MRIで髄鞘化遅延所見を認めた7カ月男児の18番染色体長腕欠失症候群の1例

A case of 18q- syndrome in a 7-month-old boy with delayed myelination demonstrated on MRI

18番染色体長腕欠失症候群（以下，18q-症候群）は，Pelizaeus-Merzbacher病などと並んでMRIで髄鞘化遅延所見を呈する疾患として知られているが，1歳未満の画像所見の報告は少ない。今回我々は筋緊張低下を契機に発見され，MRIで髄鞘化遅延所見を認めた7カ月男児の18q-症候群の1例を経験したので，文献的考察とともに報告する。

A 7-month-old boy was noted to have hypotonia. On brain MRI, nearly all white matter was hyperintensity on T2-weightged images and hypointensity on T1-weighted images, suggesting delayed myelination. Follow-up MRI after 4 months showed almost the same imaging findings as the first examination. He was diagnosed with 18q- syndrome by FISH genetic testing. In 18q- syndrome, T1- weighted images typically shows slightly hyperintensity of the white matter. This finding, however, may not be obvious under 1 year of age.