X-linked hypomyelination with spondylometaphyseal dysplasia (H-SMD) associated with mutations in AIFM1

Noriko Miyake, Nicole I. Wolf*, Ferdy K. Cayami, Joanna Crawford, Annette Bley, Dorothy Bulas, Alex Conant, Stephen J. Bent, Karen W. Gripp, Andreas Hahn, Sean Humphray, Shihoko Kimura-Ohba, Zoya Kingsbury, Bryan R. Lajoie, Dennis Lal, Dimitra Micha, Amy Pizzino, Richard J. Sinke, Deborah Sival, Irene Stolte-DijkstraAndrea Superti-Furga, Nicole Ulrick, Ryan J. Taft, Tsutomu Ogata, Keiichi Ozono, Naomichi Matsumoto, Bernd A. Neubauer, Cas Simons, Adeline Vanderver

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

An X-linked condition characterized by the combination of hypomyelinating leukodystrophy and spondylometaphyseal dysplasia (H-SMD) has been observed in only four families, with linkage to Xq25-27, and recent genetic characterization in two families with a common AIFM1 mutation. In our study, 12 patients (6 families) with H-SMD were identified and underwent comprehensive assessment accompanied by whole-exome sequencing (WES). Pedigree analysis in all families was consistent with X-linked recessive inheritance. Presentation typically occurred between 12 and 36 months. In addition to the two disease-defining features of spondylometaphyseal dysplasia and hypomyelination on MRI, common clinical signs and symptoms included motor deterioration, spasticity, tremor, ataxia, dysarthria, cognitive defects, pulmonary hypertension, nystagmus, and vision loss due to retinopathy. The course of the disease was slowly progressive. All patients had maternally inherited or de novo mutations in or near exon 7 of AIFM1, within a region of 70 bp, including synonymous and intronic changes. AIFM1 mutations have previously been associated with neurologic presentations as varied as intellectual disability, hearing loss, neuropathy, and striatal necrosis, while AIFM1 mutations in this small region present with a distinct phenotype implicating bone. Analysis of cell lines derived from four patients identified significant reductions in AIFM1 mRNA and protein levels in osteoblasts. We hypothesize that AIFM1 functions in bone metabolism and myelination and is responsible for the unique phenotype in this condition.

Original languageEnglish
Pages (from-to)185-194
Number of pages10
JournalNeurogenetics
Volume18
Issue number4
DOIs
Publication statusPublished - 1 Dec 2017

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