Clinical Manifestations, Gene Analysis of Patients with 3-Methylcrotonyl-CoA Carboxylase Deficiency

OBJECTIVE: 3-Methylcrotonyl CoA carboxylase deficiency (3MCCD) is classified as organic acid disease due to leucine catabolism. It is among the most common inborn errors of metabolism identified on newborn screening test using tandem mass spectrometry. There is a broad spectrum of clinical presentations. 3-Methylcrotonyl CoA carboxylase converts 3-methylcrotonyl-CoA to 3-methylglutaconyl-CoA using biotin as a coenzyme in mitochondria. Restricting protein diets and supplementing carnitine, glycine, and biotin are known treatments. We reported this study to find out clinical symptoms, type of gene mutation, and effect of treatment. METHODS: This study was based on retrospective data of patients with 3MCCD in Soonchunhyang University Seoul Hospital and Soonchunhyang University Bucheon Hospital between April 2009 to August 2016. RESULTS: All 10 infants were born term infants and had no symptoms. During the neonatal period, abnormalities were detected in the new born screening test using tandem mass spectrometry, 3-hydroxyisovalerylcarnitine was increased. 3-Methylcrotonylglycine (3MCG) and 3-hydroxyisovalreric acid (3HIVA) were examined in urine organic acid assay. The results showed that 3MCG was increased in all 10 children. Except for three of the 10 children, 3HIVA was increased. Genetic tests were performed on all 10 children. MCCC1 gene mutations were detected in four patients and MCCC2 mutations were detected in six patients. After diagnosis, all children were recommended leucine-restricted diets, and seven of the 10 patients started to feed on leucine free formula for the treatment of 3MCCD. CONCLUSION: According to our data, all patients has no symptoms and are shown normal development. There were no clinical symptoms or changes in prognosis according to gene mutation type.

Novel heterozygous MCCC1 mutations identified in a patient with 3-methylcrotonyl-coenzyme A carboxylase deficiency

Isolated 3-methylcrotonyl-CoA carboxylase deficiency is an autosomal recessive disorder affecting leucine metabolism; it is one of the most common inborn metabolic diseases detected in newborn screening. Mutations in the genes MCCC1 or MCCC2 cause a defect in the enzyme 3-methylcrotonyl-CoA carboxylase, with MCCC2 mutations being the form predominantly reported in Korea. The majority of infants identified by neonatal screening usually appear to be asymptomatic and remain healthy; however, some patients have been reported to exhibit mild to severe metabolic decompensation and neurologic manifestations. Here we report the clinical features of a patient with asymptomatic 3-methylcrotonyl-CoA carboxylase deficiency and novel heterozygous MCCC1 mutations.

Asymptomatic maternal 3-methylcrotonylglycinuria detected by her unaffected baby's neonatal screening test / 소아과

3-methylcrotonyl-coenzyme A carboxylase (3MCC) deficiency is an autosomal recessive disorder in which leucine catabolism is hampered, leading to increased urinary excretion of 3-methylcrotonylglycine. In addition, 3-hydroxyisovalerylcarnitine levels increase in the blood, and the elevated levels form the basis of neonatal screening. 3MCC deficiency symptoms are variable, ranging from neonatal onset with severe neurological abnormality to a normal, asymptomatic phenotype. Although 3MCC deficiency was previously considered to be rare, it has been found to be one of the most common metabolic disorders in newborns after the neonatal screening test using tandem mass spectrometry was introduced. Additionally, asymptomatic 3MCC deficient mothers have been identified due to abnormal results of unaffected baby's neonatal screening test. Some of the 3MCC-deficient mothers show symptoms such as fatigue, myopathy, or metabolic crisis with febrile illnesses. In the current study, we identified an asymptomatic 3MCC deficient mother when she showed abnormal results during a neonatal screening test of a healthy infant.

Identification of a Novel Mutation in the MCCC2 Gene of a Korean Patient with 3-Methylcrotonyl-CoA Carboxylase Deficiency

3-methylcrotonyl-CoA carboxylase deficiency is an autosomal recessive disorder characterized by a defect in leucine catabolism. We report the case of an 80-day-old patient with 3-methylcrotonyl-CoA carboxylase deficiency who had elevated levels of 3-hydroxyisovalerylcarnitine (45.56 micromol/L; reference range, C (p.Gly105Arg)] at nucleotide position 313 and a mutation caused by a heterozygous A to T transversion [c.1252A>T (p.lle418Phe)] at nucleotide position 1252. Identification of these 2 novel MCCC2 gene mutations in our patient suggested that analysis of the MCCC1 and MCCC2 genes might prove useful in the diagnosis of 3-methylcrotonyl-CoA carboxylase deficiency.

Isolated 3-Methylcrotonyl CoA Carboxylase Deficiency Detected by Newborn Screening Program Using Tandem Mass Spectrometry / 소아과

Isolated deficiency of 3-methylcrotonyl CoA carboxylase is a rare disorder of the catabolic pathway for leucine and many patients have mild symptoms or no symptom. However, the introduction of tandem mass spectrometry in newborn screening has revealed an unexpectedly high incidence of this disorder. We report an asymptomatic premature infant with isolated 3-methylcrotonyl CoA carboxylase deficiency detected by newborn screening program using tandem mass spectrometry. She was born at preterm, 36 weeks of gestation and her birth weight was 1,912 gm. She was delivered by Cesarian section due to maternal preeclampsia and oligohydramnios. An elevation of 3-hydroxyisovalerylcarnitine in a blood sample obtained at Seven days was detected by tandem mass screening. Massively elevated excretion of 3-hydroxyisovalerate and 3-methylcrotonylglycine was detected in the urine collected at 15 days. L-carnitine(100 mg/kg/day) was administrated orally to correct sencondary carnitine deficiency. Carnitine is conjugated with metabolites, to decrease the potential toxic effects. She is asymptomatic to date, and her growth and development are within normal limits.

A Case of Asymptomatic 3-methylcrotonylglycinuria Detected by Tandem Mass Spectrometry in Newborn Screening / 소아과

3-Methylcrotonylglycinuria is an autosomal recessive inborn error of leucine catabolism that results from the deficiency of 3-methylcrotonyl-CoA carboxylase(3-MCC). In 3-MCC deficiency 3-methylcrotonyl-CoA, may form glycine and carnitine conjugates. The primary metabolites are 3-hydroxyisovaleric acid(3-HIVA), 3-hydroxyisovaleryl carnitine(3-HIVC) and 3-methylcrotonylglycine(3-MCG). 3-hydroxyisovaleric acid(3-HIVA) and 3-methylcrotonylglycine(3-MCG) are increased in urine, and 3-hydroxyisovaleryl carnitine(3-HIVC) is found in blood and urine. 3-MCC is one of the four biotin- dependent carboxylases known in humans and is a heteromeric mitochondrial enzyme comprised of biotin-containing alpha-subunits and smaller beta-subunits. The gene for alpha-subunits(MCCC1) is located on chromosome 3q25-q27, beta-subunits(MCCC2) is located in 5q12-q13. Mutation in either of these genes may result in the deficiency of the enzyme activity. The introduction of tandem mass spectrometry in newborn screening has revealed an unexpectedly high incidence of this disorder and has also revealed that the range of clinical symptoms has become even wider ranging from neonatal onset with severe neurological involvement to asymptomatic newborns and adults. We report a case of a 43-day-old Korean asymptomatic girl with 3-Methylcrotonylglycinuria, detected by tandem mass spectrometry in newborn screening. This is resulted from the deficiency of 3-MCC by urine organic acid analysis. We found 2 mutations in the MCC2 gene of this patient. They are misssence mutation (D280Y) and splicing mutation(T357T). This patient on leucine restriction in conjunction with oral carnitine and glycine shows normal growth and development until now(10 months).

A Case of Lennox-Gastaut Syndrome due to 3-Methylcrotonyl CoA Carboxylase Deficiency

3-Methylcrotonyl-CoA carboxylase(MCC) is a biotin-dependent enzyme involved in the leucine metabolism. We describe a patient with MCC deficiency who manifested with Reye syndrome-like illness with status epilepticus, metabolic acidosis, hypoglycemia, hyperammonemia, elevated liver enzymes and neurologic impairments after a viral gastroenteritis and then suffered from Lennox-Gastaut syndrome. Urinary organic acid analysis revealed increased excretions of 3-hydroxyisovaleric acid and 3-methylcrotonylglycine. This patient was managed with a leucine restriction diet and supplementation of biotin and carnitine, which was not so effective. He suffered from neurologic sequelae such as Lennox-Gastaut syndrome, motor and cognitive impairements.