title: A case of mucolipidosis II presenting with prenatal skeletal dysplasia and severe secondary hyperparathyroidism at birth.
abstract: Mucolipidosis II (ML II) or inclusion cell disease (I-cell disease) is a rarely occurring autosomal recessive lysosomal enzyme-targeting disease. This disease is usually found to occur in individuals aged between 6 and 12 months, with a clinical phenotype resembling that of Hurler syndrome and radiological findings resembling those of dysostosis multiplex. However, we encountered a rare case of an infant with ML II who presented with prenatal skeletal dysplasia and typical clinical features of severe secondary hyperparathyroidism at birth. A female infant was born at 37(+1) weeks of gestation with a birth weight of 1,690 g (<3rd percentile). Prenatal ultrasonographic findings revealed intrauterine growth retardation and skeletal dysplasia. At birth, the patient had characteristic features of ML II, and skeletal radiographs revealed dysostosis multiplex, similar to rickets. In addition, the patient had high levels of alkaline phosphatase and parathyroid hormone, consistent with severe secondary neonatal hyperparathyroidism. The activities of β-D-hexosaminidase and α-N-acetylglucosaminidase were moderately decreased in the leukocytes but were 5- to 10-fold higher in the plasma. Examination of a placental biopsy specimen showed foamy vacuolar changes in trophoblasts and syncytiotrophoblasts. The diagnosis of ML II was confirmed via GNPTAB genetic testing, which revealed compound heterozygosity of c.3091C>T (p.Arg1031X) and c.3456_3459dupCAAC (p.Ile1154GlnfsX3), the latter being a novel mutation. The infant was treated with vitamin D supplements but expired because of asphyxia at the age of 2 months.
authors.affiliation: Department of Pediatrics, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Ju Sun
authors.initials: JS
authors.lastname: Heo
authors.forename: Ka Young
authors.initials: KY
authors.lastname: Choi
authors.forename: Se Hyoung
authors.initials: SH
authors.lastname: Sohn
authors.forename: Curie
authors.initials: C
authors.lastname: Kim
authors.forename: Yoon Joo
authors.initials: YJ
authors.lastname: Kim
authors.forename: Seung Han
authors.initials: SH
authors.lastname: Shin
authors.forename: Jae Myung
authors.initials: JM
authors.lastname: Lee
authors.forename: Juyoung
authors.initials: J
authors.lastname: Lee
authors.forename: Jin A
authors.initials: JA
authors.lastname: Sohn
authors.forename: Byung Chan
authors.initials: BC
authors.lastname: Lim
authors.forename: Jin A
authors.initials: JA
authors.lastname: Lee
authors.forename: Chang Won
authors.initials: CW
authors.lastname: Choi
authors.forename: Ee-Kyung
authors.initials: EK
authors.lastname: Kim
authors.forename: Han-Suk
authors.initials: HS
authors.lastname: Kim
authors.forename: Beyong Il
authors.initials: BI
authors.lastname: Kim
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Choi