Current understanding and progress of research on isovaleric acidemia / 中华医学遗传学杂志

Isovaleric acidemia is a type of organic acidemia for which the earliest definite diagnosis was attained. It features an autosomal recessive inheritance, with the onset of age varying from newborn to adulthood. The clinical manifestations are complex and variable, which include feeding difficulty, vomiting, lethargy, coma, metabolic acidosis, sweaty feet odor and mental retardation. The mortality and mobility rates of isovaleric acidemia are quite high, and early diagnosis and rational treatment can significantly improve the prognosis. This article has provided a summary for the current understanding and research progress on isovaleric acidemia.

Isovaleric acidemia due to compound heterozygous variants of IVD gene in a case / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical features, biochemical characteristics and molecular pathogenesis of a girl with isovaleric acidemia.@*METHODS@#Clinical features, blood spot amino acid profiles and urinary organic acid profiles of the patient were analyzed. Targeted capture, next generation sequencing and Sanger sequencing were carried out to detect potential variant of the IVD gene.@*RESULTS@#The patient presented with poor weight gain, poor feeding, lethargy, and a "sweaty feet" odor 10 days after birth. Biochemical test suggested hyperammonemia. Blood spot amino acid profiles displayed a dramatic increase in isovalerylcarnitine (C5: 3. 044, reference range 0.04 - 0.4 μmol/L). Organic acid analysis of her urine sample revealed a high level of isovaleric glycine (669. 53, reference range 0 - 0.5). The child was ultimately diagnosed with isovaleric acidemia, and was found to harbor a paternally derived heterozygous variant c.149G>A (p.R50H) and a maternally derived heterozygous variant c.1123G>A (p.G375S) of the IVD gene. Her elder brother was a heterozygous carrier of c.1123G>A (p.G375S) variant. The c.149G>A (p.R50H) was a known pathogenic variant, while the c.1123G>A (p.G375S) variant was previously unreported.@*CONCLUSION@#The pathogenesis of the patient was delineated from the perspective of genetics, which has provided a basis for clinical diagnosis, treatment as well as genetic counseling.

Screening and clinical analysis of isovaleric acidemia newborn in Zhejiang province / 浙江大学学报·医学版

OBJECTIVE@#To investigate the incidence,clinical,biochemical and genetic characteristics of isovaleric acidemia (IVA) in Zhejiang province.@*METHODS@#Between January 2009 and December 2019, a total of 3 510 004 newborns were screened for IVA using tandem mass spectrometry. Patients of IVA were confirmed by urine organic acid and @*RESULTS@#A total of 15 patients with IVA were diagnosed, with an incidence of 1/234 000. Three patients had acute neonatal IVA, and the rest were asymptomatic. The isovalerylcarnitine (C5) levels were increased in all patients. Twelve children underwent urinary organic acid analysis, of which 11 cases had elevated isovalerylglycine levels, 4 cases with 3-hydroxyisovalerate increased simultaneously. Eleven IVA patients underwent genetic testing, 9 patients were compound heterozygous variants in @*CONCLUSIONS@#The clinical manifestations of IVA are non-specific, and the gene spectrum is scattered. Newborn patients screened by tandem mass spectrometry can receive early diagnosis and treatment, so as to correct metabolic defects and pathophysiological changes.

A Rare Cause of Recurrent Acute Pancreatitis in a Child: Isovaleric Acidemia with Novel Mutation / 대한소아소화기영양학회지

Recurrent acute pancreatic attacks is a rare clinical condition (2-5% of all acute pancreatis) in children and is mainly idiopathic in most cases. Sometimes it may be associated with congenital anomalies, metabolic diseases or hereditary conditions. Isovaleric acidemia (IVA) is a rare autosomal recessive amino acid metabolism disorder associated with isovaleryl coenzyme A dehydrogenase deficiency presenting the clinical findings such metabolic acidosis with increased anion gap, hyperammonemia, ketonemia, hypoglycemia, “the odor of sweaty feet,” abdominal pain, vomiting, feeding intolerance, shock and coma. Recurrent acute pancreatitis associated with IVA have been rarely reported. Herein; we report a child who admitted with recurrent acute pancreatic attacks and had the final diagnosis of IVA. Mutation analysis revealed a novel homozygous mutation of (p.E117K [c.349G>A]) in the IVA gene. Organic acidemias must kept in mind in the differential diagnosis of recurrent acute pancreatic attacks in children.

Pancytopenia and metabolic decompensation in a neonate / 中国当代儿科杂志

A 9-day-old male patient was admitted to the hospital because of cough, anhelation, feeding difficulty and lethargy. The diagnostic examinations indicated pulmonary infection, severe metabolic acidosis, hyperglycemia, hyperammonemia and pancytopenia in the patient. Blood and urine screening and isovaleryl-CoA dehydrogenase (IVD) gene detection for inherited metabolic diseases were performed to clarify the etiology. Tandem mass spectrometric screening for blood showed an elevated isovalerylcarnitine (C5) level. The organic acid analysis of urine by gas chromatography-mass spectrometry showed significantly increased levels in isovaleryl glycine and 3-hydroxyisovaleric acid. Homozygous mutations (c.1208A>G, p.Tyr403Cys) in the IVD gene were identified in the patient. His parents were heterozygous carriers. After the treatment with low-leucine diets and L-carnitine for 3 days, the patient showed a significant improvement in symptoms, but he died one week later. It is concluded that the neonates with pneumonia and metabolic decompensation of unknown etiology should be screened for genetic metabolic disease.

Chronic intermittent form of isovaleric aciduria in a 2-year-old boy / 소아과

Isovaleric aciduria (IVA) is caused by an autosomal recessive deficiency of isovaleryl-CoA dehydrogenase (IVD). IVA presents either in the neonatal period as an acute episode of fulminant metabolic acidosis, which may lead to coma or death, or later as a "chronic intermittent form" that is associated with developmental delays, with or without recurrent acidotic episodes during periods of stress, such as infections. Here, we report the case of a 2-year old boy with IVA who presented with the chronic intermittent form. He was admitted to Asan Medical Center Children's Hospital with recurrent vomiting. Metabolic acidosis, hyperammonemia, elevated serum lactate and isovalerylcarnitine levels, and markedly increased urine isovalerylglycine concentration were noted. Sequence analysis of the IVD gene in the patient revealed the novel compound mutations-a missense mutation, c.986T>C (p.Met329Thr) and a frameshift mutation, c.1083del (p.Ile361fs*11). Following stabilization during the acute phase, the patient has remained in a stable condition on a low-leucine diet.

Continuous Renal Replacement Therapy in a 4-year-old Child with Rhabdomyolysis Following Parainfluenza Virus Infection and Hyperammonemia due to Isovaleric Acidemia

Parainfluenza virus infection is one of the causes of fatal rhabdomyolysis. Rhabdomyolysis can be aggravated by mitochondrial fatty acid beta-oxidation disorders during prolonged periods of fasting. Moreover, in patients with late-onset isovaleric acidemia, hyperammonemia may occur following catabolic stress. In the present report, we describe a case of a 4-year-old boy with parainfluenza virus infection and late-onset isovaleric acidemia that rapidly progressed to coma, seizures, and cardiorespiratory collapse. His serum ammonia and creatinine kinase (CK) levels were 385 microMol/L and 23,707 IU/L, respectively. Continuous renal replacement therapy (CRRT) was initiated using continuous venovenous hemodiafiltration, after which the ammonia and CK levels returned to normal. Thus, we recommend the immediate initiation of CRRT in the management of patients with life-threatening rhabdomyolysis and hyperammonemia.

Inherited metabolic diseases in the urine organic acid analysis of complex febrile seizure patients / 소아과

PURPOSE: Seizure associated with fever may indicate the presence of underlying inherited metabolic diseases. The present study was performed to investigate the presence of underlying metabolic diseases in patients with complex febrile seizures, using analyses of urine organic acids. METHODS: We retrospectively analyzed and compared the results of urine organic acid analysis with routine laboratory findings in 278 patients referred for complex febrile seizure. RESULTS: Of 278 patients, 132 had no abnormal laboratory findings, and 146 patients had at least one of the following abnormal laboratory findings: acidosis (n=58), hyperammonemia (n=55), hypoglycemia (n=21), ketosis (n=12). Twenty-six (19.7%) of the 132 patients with no abnormal findings and 104 (71.2%) of the 146 patients with statistically significant abnormalities showed abnormalities on the organic acid analysis (P<0.05). Mitochondrial respiratory chain disorders (n=23) were the most common diseases found in the normal routine laboratory group, followed by PDH deficiency (n=2 ) and ketolytic defect (n=1). In the abnormal routine laboratory group, mitochondrial respiratory chain disorder (n=29) was the most common disease, followed by ketolytic defects (n=27), PDH deficiency (n=9), glutaric aciduria type II (n=9), 3-methylglutaconic aciduria type III (n=6), biotinidase deficiency (n=5), propionic acidemia (n=4), methylmalonic acidemia (n=2), 3-hydroxyisobutyric aciduria (n=2), orotic aciduria (n=2), fatty acid oxidation disorders (n=2), 2-methylbranched chain acyl CoA dehydrogenase deficiency (n=2), 3-methylglutaconic aciduria type I (n=1), maple syrup urine disease (n=1), isovaleric acidemia (n=1), HMG-CoA lyase deficiency (n=1), L-2-hydroxyglutaric aciduria (n=1), and pyruvate carboxylase deficiency (n=1). CONCLUSION: These findings suggest that urine organic acid analysis should be performed in all patients with complex febrile seizure and other risk factors for early detection of inherited metabolic diseases.

Clinical and mutational study of a Chinese infant with isovaleric acidemia / 中华儿科杂志

<p><b>OBJECTIVES</b>Isovaleric acidemia (IVA) is an autosomal recessive inborn error of leucine metabolism caused by a deficiency of the mitochondrial enzyme isovaleryl-CoA dehydrogenase (IVD) resulting in the accumulation of derivatives of isovaleryl-CoA. IVA is considered to be a severe, potentially life-threatening disorder that manifests with acute neonatal encephalopathy in approximately half of affected individuals, and recurrent episodes of vomiting, lethargy, coma and varying degrees of developmental delay in the other half of patients. This study was conducted to investigate the clinical features and IVD gene mutations of a Chinese patient with IVA.</p><p><b>METHODS</b>The clinical features, routine laboratory data, blood amino acid and acylcarnitine profiles and urinary organic acid profiles of a patient with IVA were reviewed. Whole coding exons of IVD gene were PCR-amplified for DNA sequencing. The novel mutation c.466G > C (G127A) was confirmed by RFLP with restriction endonuclease Hph I.</p><p><b>RESULTS</b>The patient was a 2 year and 7 month-old boy. At 3 days of age, he began to show severe vomiting and acidosis. He was treated with pyloromyotomy at 10 days of age. His recurrent vomiting was not ameliorated until beginning transition to a diet that included more carbohydrate from 4 months. He had 3 recurrent severe vomiting and acidosis later and showed obvious psychomotor retardation. Blood spot acylcarnitine profiles by MS-MS demonstrated an elevation of C5-carnitine with a peak concentration of 12.89 micromol/L (< 0.5 micromol/L). Organic acid analysis of urine by GC-MS revealed a relatively high level of isovaleric glycine. Mutational analysis of the patient's IVD gene revealed heteroallelic mutations of c.149G > A (R21H) and c.466G > C (G127A) which is a novel missense mutation. G127A mutation was not detected in any of 50 normal controls.</p><p><b>CONCLUSIONS</b>From the clinical course, obvious elevation of blood C5-carnitine and urine isovaleric glycine, this patient's disorder should be classified as "metabolically severe" type of IVA which suggest that c.466G > C (G127A) mutation could severely damage the function of the IVD protein. To our knowledge, this is the first characterization of IVD gene mutations in the mainland of China.</p>

Isovaleric Acidemia in Siblings Diagnosed by Organic Acid Analysis

Isovaleric acidemia is an inborn error in metabolism due to a defect in isovaleryl-CoA dehydrogenase. Accumulation of serum isovaleric acid causes poor feeding, vomiting, lethargy, hypothermia, convulsion, mental retardation, etc. It is inherited as an autosomal recessive trait. Since the first reports of isovaleric acidemia by Tanaka et al in 1966, more than 60 cases have been reported. There are two clinically different presentations of isovaleric acidemia, with about half the patients presenting with an acute severe neonatal form and about half with a chronic intermittent forrn. The difference in clinical presentation may not be a consequence of differing severities of the causative mutation, but a result of the timing of application of catabolic stress or the ability to form isovalerylglycine. We described here clinical and organic acid analytical findings of brothers with chronic intermittent form of isovaleric acidemia. (J Korean Pediatr Soc 2000;43:828-831)