This paper analyzes the pathogenesis, clinical characteristics, treatment measures and prognosis of a case of methemoglobin and hemolytic anemia caused by acute nitrogen trifluoride poisoning. The patient with occupational exposure to nitrogen trifluoride was treated immediately after the onset of illness, methemoglobin was monitored and a comprehensive examination was conducted. After comprehensive analysis, it was considered that acute nitrogen trifluoride poisoning could cause methemoglobinemia, hemolytic anemia and liver injury. The patient was disengaged and given symptomatic treatment such as oxygen therapy, methylene blue, low-dose methylpredrone, vitamin C and reduced glutathione. The prognosis of the patient is good, which provides a reference for the clinical treatment and occupational health examination of nitrogen trifluoride poisoning.
本文对1例急性三氟化氮中毒致高铁血红蛋白血症、溶血性贫血患者的发病过程、临床特点、治疗措施及预后进行分析。患者职业暴露三氟化氮，发病后立即就诊，监测高铁血红蛋白并进行全面检查，综合分析后考虑急性三氟化氮中毒致高铁血红蛋白血症、溶血性贫血及肝损伤。脱离接触，给予氧疗、亚甲蓝、小剂量甲泼尼龙、维生素C、还原性谷胱甘肽等对症治疗，患者预后较好，为三氟化氮中毒的临床救治及职业健康检查提供参考。.

Recessive congenital methemoglobinemia (RCM) is a hereditary autosomal disorder with an extremely low incidence rate. Here, we report a case of methemoglobinemia type I in a patient with congenital persistent cyanosis. The condition was attributed to a novel compound heterozygous mutation in CYB5R3, characterized by elevated methemoglobin levels (13.4 % of total hemoglobin) and undetectable NADH cytochrome b5 reductase (CYB5R3) activity. Whole-exome sequencing (WES) revealed two heterozygous mutations in CYB5R3: a previously reported pathogenic missense mutation c.611G>A(p.Cys204Tyr) inherited from the father, and a novel stop codon mutation c.906A>G(p.*302Trpext*42) from the mother, the latter mutation assessed as likely pathogenic according to ACMG guidelines. In cells overexpressing the CYB5R3 c.906A>G mutant construct, the CYB5R3 mRNA level was significantly lower than in cells overexpressing the wild-type (WT) CYB5R3 construct. However, there was no significant difference in protein expression levels between the mutant and WT constructs. Notably, an additional protein band of approximately 55 kDa was detected in the mutant cells. Immunofluorescence localization showed that, compared to wild-type CYB5R3, the subcellular localization of the CYB5R3 p.*302Trpext*42 mutant protein did not show significant changes and remained distributed in the endoplasmic reticulum and mitochondria. However, the c.906A>G(p.*302Trpext*42) mutation resulted in increased intracellular reactive oxygen species (ROS) levels and decreased NAD+/NADH ratio, suggesting impaired CYB5R3 function and implicating this novel mutation as likely pathogenic.

BACKGROUND: The common cause of sodium nitrite poisoning has shifted from previous accidental intoxication by exposure or ingestion of contaminated water and food to recent alarming intentional intoxication as an employed method of suicide/exit. The subsequent formation of methemoglobin (MetHb) restricts oxygen transport and utilization in the body, resulting in functional hypoxia at the tissue level. In clinical practice, a mismatch of cyanotic appearance and oxygen partial pressure usually contributes to the identification of methemoglobinemia. Prompt recognition of characteristic mismatch and accurate diagnosis of sodium nitrite poisoning are prerequisites for the implementation of standardized systemic interventions.
METHODS: A pregnant woman was admitted to the Department of Critical Care Medicine at the First Affiliated Hospital of Harbin Medical University due to consciousness disorders and drowsiness 2 h before admission. Subsequently, she developed vomiting and cyanotic skin. The woman underwent orotracheal intubation, invasive mechanical ventilation (IMV), and correction of internal environment disturbance in the ICU. Her premature infant was born with a higher-than-normal MetHb level of 3.3%, and received detoxification with methylene blue and vitamin C, supplemental vitamin K1, an infusion of fresh frozen plasma, as well as respiratory support via orotracheal intubation and IMV. On day 3 after admission, the puerpera regained consciousness, evacuated the IMV, and resumed enteral nutrition. She was then transferred to the maternity ward 24 h later. On day 7 after admission, the woman recovered and was discharged without any sequelae.
CONCLUSIONS: MetHb can cross through the placental barrier. Level of MetHb both reflects severity of the sodium nitrite poisoning and serves as feedback on therapeutic effectiveness.

Hemoglobin M (Hb M) is a group of abnormal Hb variants that form methemoglobin, which leads to cyanosis. Patients with Hb M appear cyanotic but are usually asymptomatic. Cyanosis with low peripheral oxygen saturation is unresponsive to oxygen therapy despite normal partial pressure of oxygen. As such, close attention should be paid during anesthesia. We report the first case of a Hb M patient undergoing laparoscopic uterine myomectomy under general anesthesia.

Hemoglobin (Hb) Chile [β28(B10) Leu > Met; HBB: c.85 C > A] is a rare hemoglobin variant caused by a missense mutation in the HBB gene. Only one case of Hb Chile has been reported worldwide so far. It is an unstable hemoglobin, characterized by cyanosis associated with chronic methemoglobinemia and hemolytic anemia induced by sulfonamides or methylene blue.
A 9-year-3-month-old girl had mild anemia of unknown etiology for more than 6 years. She had a slight pallor without other symptoms or signs. The complete blood count revealed normocytic normochromic anemia with a sometimes-elevated reticulocyte count, and the bone marrow cytology showed marked erythroid hyperplasia, but the tests related to hemolysis were normal. Therefore, the whole exome sequencing was performed and showed a heterozygous mutation for HBB: c.85 C > A. With asymptomatic methemoglobinemia confirmed later, she was eventually diagnosed with Hb Chile.
This is the first report of Hb Chile in China and the second worldwide. This case shows that Hb Chile is clinically heterogeneous and difficult to diagnose and expands our understanding on the clinical and hematological traits of the disease.

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BACKGROUND: Congenital methemoglobinemia is a rare cyanosis cause that can be manifested in affected individuals. We report a case of congenital methemoglobinemia after middle ear cholesteatoma resection under general anesthesia.
METHODS: The primary concern of the patient is to safely perform cholesteatoma resection of the middle ear to reduce the pain associated with years of surgery and to survive the perioperative period.
METHODS: Congenital methemoglobinemia type 1.
METHODS: The patient underwent general anesthesia and cholesteatoma resection of the middle ear.
RESULTS: The patient successfully underwent cholesteatoma resection in the middle ear under general anesthesia and went through the perioperative period smoothly, and successfully returned to society.
CONCLUSIONS: For patients requiring general anesthesia complicated with rare methemoglobinemia, we improve the awareness of crisis and make comprehensive preparation and monitoring, learn the pathophysiological mechanism related to the disease, so as to protect the operation of methemoglobin patients under general anesthesia.

Nitrobenzene poisoning is uncommon, with most cases occurring in the dye, paint, and other chemical industries. Nitrobenzene enters the body mainly through the skin, respiratory tract, and oral cavity. Nitrobenzene poisoning symptoms include hypermethemoglobinemia, hemolytic anemia, liver and kidney dysfunction, cardiogenic pulmonary edema, and toxic encephalopathy, which endanger people\'s lives. Therefore, we present a case of nitrobenzene poisoning caused by skin absorption, focusing on its clinical characteristics and treatment outcomes. A 58 years-old man presented to our department with confusion and cyanosis. He has a history of hypertension and cerebral infarction. The patient was diagnosed with moderate occupational acute benzene poisoning with nitro compounds. Symptomatic support, methylene blue, and other antioxidant treatments were commenced after diagnosis. After treatment, the patient\'s condition gradually improved, and he was discharged.

Background and Objective: Mutations in the CYB5R3 gene cause reduced NADH-dependent cytochrome b5 reductase enzyme function and consequently lead to recessive congenital methemoglobinemia (RCM). RCM exists as RCM type I (RCM1) and RCM type II (RCM2). RCM1 leads to higher methemoglobin levels causing only cyanosis, while in RCM2, neurological complications are also present along with cyanosis. Materials and Methods: In the current study, a consanguineous Pakistani family with three individuals showing clinical manifestations of cyanosis, chest pain radiating to the left arm, dyspnea, orthopnea, and hemoptysis was studied. Following clinical assessment, a search for the causative gene was performed using whole exome sequencing (WES) and Sanger sequencing. Various variant effect prediction tools and ACMG criteria were applied to interpret the pathogenicity of the prioritized variants. Molecular dynamic simulation studies of wild and mutant systems were performed to determine the stability of the mutant CYB5R3 protein. Results: Data analysis of WES revealed a novel homozygous missense variant NM_001171660.2: c.670A > T: NP_001165131.1: p.(Ile224Phe) in exon 8 of the CYB5R3 gene located on chromosome 22q13.2. Sanger sequencing validated the segregation of the identified variant with the disease phenotype within the family. Bioinformatics prediction tools and ACMG guidelines predicted the identified variant p.(Ile224Phe) as disease-causing and likely pathogenic, respectively. Molecular dynamics study revealed that the variant p.(Ile224Phe) in the CYB5R3 resides in the NADH domain of the protein, the aberrant function of which is detrimental. Conclusions: The present study expanded the variant spectrum of the CYB5R3 gene. This will facilitate genetic counselling of the same and other similar families carrying mutations in the CYB5R3 gene.

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