[Genetic testing and pedigree analysis for a case with intermediate α-thalassemia[--SEA/α90-92(AGCTTCGG)α]].

OBJECTIVE
To explore the genetic basis for a Chinese pedigree affected with a rare non-deletional hemoglobin H disease (Hb H disease).


METHODS
Peripheral venous blood samples of the proband and his parents were collected and subjected to routine blood testing, hemoglobin electrophoresis and screening for common mutations associated with thalassemia. Next generation sequencing was carried out to detect potential pathogenic variant, and candidate variant was verified by Sanger sequencing.


RESULTS
The proband was found to harbor a rare HbA2: c272_279delAGCTTCGG variant, which compounded with southeast Asian type deletion of α-thalassemia (--SEA). The two mutations were respectively inherited from his mother and father.


CONCLUSION
The rare HbA2: c.272_279delAGCTTCGG variant compounded with southeast Asian type α-thalassemia (--SEA) probably underlay the non-deletion Hb H in the proband. Above finding has enabled genetic counseling and prenatal diagnosis for this family.