Galactose is an essential carbohydrate for cellular metabolism, as it contributes to energy production and storage in several human tissues while also being a precursor for glycosylation. Galactosylated glycoconjugates, such as glycoproteins, keratan sulfate-containing proteoglycans and glycolipids, exert a plethora of biological functions, including structural support, cellular adhesion, intracellular signaling and many more. The biological relevance of galactose is further entailed by the number of pathogenic conditions consequent to defects in galactosylation and galactose homeostasis. The growing number of rare congenital disorders involving galactose along with its recent therapeutical applications are drawing increasing attention to galactose metabolism.

In this review, we aim to draw a comprehensive overview of the biological functions of galactose in human cells, including its metabolism and its role in glycosylation, and to provide a systematic description of all known congenital metabolic disorders resulting from alterations of its homeostasis.

半乳糖是细胞代谢必不可少的碳水化合物，因为它有助于多种人体组织中的能量产生和储存，同时也是糖基化的前体。半乳糖基化的糖缀合物，例如糖蛋白、含硫酸角质素的蛋白聚糖和糖脂，发挥着多种生物学功能，包括结构支持、细胞粘附、细胞内信号传导等。半乳糖基化和半乳糖稳态缺陷导致的致病条件的数量进一步导致了半乳糖的生物学相关性。越来越多的罕见先天性疾病涉及半乳糖及其最近的治疗应用，越来越多地关注半乳糖代谢。

在这篇综述中，我们旨在全面概述半乳糖在人体细胞中的生物学功能，包括其代谢及其在糖基化中的作用，并系统描述所有已知的由其体内平衡改变引起的先天性代谢紊乱。