A novel deletion/insertion caused by a replication error in the β-globin gene locus control region

Hemoglobin. 2011;35(4):316-22. doi: 10.3109/03630269.2011.571331.

Abstract

Deletions in the β-globin locus control region (β-LCR) lead to (εγδβ)(0)-thalassemia [(εγδβ)(0)-thal]. In patients suffering from these rare deletions, a normal hemoglobin (Hb), phenotype is found, contrasting with a hematological thalassemic phenotype. Multiplex-ligation probe amplification (MLPA) is an efficient tool to detect β-LCR deletions combined with long-range polymerase chain reaction (PCR) and DNA sequencing to pinpoint deletion breakpoints. We present here a novel 11,155 bp β-LCR deletion found in a French Caucasian patient which removes DNase I hypersensitive site 2 (HS2) to HS4 of the β-LCR. Interestingly, a 197 bp insertion of two inverted sequences issued from the HS2-HS3 inter-region is present and suggests a complex rearrangement during replication. Carriers of this type of thalassemia can be misdiagnosed as an α-thal trait. Consequently, a complete α- and β-globin gene cluster analysis is required to prevent a potentially damaging misdiagnosis in genetic counselling.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Base Sequence
  • DNA Replication / genetics
  • Humans
  • Locus Control Region / genetics
  • Male
  • Molecular Sequence Data
  • Mutagenesis, Insertional*
  • Nucleic Acid Amplification Techniques / methods
  • Sequence Deletion*
  • beta-Globins / genetics*
  • beta-Thalassemia / diagnosis
  • beta-Thalassemia / genetics

Substances

  • beta-Globins