The authors describe a seven months and a half little girl, A.B., affected by multiple localization osteomyelitis caused by an Atypical Mycobacterium, with the culture identifies as M. Avium, belonging to the third group of Runjon classification. The radiographic tests show a primary pulmonary complex and some osteolytic areas of the seventh right rib and of the bones of the lower legs (femur and tibia). From the beginning a multiple antituberculous chemotherapy against non tuberculous mycobacterial disease has initiated: Streptomycin (for two months) associated with Rifampicin, Isoniazid and Pyridoxine. The patient responds very slowly to the treatment and only three years later the whole radiologic regression of the lesions occurs. The interest of the case comes from the extreme rarity of disseminated bone localization during an atypical mycobacterial infection, and also from the early beginning of the clinical and radiologic manifestations.
Abstract Background: The expansion of newborn screening programs has increased the number of newborns diagnosed with inborn errors of metabolism in the presymptomatic phase, but it has also increased the number of costly, stress-producing false-positive results. Because propionylcarnitine (C3) is one of the analytes most frequently responsible for false-positive results, we aimed to develop a rapid liquid chromatography–tandem mass spectrometry (LC-MS/MS) method to identify free methylmalonic (MMA) and 3-OH propionic (3OH-PA) acids in blood spots. Methods: We studied newborn screening spots from 250 healthy controls; 124 from infants with abnormal C3, of whom only 5 (4%) were truly affected; 124 from infants with altered isolated methylmalonylcarnitine; and 4 from clinically diagnosed patients. Whole blood was eluted from a 3.2-mm dried blood spot by a CH3CN/H2O 7:3 and 5 mL/L formic. This extract was injected into a LC-MS/MS equipped with pneumatically assisted electrospray without derivatization. Total analysis time was 5 min per sample. Results: The assays were linear up to 3300 nmol/L for both metabolites. Intra- and interassay imprecision data were 3.6%–8% and 3.1%–6%, respectively, for MMA and 5.2%–20% and 3.6%–17% for 3OH-PA. Limit of detection and limit of quantitation were 1.95 and 4.2 μmol/L, respectively, for MMA and 8 and 10 μmol/L for 3OH-PA. The recoveries were 92.9%–106.1%. No deterioration was noted on the columns after 500 chromatographic runs. If the new method had been used as a 2nd-tier test for the 124 samples, only the 5 true positives would have been recalled for additional samples, and the positive predictive value would have been 100%. Conclusions: This method has the potential to markedly reduce false-positive results and the associated costs and anxiety. It may also be suitable for diagnosing and routinely monitoring blood spots for methylmalonic aciduria and propionic acidemia.
Summary Malonic aciduria is a rare autosomal recessive disorder caused by deficiency of malonyl‐CoA decarboxylase, encoded by the MLYCD gene. We report on a patient with clinical presentation in the neonatal period. Metabolic investigations led to a diagnosis of malonyl‐CoA decarboxylase deficiency, confirmed by decreased activity in cultured fibroblasts. High doses of carnitine and a diet low in lipids led to a reduction in malonic acid excretion, and to an improvement in his clinical conditions, but at the age of 4 months he died suddenly and unexpectedly. No autopsy was performed. Molecular analysis of the MLYCD gene performed on the proband's RNA and genomic DNA identified a previously undescribed mutation (c.772–775delACTG) which was homozygous. This mutation was present in his mother but not in his father; paternity was confirmed by microsatellite analysis. A hypothesis of maternal uniparental disomy (UPD) was investigated using fourteen microsatellite markers on chromosome 16, and the results confirmed maternal UPD. Maternal isodisomy of the 16q24 region led to homozygosity for the MLYCD mutant allele, causing the patient's disease. These findings are relevant for genetic counselling of couples with a previously affected child, since the recurrence risk in future pregnancies is dramatically reduced by the finding of UPD. In addition, since the patient had none of the clinical manifestations previously associated with maternal UPD 16, this case provides no support for the existence of maternally imprinted genes on chromosome 16 with a major effect on phenotype.
