3-Methylcrotonylglycinuria (3-MCCD)는 상염색체 열성 질환으로 3-methylcrotonyl-CoA carboxylase(3-MCC)의 결핍에 의해 발생한다. 최근 신생아시기에 대사이상질환 선별검사의 도입과 더불어 본 질환의 유병률이 증가하고 있다. 본 질환의 환자 대부분이 무증상이나 일부에서 신경학적 이상이 동반되어 유전상담에 어려움을 겪고 있다. 본 보고에서는 신생아 선별검사를 통하여 발견되어 3-MCCD로 진단되어 4세까지 정상 발달을 보이는 증례를 보고한다. 환자는 MCCC2 유전자에 p.[D280Y]+[D280Y] 돌연변이를 가지고 있다. 향후 국내의 3-MCCD 환자들의 임상양상과 유전학적 특성에 대한 고찰이 필요하다.

Enzyme replacement of therapy (ERT) is one of the most promising therapeutic strategies for the treatment of lysosomal storage disorders. ERT is available in three types of Mucopolysaccharidosis (MPS): for MPS I (Aludrazyme$^{(R)}$), MPS II (Elaprase$^{(R)}$) and MPS VI (Naglazyme$^{(R)}$) patients who are over 5 years old. But recently, early diagnosis can be done by expert clinicians and even in prenatal case. We describe the case of ERT under 5 years old MPS patients. Up to June, 2010 in Samsung Medical Center, there are 6patients who were diagnosed as MPS and started ERT under 5 years old. 3 patients were MPS I, 3 patients were MPS II. 2 patient who was diagnosed as MPS I was female and others were male. Their age at diagnosis were 4 to 37month-old (4, 13, 16, 25, 27, 37 month-old) and they are now 9 to 60 month-old (9, 39, 32, 81, 60 month-old). The youngest patient was started ERT at 4 month-old and others were started at their 13 to 49 month-old (13, 29, 27, 28, 49 month-old). First manifested symptoms of patients were macrocephaly, kyphosis and coarse face appearance. Especially, in 2 of them, one was MPS I and the other was MPS II had elder brother with same disease. And the youngest one was diagnosed by the iduronate-2-sulfatase (IDS) gene analysis from chorionic villi sampling. His mother knew that she was a heterozygous carrier of IDS gene mutation because her younger brother died from MPS II. All of them confirmed as MPS by the enzyme assay in leukocytes and fibroblast skin culture. We started ERT with ${\alpha}$-L-iduronidase(Aldurazyme$^{(R)}$) to MPS I and did recombinant human iduronate-2-sulfatase (Elaprase$^{(R)}$) to MPS II patients as recommended dose as over 5 years old. But for MPS II patient who was 4 month old, we started ERT by recombinant human IDS (Elaprase$^{(R)}$) with reduced dose 0.1 mg/kg and increased dose every 2 weeks by 0.1mg/kg up to 0.5mg/kg IV infusion. During ERT, all patients had no adverse effects and the excretion of GAGs were decreased. We have evaluated other clinical symptoms such as liver/ spleen volume, heart function and neurologic evaluation. We describe a successful ERT to MPS I and MPS II patient under 5 years old without any adverse event. It indicates that ERT in young children are well tolerated and that it has several effects which may confer clinical benefits with long-term therapy.