Browsing by Author "Bartsakoulia, Marina (55364416700)"

Hereditary persistence of fetal hemoglobin (HPFH) is a rare hereditary condition resulting in elevated levels of fetal hemoglobin (HbF) in adults. Typical HPFH is associated with promoter mutations or large deletions affecting the human fetal globin (HBG1 and HBG2) genes, while genetic defects in other genes involved in human erythropoiesis, e.g. KLF1, also result in atypical HPFH. Here, we report the first KLF1 gene promoter mutation (KLF1:g.-148G > A) that is associated with increased HbF level. This mutation was shown to result in drastically reduced CAT reporter gene expression in K562 cells, compared to the wild-type sequence (p = 0.009) and also in reduced KLF1 gene expression in vivo. Furthermore, consistent with in silico analysis, electrophoretic mobility shift analysis showed that the KLF1:g.-148G > A mutation resides in a Sp1 binding site and further that this mutation leads to the ablation of Sp1 binding in vitro. These data suggest that the KLF1:g-148G > A mutation could play a role in increasing HbF levels in adults and further underlines the role of KLF1 as one of the key transcription factors involved in human fetal globin gene switching. © 2012 Springer-Verlag Berlin Heidelberg.

Using a combination of exome sequencing and linkage analysis, we investigated an English family with two affected siblings in their 40s with recessive Charcot-Marie Tooth disease type 2 (CMT2). Compound heterozygous mutations in the immunoglobulin-helicase-mbinding protein 2 (IGHMBP2) gene were identified. Further sequencing revealed a total of 11 CMT2 families with recessively inherited IGHMBP2 gene mutations. IGHMBP2 mutations usually lead to spinal muscular atrophy with respiratory distress type 1 (SMARD1), where most infants die before 1 year of age. The individuals with CMT2 described here, have slowly progressive weakness, wasting and sensory loss, with an axonal neuropathy typical of CMT2, but no significant respiratory compromise. Segregating IGHMBP2 mutations in CMT2 were mainly loss-of-function nonsense in the 50 region of the gene in combination with a truncating frameshift, missense, or homozygous frameshift mutations in the last exon. Mutations in CMT2 were predicted to be less aggressive as compared to those in SMARD1, and fibroblast and lymphoblast studies indicate that the IGHMBP2 protein levels are significantly higher in CMT2 than SMARD1, but lower than controls, suggesting that the clinical phenotype differences are related to the IGHMBP2 protein levels. © 2014 The Authors.

Using a combination of exome sequencing and linkage analysis, we investigated an English family with two affected siblings in their 40s with recessive Charcot-Marie Tooth disease type 2 (CMT2). Compound heterozygous mutations in the immunoglobulin-helicase-mbinding protein 2 (IGHMBP2) gene were identified. Further sequencing revealed a total of 11 CMT2 families with recessively inherited IGHMBP2 gene mutations. IGHMBP2 mutations usually lead to spinal muscular atrophy with respiratory distress type 1 (SMARD1), where most infants die before 1 year of age. The individuals with CMT2 described here, have slowly progressive weakness, wasting and sensory loss, with an axonal neuropathy typical of CMT2, but no significant respiratory compromise. Segregating IGHMBP2 mutations in CMT2 were mainly loss-of-function nonsense in the 50 region of the gene in combination with a truncating frameshift, missense, or homozygous frameshift mutations in the last exon. Mutations in CMT2 were predicted to be less aggressive as compared to those in SMARD1, and fibroblast and lymphoblast studies indicate that the IGHMBP2 protein levels are significantly higher in CMT2 than SMARD1, but lower than controls, suggesting that the clinical phenotype differences are related to the IGHMBP2 protein levels. © 2014 The Authors.