{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nRecent studies have revealed that the human protein encoded by the HDHD1 gene, also referred to herein as PUDP, functions as a highly specific pseudouridine 5′-phosphatase. This enzyme catalyzes the dephosphorylation of pseudouridine 5′-phosphate—a modified nucleotide produced during RNA degradation—thereby facilitating the conversion of this intermediate into pseudouridine, which is subsequently excreted intact in urine. Notably, the enzyme exhibits a very low Km (~0.3 µM) and a kcat of 1.6 s⁻¹ for its substrate, showing at least a 1000-fold higher catalytic efficiency compared to other phosphate esters. Its requirement for Mg²⁺ and sensitivity to inhibitors such as Ca²⁺ and vanadate, along with its small molecular mass (~26 kDa), place it within the haloacid dehalogenase family of phosphatases."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn a clinical context, targeted genetic analyses in patients with X‐linked ichthyosis (XLI) have identified deletions in the Xp22 region that encompass not only the steroid sulfatase (STS) gene but also the PUDP gene. The detection of such contiguous gene deletions underscores the importance of PUDP in human biology and suggests that its loss may occur alongside STS, potentially contributing to or modifying the phenotype of XLI."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Alice Preumont, Rim Rzem, Didier Vertommen, et al. "}, {"type": "b", "children": [{"type": "t", "text": "HDHD1, which is often deleted in X-linked ichthyosis, encodes a pseudouridine-5'-phosphatase."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Biochem J (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1042/BJ20100174"}], "href": "https://doi.org/10.1042/BJ20100174"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20722631"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20722631"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Joonhong Park, Yong Gon Cho, Jin Kyu Kim, et al. "}, {"type": "b", "children": [{"type": "a", "children": [{"type": "t", "text": "i"}], "href": "i"}, {"type": "t", "text": "STS"}, {"type": "a", "children": [{"type": "t", "text": "/i"}], "href": "/i"}, {"type": "t", "text": " and "}, {"type": "a", "children": [{"type": "t", "text": "i"}], "href": "i"}, {"type": "t", "text": "PUDP"}, {"type": "a", "children": [{"type": "t", "text": "/i"}], "href": "/i"}, {"type": "t", "text": " Deletion Identified by Targeted Panel Sequencing with CNV Analysis in X-Linked Ichthyosis: A Case Report and Literature Review."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Genes (Basel) (2023)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.3390/genes14101925"}], "href": "https://doi.org/10.3390/genes14101925"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "37895274"}], "href": "https://pubmed.ncbi.nlm.nih.gov/37895274"}]}]}]}