Phenotypic expression of the 3120+1G>A mutation in non-Caucasian children with cystic fibrosis in South Africa

Abstract

Introduction: Cystic fibrosis (CF) is the most common genetic disorder in Caucasians. Presentation of CF in non-Caucasians is less well studied.

Objective: This audit was undertaken to determine the phenotypic expression of the 3120+1G>A mutation in black and mixed race children in South Africa.

Methods: A multi-centre retrospective chart review of clinical, laboratory and spirometry data of non-Caucasian CF patients in four CF centres in South Africa was collected. Data was collected at diagnosis and after a five-year follow-up period. Ethical approval was granted for the study.

Results: A total of 30 participants were enrolled of whom 14 (47%) were homozygous and 16 (53%) heterozygous for the 3120+1G>A mutation. The mean age of diagnosis was 13 months. Twenty-four (80%) patients had malnutrition (mean weight z-score -3.6) or failure to thrive (77%) at presentation. Twenty (67%) presented with non-specific abdominal symptoms, whilst fifteen (50%) had recurrent respiratory tract infections. Pseudomonas aeruginosa was detected at a mean age of 21 months. The mean FEV1 was 73% predicted (95% CI 54.0-91.1) at study entry and 68% predicted (95% CI 49.74-87.06) at follow-up.

Conclusion: Failure to thrive and a diagnosis of protein energy malnutrition (kwashiorkor) are the common presenting features of CF in children with the 3120+1G>A mutation. Meconium ileus is a rare presenting feature of CF in black and mixed race children with this deletion in South Africa.