Coinheritance of alpha-thalassemia-1 and hemoglobin E/beta zero-thalassemia: practical implications for neonatal screening and genetic counseling

A Formula to Identify Potential Cases of β-Thalassemia/HbE Disease Among Patients With Absent HbA, HbE >75% and HbF Between 5 and 15

OBJECTIVE

To establish a simple formula to be used for discrimination between β-thalassemia/hemoglobin E (β-thal/HbE) and homozygous hemoglobin (Hb)E in specimens with absent hemoglobin (Hb)A, HbE of greater than 75%, and HbF between 5% and 15%.

METHODS

We analyzed laboratory results from February 2015 through February 2018. Molecular analysis for diagnosis of β-thal mutation and HbE was performed in specimens that contained HbE of greater than 75% and HbF from 5% to 15%, as measured by high-performance liquid chromatography (HPLC). HbA2 and HbF levels were also measured by capillary electrophoresis. Then, the formula (6 × HbA2 + HbF)/MCV was developed.

RESULTS

The score of 0.9 or higher was found in all 19 β-thal/HbE specimens (100%) and only 8 of 65 homozygous HbE specimens (12.3%). Also, the formula yielded 90.5% efficiency in identifying β-thal/HbE disease, and the efficiency was found to be higher compared with when the HbA2 value of greater than 6% was used by itself (85.4%).

CONCLUSION

The formula (6 × HbA2 + HbF)/MCV, with a cutoff point at 0.9, could identify the potential cases of β-thal/HbE disease among patients with absent HbA, HbE of greater than 75%, and HbF between 5% and 15%.

Problems in determining thalassemia carrier status in a program for prevention and control of severe thalassemia syndromes: a lesson from Thailand

BACKGROUND

Prevention and control of severe β thalassemia by carrier detection and identification of couples at risk in developed countries is one of the most successful stories in modern medicine. Similar programs in developing countries especially Southeast Asia, are more problematic because both α and β thalassemias are highly prevalent. In Thailand, there are limited data on whether we could determine, based on hematological phenotypes, the mutation severity and/or coinheritance of α thalassemia in β thalassemia traits.

METHODS

Comprehensive molecular, hematology and hemoglobin analyses of the α and β globin genes were performed in 141 healthy individuals identified as β thalassemia carriers.

RESULTS

Seventeen different β globin mutations were successfully identified out of all cases analyzed. Although the majority of the mutations identified were the β⁰ or severe β⁺ thalassemia alleles, a high proportion of mild mutations (25%) was observed. Of these β thalassemia traits, 22.3% were found to co-inherit the α thalassemias. Milder hematological phenotypes were noted in β⁺ compared with β⁰ thalassemia traits when the α globin genes were intact. Although co-inheritance of α⁰ thalassemia might be suspected in cases with skewed profiles, due to the overlapping values, it remains difficult to apply these parameters for reliable carrier determination.

CONCLUSIONS

A combination of hemoglobin analysis and DNA testing seems to be the best way to confirm carrier status in a region with high frequency for both α and β thalassemias. Underdiagnoses of carrier status could hamper the effectiveness of a thalassemia prevention and control program.

Clinico-haematological Profile of HbE Syndrome in Adults and Children

Haemoglobin E beta thalassemia (HbE beta thalassemia) has a remarkable variability in clinical expression ranging from a mild form of thalassemia intermedia to a transfusion dependent condition. An overlap between the mild variety of HbE beta thalassemia and homozygous HbE disease is common, however, differentiation is required for early institution of therapy and for predicting the later clinical course. Fifty cases of Hb E syndrome comprising of 43 cases of Hb E beta thalassemia and 7 cases of homozygous HbE disease were studied. Their clinico- haematological features and results of high performance liquid chromatography (HPLC) were analysed.

[A family survey of syndromes of traditional Chinese medicine in patients with beta-thalassemia]

OBJECTIVE

To explore the relationship between syndromes of traditional Chinese medicine (TCM) and genetic background in patients with beta-thalassemia.

METHODS

TCM syndromes were surveyed in the selected 78 patients with beta-thalassemia intermedia including 120 parents. The gene mutations were detected separately. The frequency and score of TCM syndromes between the offspring and their parents in different family types were analyzed, and the differences were compared.

RESULTS

The 73 families were divided into two family types by hereditary characteristics. Family type one meant that genotypes of one of the parents were normal, while the offspring genotypes were heterozygous and were exactly the same as another parent. In the 22 families of type one, the heterozygous offspring manifested 6 high-frequency symptoms and signs such as spontaneous perspiration, dry mouth and dry throat, pale or sallow complexion, tidal fever and night sweating, lassitude and pale fingernails. The heterozygous parents manifested 5 high-frequency symptoms and signs such as lassitude in loins and knees, dizziness, aversion to cold and cold limbs, tinnitus, dry mouth and dry throat. The normal parents manifested 3 high-frequency symptoms and signs such as lassitude in loins and knees, dizziness, and spontaneous perspiration. TCM syndrome score in the heterozygous offspring was higher than that in the heterozygous and normal parents, but there was no significant difference (P>0.05). Family type two meant that genotypes of both parents were heterozygous, while the offspring genotypes were heterogenic duplex heterozygotes. In the 51 families of type two, the offspring manifested 9 high-frequency symptoms and signs such as pale or sallow complexion, spontaneous perspiration, dry mouth and dry throat, pale fingernails, tidal fever and night sweating, lassitude, frequent attack of common cold, dysphoria with feverish sensation in chest, and yellow discoloration of the skin and sclera. The parents manifested 3 high-frequency symptoms and signs such as lassitude in loins and knees, dizziness, aversion to cold and cold limbs. TCM syndrome score in the offspring was significant higher than that in the parents (P<0.01).

CONCLUSION

In the two family types, TCM syndrome in the offspring is of yin-blood deficiency, while the syndrome of the parents is of kidney deficiency. The differences of TCM syndromes between the offspring and the parents may have some relations to the type of mutant genes and genetically modified ingredients. This research provides scientific evidence to TCM syndrome differentiation treatment of thalassemia.

Evaluation of alpha hemoglobin stabilizing protein (AHSP) as a genetic modifier in patients with β thalassemia

Although β thalassemia is considered to be a classic monogenic disease, it is clear that there is considerable clinical variability between patients who inherit identical β globin gene mutations, suggesting that there may be a variety of genetic determinants influencing different clinical phenotypes. It has been suggested that variations in the structure or amounts of a highly expressed red cell protein (alpha hemoglobin stabilizing protein [AHSP]), which can stabilize free α globin chains in vitro, could influence disease severity in patients with β thalassemia. To address this hypothesis, we studied 120 patients with Hb E-β thalassemia with mild, moderate, or severe clinical phenotypes. Using gene mapping, direct genomic sequencing, and extended haplotype analysis, we found no mutation or specific association between haplotypes of AHSP and disease severity in these patients, suggesting that AHSP is not a disease modifier in Hb E-β thalassemia. It remains to be seen if any association between AHSP and clinical severity is present in other population groups with a high frequency of β thalassemia. (Blood. 2004;103:3296-3299)

Unusual phenotype of hemoglobin EE with hemoglobin H disease: a pitfall in clinical diagnosis and genetic counseling

Two unrelated individuals previously diagnosed as hemoglobin (Hb) EE were found to be, in fact, Hb EE with Hb H disease. This globin genotype normally results as Hb EF Bart disease. This unusual genotype-phenotype interaction highlights the need for molecular analysis in affected individuals with Hb E disorders before appropriate genetic counseling and genetic risk estimation in offspring can be given.

Beta-thalassemia in association with a new delta-chain hemoglobin variant [delta116(g18)Arg-->Leu]: implications for carrier screening and prenatal diagnosis

We describe a complicated genetic counseling and prenatal diagnostic case involving an East Indian couple that had lost two consecutive pregnancies. Hemoglobinopathy screening was conducted to investigate the possibility of Hb Bart's hydrops fetalis or Hb H hydrops fetalis. The initial work-up indicated that alpha-thalassemia was not a contributing factor, with both parents being carriers of single gene deletions (-alpha(3.7)/alphaalpha). However, the Hb electrophoresis results indicated that the couple might be at risk for having children with Hb E/Hb Lepore disease. Subsequent DNA testing demonstrated that the father carried the Hb E mutation, but failed to confirm that the mother carries the Hb Lepore deletion. Sequence analysis revealed that the mother was heterozygous for a common East Indian beta(0)-thalassemia mutation, yet had a normal level of Hb A(2). The mother also carried a previously unreported missense mutation of the delta-globin gene, in cis with the beta(0)-thalassemia mutation, which gave rise to the minor Hb variant originally misidentified as Hb Lepore. This case illustrates the importance of comprehensive molecular analyses for accurate assessment of genetic risks for hemoglobinopathy syndromes.