The genetic basis of asymptomatic codon 8 frame-shift (HBB:c25_26delAA) β(0) -thalassaemia homozygotes

Molecular Basis and Genetic Modifiers of Thalassemia

Thalassemia syndromes are common monogenic disorders and represent a significant health issue worldwide. In this review, the authors elaborate on fundamental genetic knowledge about thalassemias, including the structure and location of globin genes, the production of hemoglobin during development, the molecular lesions causing α-, β-, and other thalassemia syndromes, the genotype-phenotype correlation, and the genetic modifiers of these conditions. In addition, they briefly discuss the molecular techniques applied for diagnosis and innovative cell and gene therapy strategies to cure these conditions.

Identification of novel mutations in β-thalassemia patients in Maysan Governorate, Iraq

BACKGROUND

In homozygous β-thalassemia, the primary genetic modifiers affecting the clinical severity of β-thalassemia are genetic variants and the ability to reduce globin chain imbalance, thus resulting in a milder form of thalassemia. However, there are few reports on the molecular genetics of β-thalassemia in Iraq.

METHODS

We performed PCR and DNA sequencing on 40 Iraqi patients who were clinically suspected of having β-thalassemia.

RESULTS

The first genetic sequencing study was conducted in Maysan Governate, Iraq, using patients from various locations to identify novel mutations. There were five novel mutations: 294.T>C 12% (city center and Almajar district), 205. C>T 25% (city center, Alsalam, and Almashrah districts), 289.G>A 38% (Almaymuna and Gleat Salih districts), 49.T>C 32% (city center), and 624.C>A 32% (city center). These mutations were identified among β-thalassemia patients by two regions of HBB gene 696 bp and 861 bp.

CONCLUSIONS

The discovery of new genetic variants helps predict the severity of β-thalassemia disease. There are relatively few studies in molecular genetics of β-thalassemia in Iraq, and the new mutations reported here will provide valuable data for the prevention and control of β-thalassemia in Maysan Governate, Iraq. The results can lead to new genetic sequencing investigations for other Iraqi regions.

A Mild Phenotype of Severe β+ Thalassemia in a 16-Month-Old Boy

β thalassemia is characterized by a deficient production of functional β-globin chains and a relative excess of α-globin chains. An extremely diverse clinical spectrum-asymptomatic to transfusion-dependent-is primarily due to homozygosity or compound heterozygosity for the very large number of β-thalassemia-causing mutations, along with interacting mutations that affect the α-globin and γ-globin genes and their expression. We report a case of a 16-month-old boy who was initially diagnosed with iron deficiency anemia until he was later found to be homozygous for a severe β-thalassemia genotype with a mild hematologic phenotype. This was likely as a result of his ability to produce high levels of fetal hemoglobin.