Comorbidity of sickle cell trait and albinism: a cross-sectional survey in the Democratic Republic of the Congo

Co-occurrence of oculocutaneous albinism type 2 and mild sickle cell disease explained by HbS/βthal genotype in an individual from the Democratic Republic of Congo

Oculocutaneous albinism type 2 (OCA2) is a pigmentation disorder characterized by hypopigmentation of the skin, hair and eyes and ocular features. Sickle cell disease (SCD) is caused either by homozygosity of the beta globin gene variant c.20A > T/p.Glu6Val giving rise to severe anemia or by combined abnormal hemoglobins (HbS/βthal) leading to mild SCD. We report a 45 years old female patient from the Democratic Republic of Congo affected with these two disorders. She presented with creamy white skin and numerous pigmented patches called dendritic freckles, nystagmus, foveal hypoplasia grade 2, photophobia and very poor visual acuity. Sequencing of the OCA2 gene identified the common exon 7 deletion and a new pathogenic variant c.1444A > C/p.Thr482Pro. She had mild SCD with a total Hb level of 101 g/l. Hbβ sequencing identified variants c.20A > T giving rise to HbS and c.315 + 1 G > A characteristic of β-thalassemia. A heterozygous 3.7 kb deletion of the α globin gene was also found. The combined Hbβ/α globin genotype explains the mild SCD phenotype. Co-occurrence of OCA2 and SCD raises the question whether the patient's phenotype simply results from the addition of the two diseases' phenotypes or whether interaction between the two diseases modulates the phenotype of each other.

Co-occurrence of sickle cell disease and oculocutaneous albinism in a Congolese patient: a case report

BACKGROUND

Sickle cell disease and oculocutaneous albinism are rare autosomal recessive disorders both related to mutations on chromosome 11. The diagnosis of patients suffering from both pathologies is necessary to enable dedicated monitoring of any complications at the ophthalmic and skin level. However, few cases are described in the literature.

CASE PRESENTATION

A 14-month-old Congolese male child affected by oculocutaneous albinism, presented with pallor and jaundice. Blood indices revealed severe hemolytic anemia, which led to the diagnosis of sickle cell disease. The patient received a blood transfusion and close follow-up.

CONCLUSIONS

The co-inheritance of sickle cell disease and oculocutaneous albinism is a reality in the Democratic Republic of Congo, although it is rarely described. Given the current state of our knowledge, specific surveillance, specifically regarding cutaneous and ophthalmological complications, should be offered in this particular population. To enable this dedicated follow-up, sensitization to screening for sickle cell anemia in albino individuals should be carried out.