Necrotizing enterocolitis and respiratory distress syndrome as first clinical presentation of mitochondrial trifunctional protein deficiency

A case report of necrotizing enterocolitis in a moderately preterm neonate with LCHADD-A call to focus on the basics while utilizing advanced new therapies

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is an autosomal recessive condition of impaired beta-oxidation. Traditionally, treatment included restriction of dietary long-chain fatty acids via a low-fat diet and supplementation of medium chain triglycerides. In 2020, triheptanoin received FDA approval as an alternative source of medium chain fatty acids for individuals with long-chain fatty acid oxidation disorders (LC-FAOD). We present a case of a moderately preterm neonate born at 33 2/7 weeks gestational age with LCHADD who received triheptanoin and developed necrotizing enterocolitis (NEC). Prematurity is known as a major risk factor for NEC, with risk increasing with decreasing gestational age. To our knowledge, NEC has not previously been reported in patients with LCHADD or with triheptanoin use. While metabolic formula is part of the standard of care for LC-FAOD in early life, preterm neonates may benefit from more aggressive attempts to use skimmed human milk to minimize exposure to formula during the risk period for NEC during feed advancement. This risk period may be longer in neonates with LC-FAOD compared to otherwise healthy premature neonates.

Genetic, biochemical, and clinical spectrum of patients with mitochondrial trifunctional protein deficiency identified after the introduction of newborn screening in the Netherlands

Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is included in many newborn screening (NBS) programs. Acylcarnitine-based NBS for LCHADD not only identifies LCHADD, but also the other deficiencies of the mitochondrial trifunctional protein (MTP), a multi-enzyme complex involved in long-chain fatty acid β-oxidation. Besides LCHAD, MTP harbors two additional enzyme activities: long-chain enoyl-CoA hydratase (LCEH) and long-chain ketoacyl-CoA thiolase (LCKAT). Deficiency of one or more MTP activities causes generalized MTP deficiency (MTPD), LCHADD, LCEH deficiency (not yet reported), or LCKAT deficiency (LCKATD). To gain insight in the outcomes of MTP-deficient patients diagnosed after the introduction of NBS for LCHADD in the Netherlands, a retrospective evaluation of genetic, biochemical, and clinical characteristics of MTP-deficient patients, identified since 2007, was carried out. Thirteen patients were identified: seven with LCHADD, five with MTPD, and one with LCKATD. All LCHADD patients (one missed by NBS, clinical diagnosis) and one MTPD patient (clinical diagnosis) were alive. Four MTPD patients and one LCKATD patient developed cardiomyopathy and died within 1 month and 13 months of life, respectively. Surviving patients did not develop symptomatic hypoglycemia, but experienced reversible cardiomyopathy and rhabdomyolysis. Five LCHADD patients developed subclinical neuropathy and/or retinopathy. In conclusion, patient outcomes were highly variable, stressing the need for accurate classification of and discrimination between the MTP deficiencies to improve insight in the yield of NBS for LCHADD. NBS allowed the prevention of symptomatic hypoglycemia, but current treatment options failed to treat cardiomyopathy and prevent long-term complications. Moreover, milder patients, who might benefit from NBS, were missed due to normal acylcarnitine profiles.

Fulminant Necrotizing Enterocolitis and Multiple Organ Dysfunction in a Toddler with Mitochondrial DNA Depletion Syndrome-13

Necrotizing enterocolitis (NEC) is exceptional after the neonatal period. A toddler with encephalopathy, mitochondrial myopathy, and hypertrophic cardiomyopathy developed fatal NEC and multiple organ dysfunction within 48 hours of the introduction of enteral feeding. She was subsequently found to have pathogenic mutations in FBXL4 , a cause of mitochondrial DNA depletion syndrome-13. Intestinal dysmotility in the context of deficient mitochondrial respiration may have contributed to the development of NEC. Current paradigms call for early introduction of enteral nutrition to reinstate energy homeostasis. Enteral feeding should be administered with caution during metabolic crises of patients with mitochondrial DNA depletion syndromes.

Disorders of mitochondrial long-chain fatty acid oxidation and the carnitine shuttle

Mitochondrial fatty acid oxidation is an essential pathway for energy production, especially during prolonged fasting and sub-maximal exercise. Long-chain fatty acids are the most abundant fatty acids in the human diet and in body stores, and more than 15 enzymes are involved in long-chain fatty acid oxidation. Pathogenic mutations in genes encoding these enzymes result in a long-chain fatty acid oxidation disorder in which the energy homeostasis is compromised and long-chain acylcarnitines accumulate. Symptoms arise or exacerbate during catabolic situations, such as fasting, illness and (endurance) exercise. The clinical spectrum is very heterogeneous, ranging from hypoketotic hypoglycemia, liver dysfunction, rhabdomyolysis, cardiomyopathy and early demise. With the introduction of several of the long-chain fatty acid oxidation disorders (lcFAOD) in newborn screening panels, also asymptomatic individuals with a lcFAOD are identified. However, despite early diagnosis and dietary therapy, a significant number of patients still develop symptoms emphasizing the need for individualized treatment strategies. This review aims to function as a comprehensive reference for clinical and laboratory findings for clinicians who are confronted with pediatric and adult patients with a possible diagnosis of a lcFAOD.

Neonatal Screening for Inherited Metabolic Diseases in 2016

The scope of newborn screening (NBS) programs is continuously expanding. NBS programs are secondary prevention interventions widely recognized internationally in the "field of Public Health." These interventions are aimed at early detection of asymptomatic children affected by certain diseases, with the objective to establish a definitive diagnosis and apply the proper treatment to prevent further complications and sequelae and ensure a better quality of life. The most significant event in the history of neonatal screening was the discovery of phenylketonuria in 1934. This disease has been the paradigm of inherited metabolic diseases. The next paradigm was the introduction of tandem mass spectrometry in the NBS programs that make possible the simultaneous measurement of several metabolites and consequently, the detection of several diseases in one blood spot and in an unique analysis. We aim to review the current situation of neonatal screening in 2016 worldwide and show scientific evidence of the benefits for some diseases. We will also discuss future challenges. It should be taken into account that any consideration to expand an NBS panel should involve a rigorous process of decision-making that balances benefits against the risks of harm.

Red blood cell transfusions increase fecal calprotectin levels in premature infants

OBJECTIVE

We hypothesized that red blood cell (RBC) transfusions influence intestinal inflammation in very low birth weight (VLBW) infants. We also suspected that hematocrit (Hct) at transfusions and RBC storage time correlate with intestinal inflammation.

STUDY DESIGN

VLBW infants, without major congenital defects, intestinal perforation or necrotizing enterocolitis, were enrolled prospectively. Fecal calprotectin (FC) levels were measured from stool samples collected before and after RBC transfusions. Data on Hct and RBC storage time were collected.

RESULT

Data from 42 RBC transfusions given to 26 infants revealed that FC levels increased faster than baseline after RBC transfusions (P=0.018) and were higher in multiple-transfused infants (0 to 48 and >48 h post transfusion, P=0.007 and P=0.005, respectively). Lower Hct and RBC storage >21 days correlated with higher FC levels (P=0.044 and P=0.013, respectively).

CONCLUSION

RBC transfusions, anemia and prolonged RBC storage were associated with an increase in intestinal inflammation.

Muscle MRI in patients with long-chain fatty acid oxidation disorders

INTRODUCTION

Muscle magnetic resonance imaging (MRI) is a useful tool for visualizing abnormalities in neuromuscular disorders. The value of muscle MRI has not been studied in long-chain fatty acid oxidation (lcFAO) disorders. LcFAO disorders may present with metabolic myopathy including episodic rhabdomyolysis.

OBJECTIVE

To investigate whether lcFAO disorders are associated with muscle MRI abnormalities.

METHODS

Lower body MRI was performed in 20 patients with lcFAO disorders, i.e. three carnitine palmitoyltransferase 2 deficiency (CPT2D), 12 very long-chain acyl-CoA dehydrogenase deficiency (VLCADD), three mitochondrial trifunctional protein deficiency (MTPD) and two isolated long-chain hydroxyacyl-CoA dehydrogenase deficiency (LCHADD).

RESULTS

At the time of MRI, four patients had muscle weakness, 14 had muscle pain and 13 were exercise intolerant. Median creatine kinase (CK) level of patients at the day of MRI was 398 U/L (range 35-12,483). T1W and STIR signal intensity (SI) were markedly increased in MTPD patients from girdle to lower leg. VLCADD patients showed predominantly proximal T1W SI changes, whereas LCHADD patients mostly showed distal T1W SI changes. Prominent STIR weighted signal intensity increases of almost all muscle groups were observed in patients with VLCADD and LCHADD with very high CK (>11.000) levels.

CONCLUSIONS AND RELEVANCE

lcFAO disorders are associated with specific patterns of increased T1W and STIR signal intensity. These patterns may reflect lipid accumulation and inflammation secondary to lcFAO defects and progressive muscle damage. Future studies are needed to investigate whether muscle MRI might be a useful tool to monitor disease course and to study pathogenesis of lcFAO related myopathy.