Mutations In MMACHC Gene Research Articles

Mutation spectrum and genotype-phenotype correlation of pediatric patients with methylmalonic acidemia.

MMA incidence is significantly greater in China than in the rest of the world, but the mutation spectrum of MMA in China has not yet been mapped. We summarized published MMA-related articles and conducted a systematic meta-analysis of the literature. We analyzed the gene variants information of 926 pediatric MMA patients in China; 517 were children with combined MMA, and 409 were children with isolated MMA. Almost all combined MMA cases were caused by MMACHC gene mutations (cblC-type). The c.609G>A variation was the most common in cblC-type children, accounting for 43.01%, followed by c.658_660delAAG, c.482G>A, c.80A>G, and c.394C>T variations. Mut-type MMA patients accounted for 98.8% (404/409) of all isolated MMA cases. The variant MMUT c.729_730insTT accounted for 10.30% (80/802) of all variants and was the most common variant in mut-type children, followed by c.323G>A and c.1106G>A. Our study summarized and characterized the mutation spectrum of Chinese pediatric patients with MMACHC and MMUT variants, and we also analyzed the relationships between common variants, onset time, and clinical phenotype. These findings will contribute to understanding the phenotypic characteristics and overall pathogenesis of MMA patients, supporting the goal of gene therapy. The incidence of methylmalonic academia (MMA) in China is significantly greater than that in the rest of the world, but the mutation spectrum of MMA in China has not yet been mapped. In this paper, for the first time, we investigated hot-spot gene variants in MMA patients in China and comprehensively described the MMA gene mutation spectrum of the Chinese population. We explored the relationship between MMA genotype and clinical phenotype in patients, providing a basis for family genetic counseling, prenatal diagnosis, and newborn screening.

Clinical, biochemical, molecular characteristics and clinical outcome of hyperhomocysteinemia in Malaysian children

BackgroundHyperhomocysteinemia can be due to various abnormalities of the complex interaction of methionine, folate and vitamin B12. It has been known to be a cardiovascular risk factor. This study aims to review the clinical presentation, underlying causes and clinical outcome in paediatric patients diagnosed with significant hyperhomocysteinemia in Malaysia. Design and methodsData were obtained from the medical records and the laboratory information system. Paediatric patients with significant hyperhomocysteinemia were identified from a selective high-risk screening of 96,721 patients, performed between 2010 and 2022. Inclusion criteria for the study were paediatric patients with significant hyperhomocysteinemia (>40 µmol/L). ResultsSixteen patients were identified. The average total homocysteine (tHcy) and methionine were 269 µmol/L and 499 µmol/L in cystathionine β-synthase deficiency (CBS), 127 µmol/L and 29 µmol/L in patients with remethylation defects and 390 µmol/L and 4 µmol/L in congenital B12 deficiency. We found c.609G>A as the most prevalent mutation in MMACHC gene and possible novel mutations for CBS (c.402del, c.1333C>T and c.1031T>G) and MTHFR genes (c.266T>A and c.1249del). Further subclassification revealed CBS was 5/16 patients (31 %), remethylation defects was 9/16 (56 %) and congenital B12 deficiency was 2/16 (13 %). All patients received standard treatment and regular monitoring of the main biomarkers. The average age at the time of diagnosis were 9.2 years (CBS) and 1.2 years (remethylation defects). Congenital B12 deficiency had slight delay in milestones, remethylation defects had mild to moderate learning disabilities, CBS had variable degree of intellectual disability, delayed milestones, ophthalmological abnormalities, and thrombosis at an early adolescent/adulthood. ConclusionsThe majority of significant hyperhomocysteinemia in Malaysian children was due to remethylation defects. Screening for hyperhomocysteinemia in Malaysian children is recommended for earlier treatment and improved clinical outcome.

Case presentation: a severe case of cobalamin c deficiency presenting with nephrotic syndrome, malignant hypertension and hemolytic anemia

BackgroundThe etiology of nephrotic syndrome can vary, with underlying metabolic diseases being a potential factor. Cobalamin C (cblC) defect is an autosomal recessive inborn error of metabolism caused by mutations in the MMACHC gene, resulting in impaired vitamin B12 processing. While cblC defect typically manifests with hematological and neurological symptoms, renal involvement is increasingly recognized but remains rare.Case PresentationWe describe a 7-month-old male patient presenting with fatigue and edema. His initial laboratory findings showed anemia, thrombocytopenia, hypoalbuminemia and proteinuria. Further examinations reveals hemolysis in peripheral blood smear. During his follow up respiratory distress due to pleural effusion in the right hemithorax was noticed. And fluid leakage to the third spaces supported a diagnosis of nephrotic syndrome. The patient’s condition deteriorated, leading to intensive care admission due to, hypertensive crisis, and respiratory distress. High total plasma homocysteine and low methionine levels raised suspicion of cobalamin metabolism disorders. Genetic testing confirmed biallelic MMACHC gene mutations, establishing the diagnosis of cblC defect. Treatment with hydroxycobalamin, folic acid, and betaine led to remarkable clinical improvement.Discussion/ConclusionThis case underscores the significance of recognizing metabolic disorders like cblC defect in atypical presentations of nephrotic syndrome. Early diagnosis and comprehensive management are vital to prevent irreversible renal damage. While cblC defects are more commonly associated with atypical hemolytic uremic syndrome, this case highlights the importance of considering cobalamin defects in the differential diagnosis of nephrotic syndrome, especially when associated with accompanying findings such as hemolysis. Our case, which has one of the highest homocysteine levels reported in the literature, emphasizes this situation again.

Clinical features and follow-up study on 55 patients with adolescence-onset methylmalonic acidemia

Objective: To investigate the clinical features and outcomes of adolescence-onset methylmalonic acidemia (MMA) and explore preventive strategies. Methods: This was a retrospective case analysis of the phenotypes, genotypes and prognoses of adolescence-onset MMA patients. There were 55 patients diagnosed in Peking University First Hospital from January 2002 to June 2023, the data of symptoms, signs, laboratory results, gene variations, and outcomes was collected. The follow-ups were done through WeChat, telephone, or clinic visits every 3 to 6 months. Results: Among the 55 patients, 31 were males and 24 were females. The median age of onset was 12 years old (range 10-18 yearsold). They visited clinics at Tanner stages 2 to 5 with typical secondary sexual characteristics. Nine cases (16%) were trigged by infection and 5 cases (9%) were triggered by insidious exercises. The period from onset to diagnosis was between 2 months and 6 years. Forty-five cases (82%) had neuropsychiatric symptoms as the main symptoms, followed by cardiovascular symptoms in 12 cases (22%), kidney damage in 7 cases (13%), and eye disease in 12 cases (22%). Fifty-four cases (98%) had the biochemical characteristics of methylmalonic acidemia combined with homocysteinemia, and 1 case (2%) had the isolated methylmalonic acidemia. Genetic diagnosis was obtained in 54 cases, with 20 variants identified in MMACHC gene and 2 in MMUT gene. In 53 children with MMACHC gene mutation,1 case had dual gene variants of PRDX1 and MMACHC, with 105 alleles. The top 5 frequent variants in MMACHC were c.482G>A in 39 alleles (37%), c.609G>A in 17 alleles (16%), c.658_660delAAG in 11 alleles (10%), c.80A>G in 10 alleles (10%), c.567dupT and c.394C>T both are 4 alleles (4%). All patients recovered using cobalamin, L-carnitine, betaine, and symptomatic therapy, and 54 patients (98%) returned to school or work. Conclusions: Patients with adolescence-onset MMA may triggered by fatigue or infection. The diagnosis is often delayed due to non-specific symptoms. Metabolic and genetic tests are crucial for a definite diagnosis. Treatment with cobalamin, L-carnitine, and betaine can effectively reverse the prognosis of MMA in adolescence-onset patients.

Clinical and electroencephalogram characteristics of methylmalonic acidemia with MMACHC and MUT gene mutations

ObjectiveThis study investigated the clinical, imaging, and electroencephalogram (EEG) characteristics of methylmalonic acidemia (MMA) with nervous system damage as the primary manifestation.MethodsFrom January 2017 to November 2022, patients with nervous system injury as the main clinical manifestation, diagnosed with methylmalonic acidemia by metabolic and genetic testing, were enrolled and analyzed. Their clinical, imaging, and electroencephalogram data were analyzed.ResultsA total of 18 patients were enrolled, including 15 males and 3 females. The clinical symptoms were convulsions, poor feeding, growth retardation, disorder of consciousness, developmental delay, hypotonia, and blood system changes. There were 6 cases (33%) of hydrocephalus, 9 (50%) of extracerebral space widened, 5 (27%) of corpus callosum thinning, 3 (17%) of ventricular dilation, 3 (17%) of abnormal signals in the brain parenchyma (frontal lobe, basal ganglia region, and brain stem), and 3 (17%) of abnormal signals in the lateral paraventricular. In addition, there were 3 cases (17%) of cerebral white matter atrophy and 1 (5%) of cytotoxic edema in the basal ganglia and cerebral peduncle. EEG data displayed 2 cases (11%) of hypsarrhythmia, 3 (17%) of voltage reduction, 12(67%) of abnormal discharge, 13 (72%) of abnormal sleep physiological waves or abnormal sleep structure, 1 (5%) of immature (delayed) EEG development, and 8 (44%) of slow background. There were 2 cases (11%) of spasms, 1 (5%) of atonic seizures, and 1 (5%) of myoclonic seizures. There were 16 patients (89%) with hyperhomocysteinemia. During follow-up, 1 patient was lost to follow-up, and 1 died. In total, 87.5% (14/16) of the children had varying developmental delays. EEG was re-examined in 11 cases, of which 8 were normal, and 3 were abnormal. Treatments included intramuscular injections of vitamin B12, L-carnitine, betaine, folic acid, and oral antiepileptic therapy. Acute treatment included anti-infective, blood transfusion, fluid replacement, and correcting acidosis. The other treatments included low-protein diets and special formula milk powder.ConclusionMethylmalonic acidemia can affect the central nervous system, leading to structural changes or abnormal signals on brain MRI. Metabolic screening and genetic testing help clarify the diagnosis. EEG can reflect changes in brain waves during the acute phase.

Cobalamin C Deficiency, an Inborn Error of Metabolism presenting with Subacute Neuropsychiatric Symptoms (P9-4.001)

<h3>Objective:</h3> Inpatient Neurology teams are often consulted to rule out neurological causes for new-onset neuropsychiatric symptoms. This case highlights the importance of considering possible Inborn Errors of Metabolism (IEM) that require specific treatments, and avoiding premature closure on a primary psychiatric disorder. <h3>Background:</h3> A 15-year-old presented to a pediatric hospital with a 4–8 week onset of neuropsychiatric (psychosis, psychomotor slowing, catatonia, sleep cycle irregularities, and tremors) and systemic (acute on chronic kidney injury and hypertension) symptoms. Neurology was consulted for further evaluation. In addition to the abnormal higher mental function exam, the neurological exam was significant for hyperreflexia in both the upper and lower extremities. <h3>Design/Methods:</h3> N/A <h3>Results:</h3> Neuroimaging (an initial non-contrast CT Head and MRI brain with and without contrast) did not reveal an intracranial abnormality. Analysis of cerebrospinal fluid, including an autoimmune encephalitis panel, was unremarkable. Metabolic testing was significant for elevated homocysteine and methylmalonic aciduria with normal Vitamin B12 levels. Genetics and metabolic consult recommended testing for Cobalamin C deficiency that returned positive with pathogenic mutations in MMACHC gene. Neuropsychiatric symptoms began to improve after the initiation of treatment with hydroxocobalamin, carnitine, betaine, and leucovorin. <h3>Conclusions:</h3> Cobalamin C deficiency (CblC) most commonly presents in infants less than 1 year, but is also known to present rarely in adolescence or adulthood, most commonly with subacute onset psychiatric symptoms, myelopathy, and cardiovascular disease. CblC is an autosomal recessive disorder caused most commonly by pathogenic variants within the MMACHC gene. Late-onset forms of IEM can present with isolated neuropsychiatric symptoms years after birth and thus are prone to be missed. Treatable metabolic disorders should be considered in the workup for new-onset neuropsychiatric symptoms. <b>Disclosure:</b> Dr. Engel has nothing to disclose. Dr. Rashid has nothing to disclose. Dr. Al-Beshri has nothing to disclose. Dr. Ananth has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Reata Therapeutics. The institution of Dr. Ananth has received research support from Acadia Pharmaceuticals.

Prenatal Diagnosis of Two Common Inborn Errors of Metabolism by Genetic and Mass Spectrometric Analysis of Amniotic Fluid.

Methylmalonic acidaemia (MMA) and ornithine transcarbamylase deficiency (OTCD) are both intoxication-type inborn errors of metabolism (IEM). Presently, genetic testing is the primary method for prenatally diagnosing these diseases. However, some reports have demonstrated that mass spectrometry approaches can prenatally diagnose some forms of inborn errors of metabolism using amniotic fluid. Therefore, in this study, genetic and mass spectrometry approaches were used for prenatally diagnosing MMA and OTCD. We collected amniotic fluid samples from 19 foetuses referred, 15 cases were referred for MMA and 4 for OTCD. Of the 15 MMA cases, seven were affected, as determined by genetic testing and the metabolite levels; the characteristic metabolites propionylcarnitine (C3), C3/acetylcarnitine (C2) ratio, methylmalonic acid and methylcitrate levels were significantly higher than the reference range. Eight foetuses were unaffected, and the C3, C3/C2 ratio, methylmalonic acid and methylcitrate levels were within the reference range. The C3, C3/C2, methylmalonic acid, and methylcitrate levels in the amniotic fluid significantly differed between the affected and unaffected foetuses (P = 0.0014, P = 0.0014, P = 0.0003, P = 0.0014, respectively). Moreover, the homocysteine level increased in the amniotic fluid of affected foetuses with MMACHC gene mutations. Of the four OTCD cases, genetic testing confirmed that two foetuses were affected and two were unaffected. However, the characteristic metabolite levels were within the reference range for all foetuses, including citrulline, orotic acid, and uracil. The genetic testing results were confirmed to be correct through the abortion tissue of the foetus and the postnatal follow-up. Our results suggest that mass spectrometry approaches are convenient method for improving the prenatal diagnosis of MMA. The characteristic metabolites C3, C3/C2, methylmalonic acid, and methylcitrate levels in amniotic fluid were reliable biochemical markers for the prenatal diagnosis of MMA.

Noninvasive Prenatal Testing of Methylmalonic Acidemia cblC Type Using the cSMART Assay for MMACHC Gene Mutations.

Noninvasive prenatal testing (NIPT) for monogenic disorders has been developed in recent years; however, there are still significant technical and analytical challenges for clinical use. The clinical feasibility of NIPT for methylmalonic acidemia cblC type (cblC type MMA) was investigated using our circulating single-molecule amplification and re-sequencing technology (cSMART). Trios molecular diagnosis was performed in 29 cblC type MMA-affected children and their parents by traditional Sanger sequencing. In the second pregnancy, invasive prenatal diagnosis (IPD) of the pathogenic MMACHC gene was used to determine fetal genotypes, and NIPT was performed using a novel MMACHC gene–specific cSMART assay. Maternal–fetal genotypes were deduced based on the mutation ratio in maternal plasma DNA. Concordance of fetal genotypes between IPD and NIPT, and the sensitivity and specificity of NIPT were determined. After removing two cases with a low P value or reads, the concordance ratio for NIPT and IPD was 100.00% (27/27), and the sensitivity and specificity were 100.00% (54.07–100.00%) and 100.00% (83.89–100.00%), respectively. This study demonstrates that NIPT using the cSMART assay for cblC type MMA was accurate in detecting fetal genotypes. cSMART has a potential clinical application as a prenatal diagnosis and screening tool for carrier and low-risk genotypes of cblC type MMA and other monogenic diseases.

Rapid screening of MMACHC gene mutations by high-resolution melting curve analysis.

BackgroundCobalamin (cbl) C is a treatable rare hereditary disorder of cbl metabolism with autosomal recessive inheritance. It is the most common organic acidemia, manifested as methylmalonic academia combined with homocysteinemia. Early screening and diagnosis are important. The mutation spectrum of the MMACHC gene causing cblC varies among populations. The mutation spectrum in Chinese population is notably different from that in other populations.MethodsA PCR followed by high‐resolution melting curve analysis (PCR‐HRM) method covering all coding exons of MMACHC gene was designed to verify 14 pathogenic MMACHC gene variants found in patients with cblC, including all common mutations in Chinese patients with cblC.ResultBy PCR‐HRM analysis, 14 pathogenic variants of MMACHC showed distinctly different melting curves, which were consistent with Sanger sequencing. The homozygous type of the most common mutation c.609G > A (p.Trp203Ter) can also be analyzed by specially designed PCR‐HRM.ConclusionThe established PCR‐HRM method for screening common pathogenic MMACHC variants in Chinese patients with cblC has the advantages of high accuracy, high throughput, low cost, and high speed. It is suitable for the large‐sample screening of suspected children with methylmalonic acidemia and carriers in population.

Treatable cause of hereditary spastic paraplegia: eight cases of combined homocysteinaemia with methylmalonic aciduria.

Combined homocysteinemia with methylmalonic aciduria (MMA/HCY) are genetic disorders of intracellular cobalamin (cbl) transport and processing that cause downstream deficiencies in methylcobalamin and adenosylcobalamin. Untreated disease is characterized biochemically by methylmalonic aciduria and hyperhomocysteinemia, while the clinical features are variable. When spastic paraplegia (SP) dominates, it is difficult to differentiate from hereditary spastic paraplegia (HSP). Clinical, biochemical and imaging features were reviewed in eight patients with MMA/HCY that mimicked HSP. Seven males and one female were enrolled. The median onset age was 13years old (range 7-26years old). The median time delay of diagnosis was 20.5months (range 2-60months). Spastic gait was the first symptom in four patients, while the other four patients presented with chronic emotional abnormalities or cognitive impairment. The main clinical manifestation was SP, and other neurological symptoms included cognitive impairment (5/8), spastic dysuria (3/8), personality change and depression (3/8), ataxia (2/8), seizures (2/8), limb numbness (2/8), and developmental delay (2/8). When patients were diagnosed, the mean serum homocysteine level, the methylmalonic acid level in urine, the serum propionylcarnitine (C3) level and the ratios of C3-to-acetylcarnitine (C2) and free carnitine (C0) were all dramatically elevated. Cranial MRIs showed nothing remarkable except mild brain atrophy. All spinal MRIs were normal except for case 8. Definite compound heterozygous mutations in MMACHC were detected in five cases. Follow-up indicated partial improvement in all the patients after intramuscular cbl, oral betaine and folate, supporting the diagnosis of MMA/HCY. Our data highlight the need for extensive investigation of intracellular cbl transport and processing, when spastic paraparesis is a prominent component of the clinical picture. Testing for urine methylmalonic acid and serum homocysteine levels is a simple but critical approach in suspected cases. Genetic testing, especially for MMACHC gene mutations, is needed. Raising awareness of this disorder could result in the timely initiation of targeted treatment, which may significantly improve patient outcomes.

Atteintes rénales au cours du déficit en cobalamine C

Cobalamin C deficiency (cblC) is the most common inborn error of vitamin B12 metabolism. This autosomal recessive disease is due to mutations in MMACHC gene, encoding a cyanocobalamin decyanase. It leads to hyperhomocysteinemia associated with hypomethioninemia and methylmalonic aciduria. Two distinct phenotypes have been described : early-onset forms occur before the age of one year and are characterized by a severe multisystem disease associating failure to thrive to neurological and ophthalmological manifestations. They are opposed to late-onset forms, less severe and heterogeneous. CblC deficiency-associated kidney lesions remain poorly defined. Thirty-eight cases have been described. Age at initial presentation varied from a few days to 28 years. Most of the patients presented renal thrombotic microangiopathy (TMA) associated with acute renal failure, and 21 patients presented typical lesions of renal thrombotic microangiopathy on kidney biopsy. Prognosis was poor, leading to death in the absence of treatment, and related to the severity of renal lesions in the early-onset forms. Late-onset disease had better prognosis and most of patients were weaned off dialysis after treatment initiation. We suggest that all the patients with renal TMA be screened for cobalamin metabolism disorder, regardless of age and even in the absence of neurological symptoms, to rapidly initiate the appropriate treatment.

MMACHC gene mutation in familial hypogonadism with neurological symptoms

Recent studies have convincingly documented that hypogonadism is a component of various hereditary disorders and is often recognized as an important clinical feature in combination with various neurological symptoms, yet, the causative genes in a few related families are still unknown. High-throughput sequencing has become an efficient method to identify causative genes in related complex hereditary disorders. In this study, we performed exome sequencing in a family presenting hypergonadotropic hypogonadism with neurological presentations of mental retardation, epilepsy, ataxia, and leukodystrophy. After bioinformatic analysis and Sanger sequencing validation, we identified compound heterozygous mutations: c.482G>A (p.R161Q) and c.609G>A (p.W203X) in MMACHC gene in this pedigree. MMACHC was previously confirmed to be responsible for methylmalonic aciduria (MMA) combined with homocystinuria, cblC type (cblC disease), a hereditary vitamin B12 metabolic disorder. Biochemical and gas chromatography-mass spectrometry (GC-MS) examinations in this pedigree further supported the cblC disease diagnosis. These results indicated that hypergonadotropic hypogonadism may be a novel clinical manifestation of cblC disease, but more reports on additional patients are needed to support this hypothesis.

Clinical and molecular analysis of cobalamin C type methylmalonic aciduria with homocystinuria in a Chinese family

Background Researches determined that c.365A＞T and c.658_66 0delAAG variant is rare type of MMACHC gene mutation in the patients with cobalamin C (CblC) type methylmalonic aciduria and homocystinuria (cblC disease).What is more,the cblC disease family with the same mutation has not been reported up to now.Objective This study was to detect and analyze the mutations in MMACHC gene in a Chinese family with cblC disease.Methods This protocol complied with Helsinki declaration,and all the medical examination were performed under the informed consent of custodian.The Chinese family was composed of four members of the two generations,including a 14-year male proband,his 4-year sister,their mother and father.All members of the family underwent complete ophthalmologic examinations covered with the ocular anterior segment and posterior segment.The peripheral blood as collected for the families for the extraction of DNA.All exons of MMACHC gene were screened for sequence alterations by PCR and direct DNA sequencing.Results The cblC disease family was verified to be anautosomal recessive inheritance.The proband and his sister appeared to be the cblC disease children and their parents were phenotypic normal.The sickened children were diagnosed and managed at 10 years old and 1 year old,respectively.No obvious abnormal finding was seen in the anterior ocular segment,but different degrees of macular atrophies were seen in both eyes of the children.In addition,nystagmus was found in the proband.The compound heterozygote mutations in the MMACHC gene were identified in two affected children,which included a deletion mutation (c.658_660delAAG,p.KdelLys) in exon 4 and a missense mutation (c.365A＞T,p.H122L) in exon 3,both of them were respectively inherited from their unaffected parents.However,c.365A＞T variant was sequenced in the phenotypica normal mother,and c.658_660delAAG variant was found in the phenotypica normal father.Conclusions A rare compound heterozygote mutation of MMACHC is identified in this Chinese family,indicating MMACHC may play a critical role in the development of cblC disease. Key words: Homocystinuria/genetics; Methylmalonic acid/metabolism; Heterozygote; DNA mutational analysis; Complication; Eye; cblC disease; Chinese

A clinical and gene analysis of late-onset combined methylmalonic aciduria and homocystinuria, cblC type, in China

BackgroundCombined methylmalonic aciduria and homocystinuria, cblC type (cblC disease), is the most common inborn disorder of cobalamin metabolism. This disorder is caused by MMACHC gene mutations, and it is usually diagnosed in the early neonatal period. Late-onset cblC is rare and difficult to recognize due to a wide diversity of symptoms. MethodsThree cases with late-onset combined methylmalonic aciduria and homocystinuria, cblC type, are reported; patients' clinical presentation, imaging and MMACHC gene mutations were analyzed. ResultsThe age of onset in the three patients was 22years, 40years and 7years of age. Two of the patients had MMACHC gene mutations heterozygous for c.609G>A and c.482G>A (case 1 and case 3). The other patient (case 2) presented with gene mutations heterozygous for c.609G>A and c.1A>G. The three patients presented with a heterogeneous clinical picture, including cognitive impairment, epilepsy, ataxia, pyramidal and peripheral nerve symptoms. Cerebral atrophy and bilateral hyperintensity in the deep white matter were visible in MRI scans of the patients' brains; those were significant findings in the three patients with late-onset cblC disease. In contrast with previous reports, bilateral cerebellar cortex abnormalities were also found in one patient (case 2). ConclusionAlthough its occurrence is rare, late-onset combined methylmalonic aciduria and homocystinuria, cblC type, should be considered in making a differential diagnosis in patients who present with neurological symptoms that are not consistent with common neurological diseases, especially when cognition, the pyramidal tract and peripheral nerves are involved.

CD46-associated atypical hemolytic uremic syndrome with uncommon course caused by cblC deficiency

CD46-associated atypical hemolytic uremic syndrome with uncommon course caused by cblC deficiency

Mutation analysis of the MMACHC gene in a pedigree with methylmalonic aciduria

To identify the mutation of the methylmalonic aciduria (cobalamin deficiency) CblC type, with homocystinuria (MMACHC) gene in a pedigree with methylmalonic aciduria. The MMACHC gene mutation was detected using polymerase chain reaction (PCR) and DNA sequencing. The MMACHC gene of 50 healthy people was also sequenced as control. A new mutation of 146_154 del CCTTCCTGG was found in the patient and his father, and was absent in the controls. A new mutation (146_154 del CCTTCCTGG) in the MMACHC gene was detected in a Chinese family with methylmalonic aciduria.