To investigate the clinical and gene detection characteristics of children with pyruvate kinase deficiency (PKD).

A PKD boy with chief complaint of " anemia for 2⁺ months" who was admitted to Chengdu Women′s and Children′s Central Hospital on 7 April 2016, was chosen as research object. The clinical data of PKD child were analyzed retrospectively, including the hospitalization situation of this admission, diagnosis process and follow-up. In the case of informed consent, peripheral blood samples were collected from PKD boy and his parents to screening gene mutations of them through disease related gene target sequence capture and second-generation sequencing technology. Then these gene mutations were verified by method of Sanger sequencing. With key words of " pyruvate kinase" and " hemolytic anemia" in Chinese, and " hemolytic anemia" " gene sequencing" in English etc., the literature of PKD with gene detection results were collected from relevant domestic and foreign databases from construction to January 2019, then reviewed the relevant data. The study was in line with World Medical Association Declaration of Helsinki revised in 2013.

①The child was admitted to hospital at age of 2⁺ months and up to now he was age of 2 years and 11 months, and had been followed up for more than 2 years. The main clinical manifestations of him were as follows: he appeared serious jaundice shortly after birth, results of blood routine examinations showed severe anemia, reticulocyte proportion increased obviously for many times, and it was suggested that hemolytic anemia should be diagnosed. His relative laboratory test results excluded glucose-6-phosphate dehydrogenase (G6PD) deficiency, Thalassemia anemia and other types of hemolytic anemia related diseases. Because treatment of " autoimmune hemolytic anemia" by glucocorticoid was not effective, the child was considered PKD. However, the test result of pyruvate kinase (PK) activity was normal. ②The results of gene tests: pyruvate kinase liver and RBC (PKLR) gene of his father was c. 1437-1G>A mutation in exon 10, and PKLR gene of his mother was c. 848T>C mutation in exon 6, respectively. Both sites and types mutations of PKLR gene from his parents were detected in the child. Both genetic abnormalities in the child and his father were not reported in Online Mendelian Inheritance in Man yet. According to clinical manifestations, laboratory examinations and genetic testing results, diagnosis of PKD of this child was confirmed. ③The PKD related literature search results showed that due to diverse clinical manifestations of PKD and PK activity was affected by many factors, a few cases of PKD had already been reported. A total of 12 PKD patients (included this child) with gene test results in China were reported, and all of them were PKLR gene mutation. Among 12 PKD patients, the heterozygous mutation was 83.3% (10/12), proportion of normal PK activity was 75.0% (9/12), proportion of blood transfusion dependence was 58.3% (7/12), 58.3% (7/12) of patients had hepatomegaly and (or) splenomegaly and 25.0% (3/12) of patients had cholelithiasis.

Some PKD patients with normal PK activity could be diagnosed by gene test.