4H leukodystrophy, also known as Pol III‐related leukodystrophy, is a rare autosomal recessive neurodegenerative disorder characterized by hypomyelination, hypodontia, and hypogonadotropic hypogonadism. It is caused by biallelic mutations in POLR3A , POL3RB , or POLR1C . So far, only two patients have been described with homozygosity for the common c.1568T>A (p.Val523Glu) POLR3B mutation, both of them showing a remarkably mild clinical course. Here, we report another patient with homozygosity for the same mutation, but with a more severe phenotype including ataxia, developmental delay, and intellectual disability. This information is of importance for clinicians to provide comprehensive counseling to patients with 4H leukodystrophy and their families.

中文翻译：

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纯合子POLR3B突变引起的4H白细胞营养不良：表型的进一步描述。

4H白细胞营养不良，也称为与Pol III相关的白细胞营养不良，是一种罕见的常染色体隐性遗传性神经退行性疾病，其特征为髓鞘过少，牙髓过少和性腺功能低下性腺功能减退。它是由POLR3A，POL3RB或POLR1C中的双等位基因突变引起的。迄今为止，仅2名患者被描述为普通c.1568T> A（p.Val523Glu）POLR3B具有纯合性突变，它们都显示出非常温和的临床过程。在这里，我们报道了另一名具有相同突变纯合性但具有更严重表型的患者，包括共济失调，发育迟缓和智力残疾。此信息对于临床医生为4H白细胞营养不良患者及其家人提供全面的咨询非常重要。