Impact of Haplotypes on the Frequency of Morbid Complications in Homozygous SSFA2 Sickle Cell Disease in Cote D ivoire

Research Article

Austin Hematol. 2021; 6(3): 1043.

Impact of Haplotypes on the Frequency of Morbid Complications in Homozygous SSFA2 Sickle Cell Disease in Cote D’ivoire

Silue DA¹*, Ndhatz E¹, Ayemou R², Kouakou B¹, Nanho DC¹, Kamara I¹, Meite N¹, Bognini AS¹, Botti RP², Kouakou I¹, Djeket R¹ and Koffi KG¹

¹Clinical Hematology Unit, Yopougon University Hospital of Abidjan, Cote d’Ivoire

²Clinical Hematology Unit, University Hospital of Bouaké, Cote d’Ivoire

*Corresponding author: Silue DA, Clinical Hematology Unit, Yopougon University Hospital of Abidjan, 09 BP 1692 Abidjan 09, Cote d’Ivoire

Received: November 15, 2021; Accepted: December 07, 2021; Published: December 14, 2021


Background: Sickle cell disease is a constitutional hemoglobin disease witch poses a public health problem in Côte d’Ivoire due to its prevalence and complications. The homozygous form (SSFA2) is the most severe. The proportion of hemoglobin F by its property determines the haplotype. Authors wanted to determine the impact of these haplotypes on the frequency of morbid complications.

Methods: Our study was a transversal type and analytical aims, occurred in the clinical hematology department of the University Hospital of Yopougon over a 3 months period. Our study included 150 SSFA2 patients with complications. The statistical test used was the student.

Results: The mean age was 11 years, (6 months to 42 years). The sex ratio was 1.05. The mean rate of hemoglobin S was 86%, of which 17% had severe haplotype, 37% intermediate haplotype, and 45% benign haplotype. Infectious complications were the most frequent (58.72%) (Malaria 53.47%; bronchial pneumonia: 28.22%), followed by anemic complications (36.92%) and ischemic complications (4.36%). Deglobulization crisis was the major acute anemic complication (97.5%) followed by splenic sequestration (2.5%). Chronic anemic complications were dominated by leg ulcers (57.14%) followed by biliary lithiasis (42.86%). Aseptic necrosis of the femoral head was the most frequent ischemic complication (46.66%), followed by retinopathy (33.33%), and then stroke (20%). The severe haplotype was associated with a high frequency of complications in general and infectious complications in particular. (P=0.005)

Conclusion: The clinical expression of the SSFA2 homozygous form and the occurrence of complications is closely related to the haplotype.

Keywords: Complications; SSFA2; Sickle cell disease; Haplotypes


RBC-SS: Red Blood Cell - SS; Hb: Hemoglobin; MCHC: Mean Corpuscular Hemoglobin Concentration; RR: Relative Risk; CI: Confidence Interval


Sickle cell disease is a hereditary disease related to an abnormality in the structure of hemoglobin (Hb). It is characterized by the substitution of Glutamic acid (Glu) at position 6 on the β-chain by valine (val), resulting in the synthesis of an abnormal hemoglobin called HbS. Genetically, the GAG codon is substituted by GTG. In Côte d’Ivoire, this disease affects 12% of the population, of which 2% are severe according to a study by Cabannes [1]. It represents a real public health problem due to its frequency and potential severity. It is a disease whose evolution is marked by iterative, hemolytic, and/ or ischemic vascular occlusive painful crises, but especially by the occurrence of anemic, ischemic and infectious complications.

During the last three decades, the therapeutic management of patients has improved considerably, allowing an increase in life expectancy and consequently an increase of the population with sickle cell disease, which has been associated with a parallel increase in the incidence of complications. In contrast to hemoglobin S, hemoglobin F (HbF) does not bind 2-3 DPG, hence its hyper affinity for oxygen (O2), which gives it the property to inhibit the polymerization of hemoglobin and therefore the sickling of the SS red blood cell. The proportion of hemoglobin F in the SS red blood cell over and above the MCHC, hematocrit, blood viscosity, mechanical properties, and the surface/volume ratio of the SS RBC; determines the haplotypes of the SSFA2 phenotype. The severity of the SS haplotype should therefore be inversely proportional to the level of hemoglobin F in the RBC-SS [2]. Considering by definition that in the homozygous form, the proportions vary between: 2 and 20% (HbF); between 77% and 96% (HbS), and 2 to 3% (HbA2), the Haplotype is said to be severe if HbF <5%; intermediate Haplotype if HbF >10% and <5% and benign Haplotype if HbF >10%) [3].

The authors wanted to determine their impact on the frequency of morbid complications in SSFA2 sickle cell disease in the clinical hematology department of the University Hospital of Yopougon.

Study Material and Methods

Our study occurred in the clinical hematology department of the University Hospital Center of Yopougon in Abidjan, Ivory Coast. It was a prospective cross-sectional study with a descriptive and analytical aim on SSFA2 homozygous sickle cell patients with morbid complications. Our study took place from November, 2015 to March, 2017, i.e., 3 months or approximately 100 days.

150 patients with well-documented records of SSFA2 homozygous major sickle cell disease with at least one complication were analyzed according to systematic random sampling. They were divided into benign, intermediate, and severe haplotypes forming 26; 56 and 68 patients, respectively. Epidemiological, clinical, and paraclinical data were collected.

After separating the patients according to the different haplotypes that we have defined, we performed a comparative analysis using the Epi-Info 6.04 b statistical software. The statistical test used was the Student test. For the P value, the significance level was 0.05. The adjusted Relative Risk (RR) and 95% Confidence Interval (CI) were used to assess the significance of the observed differences.


The mean age in the present study was 11 years, with extremes ranging from 6 months to 42 years. The diagnosis was made for the majority after 1 year old for an average of 4 years and extremes from 6 months to 13 years. There was a predominance of subjects from 0 to 10 years old with a percentage of 53.3% of cases with a peak of frequency for patients over 15 years (36.66%) and the sex ratio was 1.05 (Table 1).