outcomes in pediatric postliver transplantation populations.

CONCLUSIONS

Liver transplant enables long-term metabolic stability for patients with maple syrup urine disease. A combination of experience and improvement in both pre- and postliver transplantation care has enabled excellent survival and minimal comorbidities following transplant.

Pre-school neurocognitive and functional outcomes after liver transplant in children with early onset urea cycle disorders, maple syrup urine disease, and propionic acidemia: An inception cohort matched-comparison study

Background

Urea cycle disorders (UCD) and organic acid disorders classically present in the neonatal period. In those who survive, developmental delay is common with continued risk of regression. Liver transplantation improves the biochemical abnormality and patient survival is good. We report the neurocognitive and functional outcomes post‐transplant for nine UCD, three maple syrup urine disease, and one propionic acidemia patient.

Methods

Thirteen inborn errors of metabolism (IEM) patients were individually one‐to‐two matched to 26 non‐IEM patients. All patients received liver transplant. Wilcoxon rank sum test was used to compare full‐scale intelligence‐quotient (FSIQ) and Adaptive Behavior Assessment System‐II General Adaptive Composite (GAC) at age 4.5 years. Dichotomous outcomes were reported as percentages.

Results

FSIQ and GAC median [IQR] was 75 [54, 82.5] and 62.0 [47.5, 83] in IEM compared with 94.5 [79.8, 103.5] and 88.0 [74.3, 97.5] in matched patients (P‐value <.001), respectively. Of IEM patients, 6 (46%) had intellectual disability (FSIQ and GAC <70), 5 (39%) had autism spectrum disorder, and 1/13 (8%) had cerebral palsy, compared to 1/26 (4%), 0, 0, and 0% of matched patients, respectively. In the subgroup of nine with UCDs, FSIQ (64[54, 79]), and GAC (56[45, 75]) were lower than matched patients (100.5 [98.5, 101] and 95 [86.5, 99.5]), P = .005 and .003, respectively.

Conclusion

This study evaluated FSIQ and GAC at age 4.5 years through a case‐comparison between IEM and matched non‐IEM patients post‐liver transplantation. The neurocognitive and functional outcomes remained poor in IEM patients, particularly in UCD. This information should be included when counselling parents regarding post‐transplant outcome.