RESUMO
Objective To analyze 4 child patients with 3-methylcrotonyl-coenzyme A carboxylase deficiency (MCCD) identified by neonatal screening and confirmed by urine gas chromatography-mass spectrometry (GC/MS) and genetic analysis.Methods Newborns whose C4DC + CSOH concentration was above 0.6 μmol/L in newborn screening were recalled for rescreening,and the CADC + C5OH concentrations in their mothers were detected.The child patients suspected with MCCD were further confirmed by urine GC/MS and genetic analysis.Results Three child patients were definitely diagnosed as MCCD by genetic analysis,including 1 MCCD,1 maternal MCCD and 1 paternal MCCD.The other 1 child patient suspected with MCCD had only one allele in MCCC1.Conclusion The mother and father of newborns with elevated C4DC + C5OH identified in neonatal screening should routinely perform MS / MS testing.When only one pathogenic locus is found in the suspected MCCD child patients by genetic analysis,they should be followed up regularly.
RESUMO
La deficiencia aislada de 3-metilcrotonil-CoA carboxilasa es un desorden autosómico recesivo del catabolismo de leucina con gran variabilidad fenotípica. Es uno de los errores innatos del metabolismo más común, con una incidencia de hasta 1:36.000 neonatos. Mujeres que presentan esta condición han sido identificadas únicamente luego de que las muestras de tamizaje neonatal de sus hijos sanos presentaran resultados anormales. La deficiencia de 3-metilcrotonil-CoA carboxilasa materna debe tomarse en cuenta al evaluar un resultado positivo de 3-OH-isovalerilcarnitina en tamizaje neonatal. Además, se debe valorar si es necesario brindar seguimiento clínico periódico a los niños diagnosticados con déficit de 3-metilcrotonil-CoA carboxilasa en Costa Rica, pues está documentado que la mayoría de estos pacientes permanecen asintomáticos.
Isolated 3-methylcrotonyl-coenzymeA carboxylase deficiency is an autosomal recessive disorder of leucine catabolism with considerable phenotypic heterogeneity. It is one of the most common inborn errors of metabolism with an incidence as high as 1 in 36.000 newborns. Women presenting this deficiency have been identified only by detection of abnormal results in newborn screening samples of their healthy babies. Maternal 3-methylcrotonyl-coenzyme A carboxylase deficiency should be taken into account when assessing a positive newborn screening result for 3-hydroxy-isovaleryl carnitine. The question of whether or not to provide periodic medical examination to children diagnosed with 3-methylcrotonyl-coenzymeA carboxylase deficiency in Costa Rica should also be addressed, since there are clinical studies sustaining that most of these patients remain asymptomatic.