DNA testing for sickle cell anemia in Africa: Implementation choices for the Democratic Republic of Congo.

BACKGROUND: Hemoglobin-based tests form the reference diagnostic test for SCA. In limited resource countries, these tests face limitations including cost, low sensitivity due to recurrent transfusions in endemic malaria region, and interference from fetal hemoglobin in neonatal diagnostic. This study aimed at adapting DNA-based SCA tests to limited resource countries and evaluating the economic benefit. METHODS: 338 participants were recruited in the Democratic Republic of Congo, sorted in 3 cohorts based on venous blood, umbilical cord blood (UCB) and buccal swab sampling. RFLP was performed to identify mutated allele. The feasibility and technical validity of this RFLP was evaluated for specimens collected on DBS cards and on EDTA tubes. RFLP on DBS stored at room temperature was regularly repeated to assess sample conservation. Finally, the cost analysis was performed. RESULTS: DBS cards yielded identical results to extracted DNA. Repeated testing returned the same result after four years. The DBS-based test performed on UCB or on buccal swab had a sensitivity and a precision of 100%. Cost comparison indicated that our approach costs half price of the widely used isoelectrofocussing of hemoglobin. CONCLUSION: The implemented DNA-based test approach overcomes the limitations faced by hemoglobin-based tests, while being more affordable. We propose to implement the RFLP test as a first line diagnostic test after transfusion and as second tiers for newborn screening. However, users should be aware that this test is unable to differentiate HbC from HbS or identify other point mutation of gene deletion of HBB gene.

Phenotype and growth in Sotos syndrome patient from DR Congo (Central Africa).

Sotos syndrome is a widely studied overgrowth syndrome. Clinical presentation includes excessive growth during childhood, macrocephaly, learning difficulties of various degrees, variable minor features, and distinctive facial gestalt. We provide in this report the first phenotypic and growth description of Sotos syndrome in a patient from Central Africa. At 6 month the patient exhibited axial hypotonia, delayed speech development and dysmorphism including long face, sparse eyebrows, hypertelorism, malar hypoplasia and dark flushing, short philtrum, depressed nasal root, anteverted nares, thick upper and lower lip vermilions, macroglossia, prominent forehead, large and peculiar ears, wide intermammillary distance, deep palmar creases, dysplastic finger nails, partial syndactyly of toes, broad, and overlapping hallux. At 19 months, malar flushing became reddish and a retraction of the middle of the lower lip was observed, resembling a bifid lip. He retained the same clinical features at 31 months. Head circumference, weight, and height where within normal ranges at birth but became all above 97th centiles at 4 months. The height velocity evolved in three phases starting with a very fast growth from birth to 6 months (54 cm/year), then a fast phase from 6 to 16 months (18 cm/year) and a slow phase from 16 to 31 months (4.8 cm/year). Conversely, the patient exhibited an acceleration of weight after the first year of life. Our patient exhibited very prominent lips and deep philtrum, which are common facial traits in African individuals. The current report shows an admixture of ethnic-specific features with syndrome-specific features in an African patient.