The novel compound heterozygous variants identified in a Chinese family with glucose phosphate isomerase deficiency and pathogenicity analysis.

BACKGROUND AND AIMS: Glucose phosphate isomerase (GPI) deficiency is an extremely rare autosomal recessive disorder caused by mutations in the GPI gene. In this research, the proband displaying typical manifestations of haemolytic anaemia and his family members were recruited to analyse the pathogenicity of the detected variants. METHODS: Peripheral blood samples were collected from the family members and genomic DNA was extracted and targeted for capture and sequencing. The effect of the candidate pathogenic variants on splicing was further investigated using the minigene splicing system. The computer simulation was also used for further analysis of the detected data. RESULTS: The proband carried the compound heterozygous variants c.633 + 3 A > G and c.295G > T in the GPI gene, which have never been reported before. In the genealogy, co-segregation of the mutant genotype with the phenotype was established. The minigene study showed that intronic mutations resulted in abnormal pre-mRNA splicing. Specifically, the two aberrant transcripts: r.546_633del and r.633 + 1_633 + 2insGT were transcribed by the minigene plasmid expressing the c.633 + 3 A > G variant. The missense mutation c.295G > T in exon 3 resulted in altering glycine at codon 87 to cysteine which was predicted to be pathogenic in an in silico analysis. Deeper analyses revealed that the Gly87Cys missense mutation led to steric hindrance. Compared to the wild-type, the mutation G87C led to a significant increase in intermolecular forces. CONCLUSION: Overall, the novel compound heterozygous variants in the GPI gene contributed to the etiology of the disease. Genetic testing can assist in the diagnosis. The novel gene variants identified in the present study has further expanded the mutational spectrum of GPI deficiency, which can better guide family counselling.

Case report: Glucose 6-phosphate-isomerase deficiency combine with avascular necrosis of bilateral femoral head.

Background: Glucose 6-phosphate-isomerase deficiency (GPI) is an uncommon autosomal recessive genetic disorder characterized by chronic asphoric hemolytic anemia, jaundice, and hepatospleenomegaly of varying degrees. Avascular necrosis of the femoral head in children may be caused by Legg-calve-perthes disease or hematological diseases. However, to date, there is no literature reporting on femoral head avascular necrosis as a complication of GPI. Case presentation: Herein we report a 6-year-old child admitted with no pain and abnormal gait in both lower extremities for 3 years, the patient received a genetic inspection and radiology test. Full-exon detection and Sanger sequencing verification were performed on the children and their parents C. 553T>A homozygous missense mutation (NM_ 001289790, F 185 I) was found in exon 6 of the GPI gene, which was inherited from parents. The radiology test showed avascular necrosis of the bilateral femoral head. The patient received traction and wore a spica splint every night and non-weight bearing hip joint rehabilitation every day for 12 months, after which, the gait of the femoral head of this patient improved significantly, and follow up radiation results showed the area of avascular necrosis of the femoral head had decreased. Conclusion: Careful investigation of GPI children with abnormal gait is recommended to avoid misdiagnosis, GPI combined with avascular necrosis of the femoral head should be considered as a differential diagnosis in GPI children with abnormal gait.

Clinical, laboratory, and mutational profile of children with glucose phosphate isomerase deficiency: a single centre report.

Glucose phosphate isomerase (GPI) deficiency is an autosomal recessive condition with mutations in the GPI gene on chromosome 19q13.1. Patients present with congenital non-spherocytic hemolytic anemia, and occasionally intellectual disability. In this study, we describe the clinical, hematological and biochemical parameters in the largest single-center cohort consisting of 17 GPI-deficient cases. Demographic and clinical data were noted, and red cell enzyme activity levels were estimated. Mutation analysis was done by single-stranded-conformation polymorphism, restriction-fragment length polymorphism and Sanger's sequencing of exon 12 of the GPI gene. The male-to-female ratio was 0.7:1, median age at diagnosis was 5.0 years, 82.3% of patients had severe neonatal jaundice, and 13.3% had subtle neurological manifestations. Median Hb and MCV levels were 6.3 g/dl and 130.2 fl. Splenectomized patients required fewer transfusions. Sixteen of 17 patients had the pathogenic c.1040G > A (p.Arg347His) homozygous mutation in exon12 of the GPI gene, and one had the pathogenic c.1414C > T(p.Arg472Cys) homozygous mutation in exon 16. In summary, we report that neonatal jaundice, macrocytosis and high prevalence of p.Arg347His variant were predominant in GPI deficiency with prominent lack of neurological manifestations, and we emphasize the benefits of splenectomy and the need for genetic counseling.

A Case Report of Congenital Non-spherocytic Hemolytic Anemia in a Patient from India.

Congenital non-spherocytic hemolytic anemia (CNSHA) is a rare autosomal recessive condition that presents as a congenital hemolytic anemia. The absence of vital enzymes required for glycolysis such as homozygous glucose phosphate isomerase (GPI) and red blood cell (RBC) nucleotide metabolism predisposes the RBCs to hemolysis. No spherocytosis is seen on peripheral smear as well as no signs of immune-mediated destruction of RBCs. We present a rare case of a previously healthy 21-year-old female patient with CNSHA from India.

Next-generation sequencing unravels homozygous mutation in glucose-6-phosphate isomerase, GPIc.1040G>A (p.Arg347His) causing hemolysis in an Indian infant.

INTRODUCTION: Inherited anemias diagnostic workup requires a step-wise algorithm. Causal genes implicated in congenital hemolytic anemia are numerous, making a gene-by-gene approach by Sanger sequencing time consuming, expensive and labour intensive. Targeted resequencing can be of great use in explaining these cases. METHODOLOGY: Six months female presented with neonatal jaundice and negative family history. Clinical and laboratory evidences were suggestive of hemolytic anemia. G6PD deficiency, thalassemias, hemoglobinopathies, autoimmune hemolytic anemia, hereditary spherocytosis and pyruvate kinase deficiency were excluded. Targeted resequencing on Illumina MiSeq using TruSight One sequencing panel was performed to identify the causative mutations. RESULTS: 35-40% of RBCs were acanthocytes and echinocytes. A missense homozygous mutation was found inglucose-6-phosphate isomerase, GPI [c.1040G>A (p.Arg347His), rs137853583] which results in nonspherocytic hemolytic anemia. CONCLUSION: This study describes GPI p.Arg347His mutation for the first time from India and is the first report of red cell GPI deficiency diagnosed using NGS-based resequencing and highlights the potential of this technique in clinical practice.