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Prenatal Genetic Diagnosis of Sickle Cell Disease: Preliminary Experiences: Cameroon

Author(s): Ambroise Wonkam1,2, Cedrik Ngongang Tekendo1, Huguette Zambo1 and Michael A. Morris3
Affiliation(s): 1Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Cameroon, 2Division of Human Genetics, University of Cape Town, Cape Town, South Africa, 3Service of Genetic Medicine, Geneva University Hospitals, Geneva, Switzerland
1st country of focus: Cameroon
Relevant to the conference theme: Medicines and diagnostics
Summary (max 100 words): The practice of prenatal genetic diagnosis of sickle cell disease is possible in Cameroon. To the best of our knowledge, the present study is the first report of PND experience in the Central African region.
Background (max 200 words): The Republic of Cameroon is a sub-Saharan African country with a population of about 20 million. The health-care system of the country is organized into the public, orthodox private and traditional private sectors. There is no universal medical insurance coverage in Cameroon. With a carrier frequency of 8 to 34%, the country has developed a national control program for sickle cell anaemia (SCA). Nevertheless, prenatal genetic diagnosis (PND) has not yet been incorporated in this strategy. Despite a low acceptance (36.1%) of the termination of an affected pregnancy (TAP) for SCA by Cameroonian physicians, up to 95% of Cameroonian parents with an SCA-affected child would request PND and 65% would opt for TAP. PND for SCA was initiated in Cameroon in August 2007.
Objectives (max 100 words): The main objective of the present study is to discuss the preliminary evaluation of the 36-month practice of prenatal genetic diagnosis of sickle cell anemia in Cameroon.
Methodology (max 400 words): The study included all patients consulted regarding PND of SCA from August 2007 to January 2011.  Fetal sampling was performed under ultrasound guidance by two obstetricians. Informed written consent was obtained from each patient. All the DNA samples of the parents and that of the fetus were extracted in Yaoundé, from peripheral blood and amniotic fluid, respectively, following instructions on the available commercial kits (Puregene blood kit®, Qiagen®, USA; and NucleoSpin® Blood QuickPure, Macherey-Nagel GmbH & Co ®, Germany). The molecular analyses for all the cases were done in the Service of Genetic Medicine of Geneva University Hospitals, Switzerland. Molecular analysis for the sickle cell mutation was carried out by PCR-restriction fragment length polymorphism (thermocycler from BIORAD®, USA; Dde I restriction enzyme from by GIBCO-BRL®, USA). In addition, any maternal contamination was also excluded. Maternal contamination was picked up on one occasion and the amniocentesis was repeated.
Results (max 400 words): A total of 42 patients presented for PND of SCA. Most patients were university graduates of Christian faith.  Amongst them, 93.9% had a family history of SCA, with either an SCA-affected child (59.5%; N = 25) or SCA-affected sibling (35.7%; N = 15). The possibility of having a child with SCA was not realized by 85.7% (N = 36) before marriage. Prior to the availability of PND in Cameroon, nine parents (21.4%) admitted to having voluntarily terminated at least one pregnancy for fear of having an SCA-affected child. The majority of patients (90.4%; N = 38) were counseled by the medical geneticist. Following counselling, two patients declined PND because of financial reasons; one for religious reasons and one had a spontaneous abortion prior to the scheduled date of amniocentesis. Thirty-eight patients underwent transabdominal amniocentesis, at an average gestational age of 16.3 weeks (range 13–23 weeks) with two procedure-related abortions. Late amniocentesis (above 21 weeks) was carried out on three patients (7.9 %). Three cases required repetition of amniocentesis; the reasons were maternal contamination (1/3) and failure of DNA extraction (2/3). Polymerase chain reaction-restriction fragment length polymorphism revealed ten fetuses affected with SCA (26.3%). Nine of these SCA-affected pregnancies (90%) were terminated.  The only patient who declined termination of an SCA-affected pregnancy stated ethical reasons; the pregnancy was 24 weeks at the time of result delivery, because of late referral and transportation time of the DNA samples to Geneva.
Conclusion (max 400 words): The practice of PND of SCA is possible in Cameroon. There is a need for open discussion of its ethical and legal challenges. The preliminary experience emphasizes the need for national and international collaborative efforts to overcome the lack of human, technical and financial resources.

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