UNASSIGNED: Routine metabolic assessments for methylmalonic acidemia (MMA), propionic acidemia (PA), and homocysteinemia involve detecting metabolites in dried blood spots (DBS) and analyzing specific biomarkers in serum and urine. This study aimed to establish a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous detection of three specific biomarkers (methylmalonic acid, methylcitric acid, and homocysteine) in DBS, as well as to appraise the applicability of these three DBS metabolites in monitoring patients with MMA, PA, and homocysteinemia during follow-up.
UNASSIGNED: A total of 140 healthy controls and 228 participants were enrolled, including 205 patients with MMA, 17 patients with PA, and 6 patients with homocysteinemia. Clinical data and DBS samples were collected during follow-up visits.
UNASSIGNED: The reference ranges (25th-95th percentile) for DBS methylmalonic acid, methylcitric acid, and homocysteine were estimated as 0.04-1.02 μmol/L, 0.02-0.27 μmol/L and 1.05-8.22 μmol/L, respectively. Following treatment, some patients achieved normal metabolite concentrations, but the majority still exhibited characteristic biochemical patterns. The concentrations of methylmalonic acid, methylcitric acid, and homocysteine in DBS showed positive correlations with urine methylmalonic acid (r = 0.849, p < 0.001), urine methylcitric acid (r = 0.693, p < 0.001), and serum homocysteine (r = 0.721, p < 0.001) concentrations, respectively. Additionally, higher levels of DBS methylmalonic acid and methylcitric acid may be associated with increased cumulative complication scores.
UNASSIGNED: The LC-MS/MS method established in this study reliably detects methylmalonic acid, methylcitric acid, and homocysteine in DBS. These three DBS metabolites can be valuable for monitoring patients with MMA, PA, and homocysteinemia during follow-up. Further investigation is required to determine the significance of these DBS biomarkers in assessing disease burden over time.

UNASSIGNED: Methylmalonic acidemia (MMA) with hyperhomocysteinemia is caused by cobalamin deficiency, mainly due to disturbance of cobalamin C (cblC) metabolism. Its clinical manifestations involve many organs. However, cases of coronary artery ectasia have been rarely reported.
UNASSIGNED: Here, we report the case of a 4-year-old girl who was hospitalized mainly because of pallor, brown urine, and fatigue, followed by hypertension, renal insufficiency, hemolytic anemia, cardiac enlargement, cardiac insufficiency, and coronary artery ectasia. Thrombotic microangiopathy (TMA) was confirmed by renal pathological examination. Metabolic examination showed hyperhomocysteinemia and methylmalonic aciduria. Furthermore, genetic assessment confirmed MMACHC gene variant, which confirmed the final diagnosis of a cblC defect. Intramuscular injection of hydroxy-cobalamin, oral medications of betaine, levocarnitine, folic acid, and aspirin were administered. Three months later, the patient\'s condition was significantly improved. Anemia was corrected, and the renal function was normal. Heart size, cardiac function, and coronary artery structure completely returned to normal.
UNASSIGNED: The clinical manifestation of cblC deficiency is atypical. This critical condition may be associated with multiple organ involvement. A rare complication, coronary artery ectasia, can also occur. Early identification, careful evaluation, and appropriate treatment are crucially important for the improvement of this disease prognosis.

Methylmalonic Aciduria and Homocystinemia, cobalamin C (cblC) is an inherited disease of vitamin B12 metabolism with a wide spectrum of clinical manifestations. cblC presenting with pulmonary hypertension (PH) as leading sympotom is rare and easily misdiagnosed because of limited awareness. Timely diagnosis is crucial by the relentless progression without appropriate treatment.
We reported a 12-year-old girl with a 3-year history of progressively reduced activity tolerance and a 3-month history of orthopnea. Metabolic testing revealed increased levels of plasma homocysteine and urine methylmalonic acid. cblC deficiency was subsequently confirmed by genetic testing. The patient was treated with hydroxocobalamin, betaine, folinic acid and levocarnitine for cblC disease. Sildenafil, bosentan, spironolactone and hydrochlorothiazide was administrated for PH and right heart failure. At 3-month follow-up, she had an apparent resolution of dyspnea and cyanosis. Metabolic abnormalities resolved the decrease of plasma homocysteine and urine methylmalonic acid. A right heart catheterization showed a reduced pulmonary pressure.
This case emphasizes the importance of an early diagnosis and initiation of treatment for cblC deficiency. Unexplained PH in children and young adults should prompt metabolic screening for the differential diagnosis.

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