The male child presented with pale, bulky stools and bronchiectasis. The female infant was admitted to hospital because of failure to thrive and a respiratory infection. 5 The next case report was of two unrelated Kikuyu infants from Kenya. A second case was mentioned in the appendix. 5 This infant had meconium ileus and died soon after birth. The first case of a South African CF child, of Bantu speaking parents, was reported in 1959. This may be because CF is being underdiagnosed because of confounding diagnoses, such as malnutrition, chronic pulmonary infections, and tuberculosis. In contrast, there have been very few reports of CF in African blacks with minimal caucasoid admixture. The ΔF508 mutation, presumably introduced by admixture, accounts for a further 48%. Macek et al 4 found that African-Americans have their own subset of “common” CFTR mutations. 2 This suggests that admixture alone, estimated at 30% in African-Americans, 3 does not account for CF observed in this population group, and that there must therefore be CFTR mutations which originated in the black population. 1 Haplotype and mutation analysis of the CFTR gene in African-American CF patients has shown a significantly different profile from that observed in white CF patients. Some of these are misdiagnosis as chronic pulmonary infection, malnutrition, tuberculosis, infantile diarrhoea, failure to thrive, or a high infant mortality rate.Ĭystic fibrosis (CF) has been extensively studied in the African-American population where the incidence has been estimated at 1 in 15 000, giving a heterozygote or carrier frequency of 1 in 61. There are several possible reasons why these people are not being detected. Hence, the incidence of CF would be predicted to be between 1 in 784 and 1 in 13 924 births in this population. Since this mutation accounts for between 15% and 65% of CF chromosomes in South African blacks, a corrected CF carrier frequency would be between 1 in 14 and 1 in 59. The 3120+1G→A mutation has a carrier frequency of 1 in 91 (8/728) in South African blacks with a 95% confidence interval of 1 in 46 to 1 in 197. A further three CFTR mutations, A559T, S1255X, and 444delA, which had been found in African-American CF patients, were not identified in the patients or in over 373 healthy subjects tested.
In addition, two out of five black CF patients with positive sweat tests were found to be heterozygous for the 3120+1G→A mutation and two out of another four black patients with symptoms suggestive of CF, but unconfirmed by sweat tests, were heterozygous for the D1270N mutation. In order to determine the carrier frequency of the 3120+1G→A mutation in Africa, 1360 unrelated, healthy subjects were screened. It has also been found in 4/6 CF chromosomes in South African blacks and one CF chromosome of Cameroonian origin. A CFTR mutation, 3120+1G→A, which was first reported in three African-American CF patients, has been shown to account for 9-14% of African-American CF chromosomes. The aim of this study was to determine if this is the case or whether it is under-reported. However, very little is known about CF in populations of African origin among whom it has been believed to be extremely rare. Cystic fibrosis (CF) is a common autosomal recessive disorder in populations of European descent.