Diagnosis and clinical phenotype analysis of a case with large fragment homozygous deletion of rare β gene cluster

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To report on a case with homozygous deletion of large β gene cluster and its clinical characteristics. A total of 71 001 peripheral blood samples were subjected to capillary electrophoresis and conventional testing for common thalassemia mutations. The genotypes of suspected β gene cluster deletions were analyzed by Gap-PCR and multiplex ligation-dependent probe amplification (MLPA). Their hematological characteristics were compared by statistical analysis R software. Eighty-nine cases were detected with Chinese Gγ(Aγδβ) 0-deletion of the β gene cluster, which gave a detection rate of 0.13%. Among these, there were 70 Chinese Gγ(Aγδβ) 0-deletion heterozygotes and 18 Chinese Gγ(Aγδβ) 0-deletion heterozygotes in conjunct with α thalassemia. There were 13 683 samples with normal findings. A significant difference was detected in 6 groups of hematological parameters between the heterozygous carriers (P<0.05) by box plotting. One case of Chinese Gγ(Aγδβ) 0-deletion homozygote was discovered for the first time. The clinical phenotype was mild anemia. Hemoglobin electrophoresis showed that the value of HbF was 100%. The carrier rate for large fragment deletions of β gene cluster in Huizhou region is rather high, for which the value of HbF is significantly increased. Attention should be paid to screening and diagnosis of rare genotype to prevent missed diagnosis and/or misdiagnosis.