Spondylometaphyseal dysplasia with cerebral hypomyelination (SMD‐H) is a very rare but distinctive phenotype, unusually combining spondylometaphyseal dysplasia with hypomyelinating leukodystrophy. Recently, SMD‐H has been associated with variants confined to a specific intra‐genic locus involving Exon 7, suggesting that AIFM1 plays an important role in bone development and metabolism as well as cerebral myelination. Here we describe two further affected boys, one with a novel intronic variant associated with skipping of Exon 7 of AIFM1 and the other a synonymous variant within Exon 7 of AIFM1. We describe their clinical course and radiological and genetic findings, providing further insight into the natural history of this condition.

中文翻译：

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AIFM1 相关的 X 连锁脊椎干骺端发育不良伴脑髓鞘形成不足

脊椎干骺端发育不良伴脑髓鞘形成不良（SMD-H）是一种非常罕见但独特的表型，罕见地将脊椎干骺端发育不良与髓鞘形成性脑白质营养不良相结合。最近，SMD-H 与仅限于涉及外显子 7 的特定基因内位点的变异相关，表明AIFM1在骨骼发育和代谢以及脑髓鞘形成中起着重要作用。在这里，我们描述了两个进一步受影响的男孩，一个具有与跳过AIFM1外显子 7 相关的新型内含子变异，另一个是AIFM1外显子 7 内的同义变异。我们描述了他们的临床病程以及放射学和遗传学发现，从而进一步了解这种疾病的自然病程。