Heterogeneous phenotypes, genotypes, treatment and prevention of 1 003 patients with methylmalonic acidemia in the mainland of China / 中华儿科杂志

Objective@#To analyz the current situation of the diagnosis, treatment and prevention of methylmalonic acidemia, the phenotypes, biochemical features and genotypes of the patients in the mainland of China, were investigated.@*Methods@#Tottally 1 003 patients of methylmalonic acidemia from 26 provinces and municipalities of the mainland of China were enrolled. The clinical data, biochemical features and gene mutations were studied. Blood aminoacids and acylcarnitines, urine organic acids, and plasma total homocysteine were determined for the biochemical diagnosis. Gene analyses were performed for the genetic study of 661 patients. The patients were treated with individual intervention and long-term follow up. Prenatal diagnoses were carried out for 165 fetuses of the families.@*Results@#Among 1 003 patients (580 boys and 423 girls), 296 cases (29.5%) had isolated methylmalonic acidemia; 707 cases (70.5%) had combined homocysteinemia; 59 patients (5.9%) were detected by newborn screening; 944 patients (94.1%) had the onset at the ages from several minutes after birth to 25 years and diagnosed at 3 days to 25 years of age. The main clinical presentations were psychomotor retardation and metabolic crisis. Multi-organ damage, including hematological abnormalities, pulmonary hypertension, kidney damage, were found. MMACHC, MUT, MMAA, MMAB, HCFC1, SUCLG1, SUCLA2 mutations were found in 631 patients (96.6%) out of 661 patients who accepted gene analysis. MMACHC mutations were detected in 460 patients (94.7%) out of 486 cases of methylmalonic acidemia combined with homocysteinemia. MUT mutations were found in 158 (90.3%) out of 169 cases of isolated methylmalonic acidemia. The development of 59 patients detected by newborn screening were normal; 918 cases (97.2%) were diagnosed after onset accepted the treatment. Forty-five of them completely recovered with normal development. Twenty-six patients (2.7%) died; 873 (92.5%) patients had mild to severe psychomotor retardation. Methylmalonic acidemia were found in 35 out of 165 fetuses by metabolites assay of amniotic fluid and amniocytes gene analysis.@*Conclusion@#Combined methylmalonic acidemia and homocysteinemia is the common type of methylmalonic acidemia in the mainland of China. CblC defect due to MMACHC mutations is the most common type of methylmalonic acidemia combined with homocysteinemia. MUT gene mutations are frequent in the patients with isolated methylmalonic acidemia. Newborn screening is key for the early diagnosis and the better outcome. Combined diagnosis of biochemical assays and gene analysis are reliable for the prenatal diagnosis of methylmalonic acidemia.

Seven patients of argininemia with spastic tetraplegia as the first and major symptom and prenatal diagnosis of two fetuses with high risk / 中华儿科杂志

<p><b>OBJECTIVE</b>Argininemia is a rare disorder of urea cycle defect. The clinical manifestations of this disorder are similar to those of cerebral palsy so that the diagnosis is usually much delayed. This study aimed to investigate the phenotypes and genotypes of seven Chinese patients suffering from argininemia.</p><p><b>METHOD</b>Three boys and four girls with spastic tetraplegia were diagnosed as argininemia by blood aminoacids analysis and ARG1 gene study. Patients were given a protein-restricted diet, citrulline, sodium benzoate, and other treatment intervention. The mother of Patient 5 and 6 accepted genetic counseling and underwent prenatal diagnosis by amniocentesis.</p><p><b>RESULT</b>Seven patients presented with progressive spastic tetraplegia and poor physical growth from the age of 1 month to 4 years. Argininemia was found at the age of 1 year and 10 months to 12 years. Five patients had mental retardations. Three had seizures. Their blood arginine elevated (86.66 to 349.83 µmol/L, normal controls 5 to 25 µmol/L). Liver dysfunction was found in six patients. Five patients had elevated blood ammonia levels. In four patients, cerebral atrophy was observed by cranial magnetic resonance imaging. Nine mutations in the ARG1 gene were identified from 7 patients. Only two mutations, c.703G > A in exon 7 and c.32T > C in exon 1 had been reported. c.34G > T, c.53G > A, c.67delG, c.232dupG, c.374C > T, c.539G > C and c.646-649delCTCA, were novel mutations of ARG1. A homozygous mutation c.703G > A was found in the amniocytes of Patient 5's mother, indicating that the fetus was affected by argininemia. Induced abortion was performed. c.53G > A from Patient 6 was not found in the amniocytes of her mother, indicating that the fetus was not affected by hepatocyte arginase deficiency. The result was confirmed by postnatal mutation analysis of cord blood and the normal blood arginine of the newborn.</p><p><b>CONCLUSION</b>Argininemia is one of the few treatable causes of pediatric spastic paralysis. In this study, seven Chinese patients with spastic tetraplegia were detected by blood aminoacids analysis and confirmed by molecular analysis. Seven novel mutations on ARG1 gene were identified. Prenatal diagnosis of the fetus of a family was performed by amniocytes ARG1 gene analysis.</p>

Acute encephalopathy induced by vaccination in an infant with methylmalonic aciduria cblA / 中华儿科杂志

<p><b>OBJECTIVE</b>We report the first case of acute encephalopathy induced by vaccination in an infant with methylmalonic aciduria cblA in China.</p><p><b>METHOD</b>The clinical presentation, blood acylcarnitines analysis, urine organic acids analysis and gene studies of the patient were summarized.</p><p><b>RESULT</b>The proband, a boy, was admitted at the age of 15 months because of recurrent vomiting, acidosis and development delay for 8 months. The previously healthy boy presented vomiting and coma just one hour after hepatitis B vaccination at the age of seven months. Moderate dehydration, electrolyte disturbance and metabolic acidosis had been found. Although his acute metabolic crisis had been corrected soon after intravenous transfusion, psychomotor retardation and recurrent vomiting had been observed. When he was 15 months old, vomiting and lethargy occurred again 3 hours after DTaP vaccination. He was weakened as the illness became worse and got coma with dyspnea 7 days later. He was hospitalized with the suspected diagnosis of viral encephalitis. Blood acylcarnitines analysis, urine organic acids analysis and gene study had been performed for the etiologic investigation.His blood propionylcarnitine (16.3 µmol/L vs. normal range 1.0-5.0 µmol/L) and propionylcarnitine/free carnitine ratio (0.27 vs. normal range 0.03 to 0.25) increased. Markedly elevated urinary methylmalonic acid (388.21 mmol/mol creatinine vs. normal range 0.2 to 3.6 mmol/mol creatinine) and normal plasma total homocysteine supported the diagnosis of isolated methylmalonic aciduria. Two mutations, c.650 T>A (p.L217X) and c.742 C>T (p.Q248X), were identified in his MMAA gene, confirmed the diagnosis of cblA. Each parent carried one of the two mutations. Progressive clinical and biochemical improvement has been observed after hydroxylcobalamin injection, protein-restricted diet with the supplements of special formula and L-carnitine. He is currently 2 years and 7 months old with normal development and general condition.</p><p><b>CONCLUSION</b>A boy with cblA was firstly detected after the acute encephalopathy induced by vaccination in China. It is important to pay more attention to the patients with metabolic crisis or organ damage after vaccination. Metabolic studies are keys to the diagnosis of potential diseases and improve the outcome.</p>

Phenotypes and genotypes of 126 patients with isolated methylmalonic aciduria / 中华实用儿科临床杂志

Objective To investigate the clinical,biochemical and genetic findings in patients with isolated methylmalonic aciduria. Methods From January 2001 to December 2014,a total of 126 patients with isolated methyl-malonic aciduria from Peking University First Hospital were enrolled in this study. In 60 patients,gene analysis was per-formed. The clinical characteristics,laboratory findings,treatment and outcomes were retrospectively analyzed. Results Among the 126 patients,only 3 cases(2. 4% )were detected through newborn screening and treated with dietary in-tervention,cobalamin and L - camitine. The age at onset of 123 cases(97. 6% )varied from a few hours after birth to 7 years and 11 months old. The common presentations were recurrent vomiting,mental retardation,poor feeding,lethargy, respiratory distress,coma,seizures,cutaneous lesion and jaundice with 11 patients(8. 73% )dead. Abnormal family his-tory was found in 27(21. 4% )patients. Metabolic acidosis and anemia were frequent laboratory findings. Basal ganglia damage and white matter changes were observed in most patients. Sixty patients got genetic analysis,and 58 cases of them had MUT gene mutations. One case had MMAA defect. One case had MMAB defect. In MUT gene,12 novel muta-tions were identified. After treatment,mild to severe psychomotor retardation was observed in 112 patients with isolated methylmalonic aciduria. Conclusions The clinical manifestation of patients with isolated methylmalonic aciduria is complex,and prone to appear metabolic crisis. MUT defect is the main cause. Early metabolic investigation is very im-portant to reach diagnosis. Newborn screening,early diagnosis and adequate therapy are key points to reduce the morta-lity and handicap.

Clinical and laboratory studies on 28 patients with glutaric aciduria type 1 / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the clinical, biochemical and genetic profiles of 28 Chinese patients with glutaric aciduria type 1.</p><p><b>METHOD</b>Twenty-eight patients with glutaric aciduria type 1 seen in the Department of Pediatrics, Peking University First Hospital from July 2003 to October 2013 were studied. The data of clinical course, laboratory examinations, cranial MRI and GCDH gene mutations of the patients were analyzed.</p><p><b>RESULT</b>(1) Three cases were detected by newborn screening, and the other patients were diagnosed at the age of 2 months to 17 years. (2) 22 patients (79%) were infant onset cases with psychomotor retardation, dystonia, seizures, athetosis, recurrent vomiting, drowsiness or feeding difficulty. Only two of the 22 patients with infant onset got normal intelligence and movement after treatment. Twenty of them were improved slowly with delayed development, dystonia and other neurological problems. Three patients (11%) had late onset. They had motor regression, headache and seizure at the age of 8, 9 and 17 years, respectively. Rapid improvement was observed after treatment. (3) Cranial MRI has been checked in 23 patients; 22 of them showed characteristic widening of the Sylvian fissure, abnormalities of the basal ganglia, leukoencephalopathy and brain atrophy. Thirty-five mutations in GCDH gene of the patients were identified; c.148T>C (p.W50R) was the most common mutation with the frequency of 7.7%; 6 mutations (c.628A>G, c.700C>T, c.731G>T, c.963G>C, c.1031C>T and c.1109T>C) were novel.</p><p><b>CONCLUSION</b>Glutaric aciduria type 1 usually induced neurological deterioration resulting in severe psychomotor retardation and dystonia. Most of our patients were clinically diagnosed. Patients with early onset usually remained having neurological damage. Phenotype and genotype correlation has not been found in the patients. Neonatal screening for organic acidurias should be expanded in China.</p>

A case of neonatal death due to argininosuccinic aciduria / 临床儿科杂志

Objectives To report the ifrst Chinese case of early onset argininosuccinic aciduria. Methods A girl aged three days was admitted because of vomiting and lethargy from the second day of life. General laboratory examination, blood amino acids analysis, urine organic acids tests and gene studies were performed for the diagnosis. Results Severe hyperam-monemia, liver dysfunction, metabolic acidosis, hypokalemia and hypocalcemia were found. Bood citrulline was extremely elevated (1098.12μmol/L vs normal range 5 to 25μmol/L), while blood arginine was decreased. Urine orotic acid, uracil and argininosuccinic acid were signiifcantly elevated. Two known heterozygosis mutations on ASL gene, c.544C>T (p.R182X) and c.706C>T (p.R236W), conifrmed the diagnosis of argininosuccinic aciduria. Unfortunately, protein-restricted diet with L-arginine supplement showed no effect. The patient died at the 23th day of life. Conclusions Argininosuccinic aciduria is a severe inherit-ed metabolic disorder. Clinical diagnosis is dififcult. It is characterized biochemically by severe citrullinemia. Urine organic acids analysis and ASL gene analysis are important for the differential diagnosis. In this study, a case of neonate death due to early-on-set argininosuccinic aciduria was diagnosed by post-mortem investigation. ASL gene study is helpful for the genetic counseling and prenatal diagnosis of the disease.

Clinical and genetic features of three patients with non-classical isovaleric aciduria / 临床儿科杂志

Objective To explore the clinical, therapeutic and genetic features of IVD gene in late-onset non-classical isovaleric aciduria. Methods One boy and two girls presented with intractable vomiting were admitted. Urine organic acids and blood acylcarnitines proifles were analyzed. Isovaleric aciduria was diagnosed and conifrmed by IVD gene analysis. The patients were treated with leucine-restricted diet and the supplements of L-carnitine and glycine. Results Three patients had recurrent vomiting, drowsiness, odor of sweaty feet and metabolic acidosis from the age of 1 to 2 years. All of them had normal intelligence and leukopenia. One had oligocythemia. The blood isovalerylcarnitines (4.6 to 8.2μmol/L) and urine isovalerylglycines (36.1 to 1783.56 mmol/mmol creatinine) were elevated. Six mutations were found in their IVD gene. Four mutations (c.157C>T, c.214G>A, c.1183C>G and c.1208A>G) were reported. Two (c.1039G>A and c.1076A>G) were novel. The patients completely recovered after treatment with protein-restricted diet and the supplements of L-carnitine and glycine. Currently, they were aged 19 months to 14 years with normal physical and psychomotor development. Conclusions The clinical features of late-onset non-classical isovaleric aciduria are complex. It is onset in infants and young children and characteristic of recurrent vomiting and metabolic acidosis, which can be diagnosed by the blood acylcarnitine spectrum, urine organic acid analysis, and conifrmed by genetic analysis. L-carnitine supplement and diet intervention has signiifcant effects.

A Chinese girl with ethylmalonic encephalopathy and a novel mutation on ETHE1 gene / 临床儿科杂志

Objective To introduce a case of ethylmalonic encephalopathy which is an autosomal recessive metabolic disorder caused by mutations in the ETHE1 gene. Methods The clinical course and gene mutation in a case of ethylmalonic encephalopathy was retrospectively analysed. Results A previously healthy girl presented with intractable diarrhea from the age of 7 months. Since then, progressive psychomotor regression has been observed. When she was 23 months, her blood butyr-ylcarnitine was signiifcantly increased (4.48μmol/L vs. normal range 0.0~1.0μmol/L), and isovalerylcarnitine (0.70μmol/L vs. normal range 0.0~0.65μmol/L) was also elevated. Her urine levels of ethylmalonic acid and methylsuccinate acid were markedly increased. Cranial MRI revealed bilateral basal ganglia lesions supporting the diagnosis of ethylmalonic encephalopathy. On her ETHE1 gene, a reported mutation (c.488G>A, p.R163Q) and a novel mutation (c.203T>C, p.L68P) were identiifed. After lactose-free dietary treatment and the supplements of L-carnitine, coenzyme Q10, vitamins B1, B2 and C, gradual improvement in general condition, intelligence and motor development has been observed. Conclusions Ethylmalonic aciduria is common in the patients with inborn errors of mitochondrial fatty acid beta-oxidation. In ethylmalonic encephalopathy, elevated blood levels of butyrylcarnitine and isovalerylcarnitine are common and ETHE1 sequencing is helpful in its diagnosis.

HEXB gene study and prenatal diagnosis for a family affected by infantile Sandhoff disease / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the phenotype and genotype of a Chinese boy and his family affected by infantile Sandhoff disease.</p><p><b>METHODS</b>The proband, a boy, was the first child born to a non-consanguineous couple. He showed startle reaction after birth and progressive psychomotor regression from the age of 8 months. From the age of 16 months, he presented seizures. When he was admitted at 17 months old, severe mental retardation and weakness were observed. Fundus examination revealed bilateral cherry-red spots in the macula and optic atrophy. Cranial MRI revealed abnormal signals in the thalamus, basal ganglia and white matter. Enzymatic assay and genetic testing were performed for the diagnosis. His mother visited us at 18 weeks of pregnancy seeking for prenatal diagnosis. HEXB gene diagnosis to the fetus was performed by direct sequencing.</p><p><b>RESULTS</b>Significant deficient total β-hexosaminidase (A and B) activity in peripheral leucocytes of the patient (0.0 nmol/h/mg compared with normal control, 41.9 to 135.1 nmol/h/mg) supported the diagnosis of Sandhoff disease. On his HEXB gene, two mutations were found. c.1645G-A (p.G549R) was novel. c.IVS7-48T was a reported mutation. Now, the patient was 2 years and 3 months old, with progressive general failure, severe epilepsy, blindness and hypermyotonia. Subsequently, the mother visited us at 18 weeks of pregnancy seeking for prenatal diagnosis. HEXB gene analysis of the amniocytes was performed by direct sequencing. Both of the two mutations were not detected from cultured amniocytes. The result revealed that the fetus was not affected by Sandhoff disease. A healthy girl, the sibling of the proband, was born in term. Postnatal enzyme analysis and genetic analysis of the cord blood cells confirmed the prenatal diagnosis.</p><p><b>CONCLUSION</b>One novel mutation on HEXB gene was identified. Prenatal diagnosis to the fetus of this family was performed by amniocytes gene analysis.</p>