acute intermittent porphyria, mechanisms, aminolevulinic acid (ALA), attack Porphyrias are a group of inherited metabolic diseases that include eight types, each of which is caused by a mutation that affects an enzyme of the heme biosynthetic pathway. When an enzyme defect has physiological significance, it leads to overproduction of pathway precursors prior to the defective step. The partial absence of the third enzyme in the heme biosynthetic pathway, porphobilinogen deaminase (PBGD) also known as hydroxymethylbilane synthase (HMBS), results in acute intermittent porphyria (AIP), which affects mainly women. Subjects who had AIP symptoms were deemed to have manifest AIP (MAIP). Clinical manifestations are usually diverse and non-specific. Acute AIP episodes may present with abdominal pain, nausea, and vomiting, and repeated episodes may result in a series of chronic injuries. Therefore, studying the mechanisms of acute and chronic manifestations of AIP is of great significance. This review aims to summarize the possible mechanisms of acute and chronic manifestations in patients with AIP.

Background: Acute intermittent porphyria (AIP) is a rare inherited disorder with extremely low prevalence. Early detection of patients with potential pathogenic hydroxymethylbilane synthase (HMBS) variants is crucial for clinical prognosis. This study was designed to investigate the prevalence of pathogenic HMBS variants in Chinese population. Methods:The China Metabolic Analysis Project (ChinaMAP) database was employed to predict the prevalence of pathogenic HMBS variants in the Chinese population according to the variant interpretation guidelines of The American College of Medical Genetics and Genomics (ACMG). And the prevalence of pathogenic HMBS variants in Mixed American (AMR), African/African American (AFR), and Non-Finnish European (NFE) populations were estimated based on the Genome Aggregation Database (gnomAD) genome V3.0 database according to the guidelines of ACMG. An epidemiological investigation of AIP was conducted in Hebei Province, China through collecting the annual newly-diagnosed AIP cases of inpatients in 32 comprehensive grade III A hospitals from January 2011 to December 2020 in Hebei, China.Results: A total of 5 pathogenic/likely pathogenic (P/LP) HMBS variants were identified and the prevalence of pathogenic HMBS variants was predicted to be 1/1,765. Furthermore, based on the gnomAD genome V3.0 database, the estimated prevalence of pathogenic HMBS variants was 1/1,367, 1/1,403, and 1/621 in AMR, AFR, and NFE populations, respectively. The distribution of these variants varied among different racial populations. Moreover, AIP patients were predominantly hospitalized in comprehensive grade III A tertiary hospitals in Hebei province over a 10-year period. A total of 39 patients were newly-diagnosed with AIP, and a majority of them were female (n=36). The annual incidence between 2011 and 2017 {0.03 [95% confidence interval (CI): 0.01 to 0.11] to 0.05 (95% CI: 0.07 to 0.14) per million population} was generally lower than [0.07 (95% CI: 0.03 to 0.17) to 0.08 (95% CI: 0.03 to 0.18) per million] in 2018 and thereafter.Conclusions: China has made great strides in the management of AIP. More nationwide epidemiological surveys and study of the prevalence rate of AIP patients in China are urgently required.

acute intermittent porphyria, primary Sjogren's syndrome, autoimmune disease, treatment Acute intermittent porphyria (AIP) is a rare inherited metabolic disease associated with heme metabolism. Primary Sjogren's syndrome (PSS) is a common autoimmune disease. The combined presence of AIP and PSS complicates treatment. A rare case of concomitant AIP and PSS is reported in this paper. A 30-year-old woman with AIP had recurrent acute abdominal pain, nausea and vomiting, constipation, persistent chest, back, and waist pain, red urine, positivity for porphobilinogen (PBG) in urine and a pathogenic mutation of the HMBS gene. Two and a half years after she was diagnosed with AIP, she was diagnosed with PSS based on dryness of the eyes and mouth, the elevation of immunoglobulins (IgG and IgA) and positive results on an anti-SS-A antibody test, an anti-SS-B antibody test, Schirmer's test and a labial gland biopsy. A mutation in the HMBS gene was detected in the patient and her cousin, but the patient had more severe AIP and more severe symptoms (such as epilepsy and a limp), which may be related to the co-morbidity of PSS. According to her PSS activity score, the patient had an ESSDAI score of 9 and required systemic treatment. However, potential medications were limited by AIP, so mycophenolate mofetil was eventually added to delay the progression of the primary disease.