Use of a long-chain triglyceride-restricted/medium-chain triglyceride-supplemented diet in a case of malonyl-CoA decarboxylase deficiency with cardiomyopathy

Clinical, biochemical and genetic characteristics and long-term follow-up of five patients with malonyl-CoA decarboxylase deficiency

BACKGROUND

Malonyl-CoA decarboxylase (MLYCD) deficiency, also known as malonic aciduria (MAD), is a rare autosomal recessive inherited metabolic defect. In this study, we aimed to investigate the clinical and molecular features of five patients with MAD in order to increase clinicians' awareness of the disease.

METHODS

Sanger sequencing was used to detect and genetically analyze the MLYCD variations in the preexisting patients and their parents.

RESULTS

Five patients with MAD (5 months to 9.6 years old; two males and three females) rarely exhibited metabolic decompensation episodes or seizures. All patients exhibited varying degrees of developmental delay and hypotonia. Our study expands the spectrum of variants of the MLYCD gene. MLYCD gene variations were detected in all five patients, and five new variants were identified: c.60delG (p.Arg21Glyfs*52), c.928C > T (p.Arg310*), c.1293G > T (p.Trp431Cys), c.721T > C (p.Ser241Pro), and Exons 4-5 deletion. Additionally, there is no correlation between various genotypes and phenotypes.

CONCLUSION

A high-medium-chain triglyceride and low-long-chain triglyceride diet supplemented with L-carnitine was effective in most patients and may improve cardiomyopathy and muscle weakness. Newborn screening may aid in the early diagnosis, treatment, and prognosis of this rare disorder.

Cardiovascular involvement in later-onset malonyl-CoA decarboxylase deficiency: Case studies and literature review

BACKGROUND

Malonyl-CoA decarboxylase deficiency (MLYCDD) is an ultra-rare inherited metabolic disorder, characterized by multi-organ involvement manifesting during the first few months of life. Our aim was to describe the clinical, biochemical, and genetic characteristics of patients with later-onset MLYCDD.

METHODS

Clinical and biochemical characteristics of two patients aged 48 and 29 years with a confirmed molecular diagnosis of MLYCDD were examined. A systematic review of published studies describing the characteristics of cardiovascular involvement of patients with MLYCDD was performed.

RESULTS

Two patients diagnosed with MLYCDD during adulthood were identified. The first presented with hypertrophic cardiomyopathy and ventricular pre-excitation and the second with dilated cardiomyopathy (DCM) and mild-to-moderate left ventricular (LV) systolic dysfunction. No other clinical manifestation typical of MLYCDD was observed. Both patients showed slight increase in malonylcarnitine in their plasma acylcarnitine profile, and a reduction in malonyl-CoA decarboxylase activity. During follow-up, no deterioration of LV systolic function was observed. The systematic review identified 33 individuals with a genetic diagnosis of MLYCDD (median age 6 months [IQR 1-12], 22 males [67%]). Cardiovascular involvement was observed in 64% of cases, with DCM the most common phenotype. A modified diet combined with levocarnitine supplementation resulted in the improvement of LV systolic function in most cases. After a median follow-up of 8 months, 3 patients died (two heart failure-related and one arrhythmic death).

CONCLUSIONS

For the first time this study describes a later-onset phenotype of MLYCDD patients, characterized by single-organ involvement, mildly reduced enzyme activity, and a benign clinical course.

Case report: A novel 5'-UTR-exon1-intron1 deletion in MLYCD in an IVF child with malonyl coenzyme A decarboxylase deficiency and literature review

The subject of the study is an 11-month old IVF baby girl with the typical clinical manifestation of malonyl coenzyme A decarboxylase deficiency, including developmental delay, limb weakness, cardiomyopathy, and excessive excretion of malonic acid and methylmalonic acid. Whole genome sequencing (WGS) revealed a novel heterozygous nonsense mutation (c.672delG, p.Trp224Ter) in the MLYCD gene of the proband and her father and a novel heterozygous deletion in 5'-UTR-exon1-intron1 of the MLYCD gene of the proband and her mother. The patient's cardiac function and limb weakness improved considerably after 3 months of a low-fat diet supplemented with L-carnitine. Furthermore, mapping of gene mutations and clinical manifestations was done by case collection.

A case of malonyl coenzyme A decarboxylase deficiency with novel mutations and literature review

Introduction

Malonyl coenzyme A decarboxylase deficiency is caused by an abnormality in the MLYCD gene. The clinical manifestations of the disease involve multisystem and multiorgan.

Methods

We collected and analyzed a patient's clinical characteristics, genetic chain of evidence and RNA-seq. We use the search term "Malonyl-CoA Decarboxylase Deficiency" on Pubmed to collect cases reported.

Results

We report a 3-year-old girl who is presented with developmental retardation, myocardial damage and elevated C3DC. High-throughput sequencing identified heterozygous mutation (c.798G>A, p.Q266?) in the patient inherited from her father. The other heterozygous mutation (c.641+5G>C) was found in the patient inherited from her mother. RNA-seq showed that there were 254 differential genes in this child, among which 153 genes were up-regulated and 101 genes were down-regulated. Exon jumping events occurred in exons encoding PRMT2 on the positive chain of chromosome 21, which led to abnormal splicing of PRMT2. (P<0.05, FDR<0.05). The result of SNP showed that there were multiple mutation sites on chromosome 1, which may affect the downstream gene variation at the DNA level. The literature review identified 54 cases described since 1984.

Discussion

It is the first report about the locus, adding a new item to the MLYCD mutation library. Developmental retardation and cardiomyopathy are the most common clinical manifestations, with commonly elevated malonate and malonyl carnitine levels in children.

Heterogenous Clinical Landscape in a Consanguineous Malonic Aciduria Family

Malonic aciduria is an extremely rare inborn error of metabolism due to malonyl-CoA decarboxylase deficiency. This enzyme is encoded by the MLYCD (Malonyl-CoA Decarboxylase) gene, and the disease has an autosomal recessive inheritance. Malonic aciduria is characterized by systemic clinical involvement, including neurologic and digestive symptoms, metabolic acidosis, hypoglycemia, failure to thrive, seizures, developmental delay, and cardiomyopathy. We describe here two index cases belonging to the same family that, despite an identical genotype, present very different clinical pictures. The first case is a boy with neonatal metabolic symptoms, abnormal brain MRI, and dilated cardiomyopathy. The second case, the cousin of the first patient in a consanguineous family, showed later symptoms, mainly with developmental delay. Both patients showed high levels of malonylcarnitine on acylcarnitine profiles and malonic acid on urinary organic acid chromatographies. The same homozygous pathogenic variant was identified, c.346C > T; p. (Gln116*). We also provide a comprehensive literature review of reported cases. A review of the literature yielded 52 cases described since 1984. The most common signs were developmental delay and cardiomyopathy. Increased levels of malonic acid and malonylcarnitine were constant. Presentations ranged from neonatal death to patients surviving past adolescence. These two cases and reported patients in the literature highlight the inter- and intrafamilial variability of malonic aciduria.

Cardiac Complications of Propionic and Other Inherited Organic Acidemias

Clinical observations and experimental studies have determined that systemic acid-base disturbances can profoundly affect the heart. A wealth of information is available on the effects of altered pH on cardiac function but, by comparison, much less is known about the actions of the organic anions that accumulate alongside H⁺ ions in acidosis. In the blood and other body fluids, these organic chemical species can collectively reach concentrations of several millimolar in severe metabolic acidoses, as in the case of inherited organic acidemias, and exert powerful biological actions on the heart that are not intuitive to predict. Indeed, cardiac pathologies, such as cardiomyopathy and arrhythmia, are frequently reported in organic acidemia patients, but the underlying pathophysiological mechanisms are not well established. Research efforts in the area of organic anion physiology have increased dramatically in recent years, particularly for propionate, which accumulates in propionic acidemia, one of the commonest organic acidemias characterized by a high incidence of cardiac disease. This Review provides a comprehensive historical overview of all known organic acidemias that feature cardiac complications and a state-of-the-art overview of the cardiac sequelae observed in propionic acidemia. The article identifies the most promising candidates for molecular mechanisms that become aberrantly engaged by propionate anions (and its metabolites), and discusses how these may result in cardiac derangements in propionic acidemia. Key clinical and experimental findings are considered in the context of potential therapies in the near future.

Short-chain fatty acid, acylation and cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Metabolic dysfunction is a fundamental core mechanism underlying CVDs. Previous studies generally focused on the roles of long-chain fatty acids (LCFAs) in CVDs. However, a growing body of study has implied that short-chain fatty acids (SCFAs: namely propionate, malonate, butyrate, 2-hydroxyisobutyrate (2-HIBA), β-hydroxybutyrate, crotonate, succinate, and glutarate) and their cognate acylations (propionylation, malonylation, butyrylation, 2-hydroxyisobutyrylation, β-hydroxybutyrylation, crotonylation, succinylation, and glutarylation) participate in CVDs. Here, we attempt to provide an overview landscape of the metabolic pattern of SCFAs in CVDs. Especially, we would focus on the SCFAs and newly identified acylations and their roles in CVDs, including atherosclerosis, hypertension, and heart failure.

A Korean child diagnosed with malonic aciduria harboring a novel start codon mutation following presentation with dilated cardiomyopathy

BACKGROUND

Malonic aciduria (MA, OMIM#248360) is an extremely rare inherited metabolic disorder caused by the deficiency of malonyl-CoA decarboxylase. The phenotype exhibited by patients with MA is variable, but may include symptoms, such as developmental delay in early childhood, seizures, vomiting, metabolic acidosis, hypoglycemia, ketosis, and cardiomyopathy. We describe the first case of a Korean child with MA who presented with dilated cardiomyopathy (DCMP) at the age of 3 months.

METHODS AND RESULTS

A 3-month-old Korean boy visited our hospital for diagnosis and management of cardiomegaly. Newborn screening for inherited metabolic diseases showed a normal result; therefore, DCMP management was initiated. Biochemical and the MLYCD gene analyses subsequently confirmed diagnosis of MA. Elevated plasma C3DC level and excessive excretion of urinary malonate were observed, and two pathogenic variants, including a novel start codon mutation (c.1A>G), were identified in MLYCD. A low long-chain fat diet with middle-chain triglyceride formula and L-carnitine supplementation was initiated. The patient is now 5 years old and exhibits considerably improved cardiac function.

CONCLUSIONS

MA can be diagnosed using newborn screening; however, negative results do not exclude the possibility of disease. Metabolic screening for differential diagnosis of infantile DCMP is recommended to rule out rare, but manageable, metabolic cardiomyopathies.

A novel frameshift mutation of malonyl-CoA decarboxylase deficiency: clinical signs and therapy response of a late-diagnosed case

We evaluate the clinical findings and the treatment response of a late‐diagnosed case with a novel homozygous insertion c.13_14insG (p.P6Afs*202) result in a frameshift mutation in MLYCD gene. Both cardiac and neurologic involvements were mild when compared to previously reported cases, and see low‐fat/high‐carbohydrate diet treatment is highly effective.

A new case of malonyl-CoA decarboxylase deficiency with mild clinical features

Malonyl-CoA decarboxylase deficiency is an extremely rare autosomal recessive inborn error of fatty acid metabolism. It usually follows a severe disease course and presents poor prognosis without treatment. Here, we report an affected female juvenile with a mild clinical and biochemical phenotype who mainly featured poor schooling without cardiomyopathy and metabolic acidosis. She was suspected of malonyl-CoA decarboxylase deficiency due to a 57-kb deletion in 16q23.3 encompassing the MLCYD gene revealed by chromosome microarray. Malonyl-CoA decarboxylase deficiency was then confirmed by acylcarnitine analysis and organic acid analysis. Real-time PCR analysis of the patient revealed the first three exon deletion of the MLYCD gene, which was maternally inherited. DNA sequencing of the MLYCD gene of the patient identified a novel heterozygous mutation (c.911G>A, p.G304E) in exon 4 that was paternally inherited. The patient urine malonic acid dissolved and had a better school record in 6 month after initiation of fat-limited diet. At 1 year post treatment, the blood malonylcarnitine level decreased remarkably. Our result expands the phenotype of malonyl-CoA decarboxylase deficiency and suggests attentions should be paid to the mild form of disorders, for example, malonyl-CoA decarboxylase deficiency, which usually present a severe disease course.

Malonyl-CoA decarboxylase deficiency: long-term follow-up of a patient new clinical features and novel mutations

BACKGROUND

Malonyl-CoA decarboxylase (MLYCD, EC 4.1.1.9) deficiency is a rare autosomal recessive disorder that is widely diagnosed by neonatal screening.

METHODS

We report long term follow up of a patient with MLYCD deficiency showing signs of neonatal hypoglycemia, mental retardation, developmental delay and rheumatoid arthritis. Brain MRI revealed patchy, symmetrical hyperintensity of the deep white matter with periventricular white matter and subcortical arcuate fibers being spared. MLCYD gene sequence analysis was done to identify possible mutations. Expression analyses at mRNA and protein levels were also performed. Further, immunocytochemical studies were implemented to check for its subcellular localization.

RESULTS

MLYCD gene sequencing identified a novel compound heterozygous mutation (c.22 T>A, p.M1K, c.454 C>A; pH152N) in our patient and a heterozygous mutation in the healthy mother c.22 T>A; pM1K. Reduced expression of RNA and protein levels was observed. Immunocytochemical analysis showed diffused staining across the cytoplasm with apparent signs of intracellular mislocalization to the nucleus. RESULTS also indicated subcellular colocalization of MLCYD with mitochondria was scant compared to control.

CONCLUSION

Our patient was identified with a novel compound heterozygous MLYCD mutation at the N-terminal helical domain. This study indicates that protein mislocalization is a characteristic feature of MLYCD deficiency in our patient.

Malonic aciduria: long-term follow-up of new patients detected by newborn screening

Malonic aciduria is an extremely rare autosomal recessive inborn error of metabolism. We present clinical, biochemical and genetic information for several years of follow-up of new malonic aciduria patients who were diagnosed by newborn screening. These data are discussed with regard to treatment options and possible diagnostic pitfalls. The cases presented here show that the course of malonic aciduria is unpredictable and can even significantly differ in two siblings harbouring identical mutations. Early treatment can lead to the rapid improvement of cardiomyopathy in the course of malonic aciduria. Biochemical parameters seem to be variable and can intermittently be undetectable in the blood or urine samples of affected patients. Therefore, confirmatory tests following a positive newborn screening should be taken with caution and include both malonyl carnitine detection in dried blood spots and urinary organic acid analysis as initial measures.

CONCLUSION

Patients with a suspected or confirmed diagnosis of malonic aciduria should undergo thorough diagnostic procedures and be regularly screened for complications such as cardiomyopathy even when they are asymptomatic in order to ensure early therapy of treatable complications.

Cardiac dysfunction and peri-weaning mortality in malonyl-coenzyme A decarboxylase (MCD) knockout mice as a consequence of restricting substrate plasticity

Inhibition of malonyl-coenzyme A decarboxylase (MCD) shifts metabolism from fatty acid towards glucose oxidation, which has therapeutic potential for obesity and myocardial ischemic injury. However, ~40% of patients with MCD deficiency are diagnosed with cardiomyopathy during infancy.

AIM

To clarify the link between MCD deficiency and cardiac dysfunction in early life and to determine the contributing systemic and cardiac metabolic perturbations.

METHODS AND RESULTS

MCD knockout mice ((-/-)) exhibited non-Mendelian genotype ratios (31% fewer MCD(-/-)) with deaths clustered around weaning. Immediately prior to weaning (18days) MCD(-/-) mice had lower body weights, elevated body fat, hepatic steatosis and glycogen depletion compared to wild-type littermates. MCD(-/-) plasma was hyperketonemic, hyperlipidemic, had 60% lower lactate levels and markers of cellular damage were elevated. MCD(-/-) hearts exhibited hypertrophy, impaired ejection fraction and were energetically compromised (32% lower total adenine nucleotide pool). However differences between WT and MCD(-/-) converged with age, suggesting that, in surviving MCD(-/-) mice, early cardiac dysfunction resolves over time. These observations were corroborated by in silico modelling of cardiomyocyte metabolism, which indicated improvement of the MCD(-/-) metabolic phenotype and improved cardiac efficiency when switched from a high-fat diet (representative of suckling) to a standard post-weaning diet, independent of any developmental changes.

CONCLUSIONS

MCD(-/-) mice consistently exhibited cardiac dysfunction and severe metabolic perturbations while on a high-fat, low carbohydrate diet of maternal milk and these gradually resolved post-weaning. This suggests that dysfunction is a common feature of MCD deficiency during early development, but that severity is dependent on composition of dietary substrates.

A new case of malonic aciduria with a presymptomatic diagnosis and an early treatment

Malonyl-CoA decarboxylase deficiency (MLYCD) is a rare autosomal recessive inborn error of metabolism presenting a variable clinical phenotype. We report an affected Italian male receiving an early diagnosis (8days after birth) and a timely dietary therapy (high carbohydrate, low long chain fatty acid and medium chain triglyceride supplemented diet with l-carnitine supplementation). The boy was born at term and presented normal function of the heart (except for a tricuspid Ebstein-like dysplasia) and neurodevelopmental status. Genomic sequencing of MLYCD gene revealed two point mutations (c.672G>A, c.869C>T) not listed in the Human MLYCD Allelic Variant Database nor in Human Gene Mutation Database, responsible for a deleterious effect on protein structure and function according to a computational analysis (MuPro, SIFT, ConSEQ v1.1). At the age of 2years he only showed a mild language and psychomotor delay, while heart functioning became normal. Brain MRI examination was normal. Thirty-five cases, including our patient, have been described to date. This is the first report concerning a malonic aciduria patient diagnosed on newborn screening and treated in a presymptomatic stage of the disease.

Malonyl coenzyme A decarboxylase deficiency: early dietary restriction and time course of cardiomyopathy

Malonyl coenzyme A (CoA) decarboxylase (MCD) deficiency is a rare autosomal recessive organic acidemia characterized by varying degrees of organ involvement and severity. MCD regulates fatty acid biosynthesis and converts malonyl-CoA to acetyl-CoA. Cardiomyopathy is 1 of the leading causes of morbidity and mortality in this disorder. It is unknown if diet alone prevents cardiomyopathy development based in published literature. We report a 10-month-old infant girl identified by newborn screening and confirmed MCD deficiency with a novel homozygous MLYCD mutation. She had normal echocardiogram measurements before transition to high medium-chain triglycerides and low long-chain triglycerides diet. Left ventricular noncompaction development was not prevented by dietary interventions. Further restriction of long-chain triglycerides and medium-chain triglycerides supplementation in combination with angiotensin-converting enzyme inhibitors helped to improve echocardiogram findings. Patient remained asymptomatic, with normal development and growth. Our case emphasizes the need for ongoing cardiac disease screening in patients with MCD deficiency and the benefits and limitations of current dietary interventions.