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BACKGROUND: Pathogenic POR variants cause P450 oxidoreductase deficiency, a rare steroidogenesis disorder. Missense changes are well characterized, but the clinical and molecular consequences of splicing defects remain unclear. METHODS: We identified a novel homozygous splice variant (c.1249-2A>C) in a patient with disorders of sex development and Antley-Bixler syndrome -like skeletal malformations. By reviewing 12 published cases and performing minigene assays on five variants (c.731 + 1G>A, c.732-2A>T, c.947 + 1G>A, c.948-30G>A, c.1249-2A>C), we characterized their splicing outcomes. Structural consequences were predicted using AlphaFold; nonsense-mediated mRNA degradation was assessed for c.1249-2A>C using cycloheximide block. RESULTS: c.731 + 1G>A and c.947 + 1G>A caused intron retention with premature termination, deleting FAD/NADPH-binding domains. c.732-2A>T and c.1249-2A>C skipped exons 8 and 12, which altered FAD-binding site conformation. c.1249-2A>C mRNA reduction was not rescued by cycloheximide, arguing against NMD and suggesting nuclear retention or intranuclear decay. We classified two variants as pathogenic (c.731 + 1G>A, c.947 + 1G>A), two as likely pathogenic (c.732-2A>T and the novel c.1249-2A>C), and one as likely benign (c.948-30G>A). CONCLUSION: Our findings establish that POR splicing variants, whether causing exon skipping or intron retention, disrupt essential domains and produce severe disease. Minigene-based functional testing enables precise variant classification and sharpens genotype-phenotype correlations, supporting improved diagnosis and informed genetic counseling.

BACKGROUND: Cytochrome P450 oxidoreductase deficiency (PORD) is an ultra-rare autosomal recessive disorder caused by mutations in the POR gene and characterized by highly heterogeneous skeletal, genital, and endocrine manifestations. Owing to this complexity, PORD remains frequently underrecognized in clinical practice, and integrated clinical-genetic syntheses remain limited. METHODS: A retrospective analysis was conducted on the clinical data of a PORD patient treated at Shenzhen Children's Hospital. Relevant literature was retrieved from PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI). Reported cases were analyzed with respect to sex, age, geographic distribution, clinical manifestations, and POR gene variants. RESULTS: The patient from our hospital, a 7-month-old infant, presented with characteristic features including frontal bossing, craniosynostosis, flat nasal bridge, proximal radioulnar synostosis, clitoromegaly, partial labial fusion, and steroid hormone abnormalities. Genetic testing identified compound heterozygous variants, p.G146fs*111, a novel mutation, and p.R457H. The patient underwent bilateral mandibular distraction osteogenesis and cranial reconstruction, which alleviated airway obstruction, swallowing difficulty, and craniosynostosis. A total of 50 eligible studies were identified, comprising 167 patients (male:female = 77:90). The major clinical findings were skeletal deformities in 124 cases (74.25%), gonadal deformities in 121 (72.46%), hormonal abnormalities or delayed puberty in 127 (76.05%), and adrenal insufficiency or crisis in 108 (64.67%). Additionally, ovarian cysts were observed in 36 female patients (40.00%). Among all patients, the allele frequency of the p.R457H variant was 27.25%, while that of the p.A287P variant was 14.97%. In the 22 Chinese patients, the allele frequency of the p.R457H variant reached 38.64%. CONCLUSION: We report the clinical features of a PORD patient carrying a novel POR mutation, p.G146fs*111. PORD typically presents with skeletal and genital malformations as well as adrenal insufficiency. Management requires multidisciplinary collaboration, including individualized steroid replacement, regular blood pressure monitoring, and surgical intervention when necessary. The p.R457H variant may represent a hotspot mutation in East Asian populations.

Humeroradial synostosis (HRS) is a rare congenital limb malformation, characterised by fusion of the humeral and radial bones, leading to functional disability of the elbow joint. HRS may be reported in familial or sporadic cases and observed either isolated or as part of a syndromic condition. According to an extensive review of the literature, a dozen known conditions may comprise an HRS. The present review aims to propose an updated classification based on molecular pathways (chondrogenesis and osteogenesis; limb development and patterning; genome regulation), combined with a concise overview of the conditions associated with HRS. This knowledge could guide molecular analyses, patient management and genetic counselling. As some cases remain unexplained, further genetic and epidemiological studies are required to evaluate the contribution of genetic and environmental factors in HRS physiopathology.

How do cells precisely coordinate sterol metabolism with survival and death signals in diverse physiological and pathological contexts? This fundamental question has gained increasing attention as accumulating evidence reveals that enzymes traditionally associated with lipid biosynthesis may have unexpected regulatory functions beyond metabolism. Cytochrome P450 family 51 subfamily A member 1 (CYP51A1), a conserved sterol 14α-demethylase essential for cholesterol synthesis, exemplifies this emerging concept. Although well-characterized as an antifungal drug target in microorganisms, the roles of human CYP51A1 in development, cell death regulation, and disease pathogenesis remain underexplored. Recent studies have uncovered that CYP51A1 not only contributes to cholesterol homeostasis but also modulates multiple forms of regulated cell death-including apoptosis, ferroptosis, alkaliptosis, and pyroptosis-via sterol intermediates or cholesterol-independent mechanisms. Moreover, dysregulation of CYP51A1 has been implicated in a wide spectrum of diseases, such as cancer, cataracts, Antley-Bixler syndrome, autoimmune disorders, metabolic liver disease and neurodegeneration. In this review, we provide a comprehensive synthesis of CYP51A1's structure, regulatory networks, and non-canonical functions. We propose a unifying framework in which CYP51A1 integrates metabolic reprogramming and cell fate control, highlighting its potential as a therapeutic target across diverse human diseases.

P450 oxidoreductase deficiency (PORD) affects cytochrome enzyme activities, causing various symptoms, such as adrenal insufficiency, disorders of sex development and skeletal malformations. This study aims to elucidate the clinical manifestations, genotype characteristics, diagnosis and management of 46,XX karyotype patients with PORD in China. A retrospective study included twelve 46,XX PORD patients in a Chinese tertiary medical center from 2004 to 2024. The patients' clinical characteristics were summarized based on manifestations, hormone profiles, and responses to treatments. The age of first visit was 7-31 years. Except for one young girl presenting with ambiguous genitalia since born, 11 patients presented with either abnormal menses or multiple ovarian cysts. Six patients showed masculinization of their external genitalia, and ten patients showed varying degrees of skeletal deformity. Progesterone was elevated and ovarian reserve was poor in all patients. The most frequent POR variant, c.1370G > A, located in exon 11 occurred in 11/12 patients with an allele frequency of 87.5% (21/24). Two novel nonsense mutations, c.1684dupG and c.2040dupC, were identified and assessed as pathogenic and likely pathogenic by ACMG, respectively. The c.1370G > A might be a dominant mutation type of POR in China. Female patients with PORD have a vulnerable ovarian reserve, and their ovarian macrocysts can be managed conservatively for fertility preservation. This study specifically focuses on PORD in 46,XX Chinese individuals, which implies its genetic causes with novel genetic findings and summarizes the puzzling spectrum of clinical manifestations.