Is genetic counseling important in hemoglobin H disease?
Abstract
Alpha thalassemia is a genetic disease characterized by insufficient expression or definite absence of the α-globin chain. Three large deletions (thal-1; 26.5 kb or MedII, 20.5 kb and 17.4 kb or MedI) and two small deletions (thal-2; 4.2 kb and 3.7 kb) have been characterized in our country. In addition, two different PolyA mutations (PA1: AATAAA>AATAAG and PA2: AATAAA>AATGA) on the α2-globin gene (αα/αPAα), 5nt deletion (αα/α5ntα), and unstable Hb variant (CD 59; GGC→GAC) synthesized by the α1-globin gene (αα/ααCD59) have been reported. More than ten different combinations of α-thal-1 and α-thal-2 (--/-α) or HbH genotypes with point mutations (--/αPAα or --/ααCD59) were determined. In this study, which was carried out in Çukurova region, it is aimed to emphasize the importance of giving genetic counseling to families with alpha thalassemia carriers and to determine genotype combinations. DNA was isolated from blood samples taken from 5 children and their families who were admitted to Çukurova University Balcalı Hospital and diagnosed with severe anemia (Hb <9, MCV <70) as a result of blood count HbA2 values were measured by HPLC. Gene deletions were determined by multiplex PCR. When two families with two children are compared, the fact that the second child of the family who receives genetic counseling service is a carrier and the second child of the family who does not receive genetic counseling service is patient highlights the importance of genetic counseling service.
Keywords
Kaynakça
- Çürük MA. HbH (β4) disease in çukurova. Southern turkey. Hemoglobin. 2007;2:265-71.
- Vichinsky EP. Clinical manifestations of α-thalassemia. Cold Spring Harb Perspect Med. 2013;3:a011742.
- Öner C, Gürgey A, Öner R, Balkan H, Gümrük F, Baysal E, Altay Ç. The molecular basis of HbH disease in turkey. Hemoglobin. 1997;21:41-51.
- Lorey F, Charoenkwan P, Witkowska HE, Lafferty J, Patterson M, Eng B et al. HbH hydrops foetalis syndrome: a case report and review of literature. Br J Haematol. 2001;115:72-8.
- Yüregir GT, Aksoy K, Cürük MA, Dikmen N, Fei YJ, Baysal E et al. HbH disease in a turkish family resulting from the interaction of a deletional alpha-thalassaemia-1 and a newly discovered poly a mutation. Br. J. Haematol. 1992;80:527-32.
- Çürük MA, Kilinç Y, Evrüke C, Ozgünen F, Aksoy K, Yüreğir GT. Prenatal diagnosis of HbH disease caused by a homozygosity for the α2 poly A (AATAAA→ AATAAG) mutation. Hemoglobin. 2001;2:255-8.
- Fei YJ, Oner R, Bozkurt G, Gu LH, Altay C, Gurgey A et al. HbH disease caused by a homozygosity for the AATAAA>AATAAG mutation in the polyadenylation site of the alpha 2-globin gene: hematological observations. Acta Haematol. 1992;88:82-5.
- Çürük MA, Dimovski AJ, Baysal E, Gu LH, Kutlar F, Molchanova TP et al. Hb adana or alpha 2(59)(E8)Gly>Asp beta 2, a severely unstable alpha 1-globin variant, observed in combination with the -(alpha) 20.5 kb alpha-thal-1 deletion in two turkish patients. Am. J. Hematol. 1993;44:270-5.
- Nainggolan IM, Harahap A, Ambarwati DD, Liliani RV, Megawati D, Swastika M et al. Interaction of Hb adana (HBA2: c.179G>A) with deletional and nondeletional α(+)-thalassemia mutations: diverse hematological and clinical features. Hemoglobin. 2013;3:297-305.
- Li Y, Liang L, Qin T, Tian M. Detection of HbH disease by long molecule sequencing. J Clin Lab Anal. 2022;36:e24687.
