Pyruvate kinase deficiency (PKD) is an autosomal recessive condition, caused due to homozygous or compound heterozygous mutation in the PKLR gene resulting in non-spherocytic
hereditary hemolytic anemia. Clinical manifestations in PKD patients vary from moderate to severe lifelong
hemolytic anemia either requiring neonatal exchange transfusion or
blood transfusion support. Measuring PK
enzyme activity is the gold standard approach for diagnosis but residual activity must be related to the increased reticulocyte count. The confirmatory diagnosis is provided by PKLR gene sequencing by conventional as well as targeted next-generation sequencing involving genes associated with enzymopathies, membranopathies,
hemoglobinopathies, and
bone marrow failure disorders. In this study, we report the mutational landscape of 45 unrelated
PK deficiency cases from India. The genetic sequencing of PKLR revealed 40 variants comprising 34 Missense Mutations (MM), 2
Nonsense Mutations (NM), 1 Splice site, 1 Intronic, 1 Insertion, and 1 Large Base Deletion. The 17 novel variants identified in this study are A115E, R116P, A423G, K313I, E315G, E318K, L327P, M377L, A423E, R449G, H507Q, E538K, G563S, c.507 + 1 G > C, c.801_802 ins A (p.Asp268ArgfsTer48), IVS9dsA-T + 3, and one large base deletion. In combination with previous reports on
PK deficiency, we suggest c.880G > A, c.943G > A, c.994G > A, c.1456C > T, c.1529G > A are the most frequently observed mutations in India. This study expands the phenotypic and molecular spectrum of PKLR gene disorders and also emphasizes the importance of combining both targeted next-generation sequencing with bioinformatics analysis and detailed clinical evaluation to elaborate a more accurate diagnosis and correct diagnosis for transfusion dependant
hemolytic anemia in a cohort of the Indian population.