BACKGROUND:In October 2003 South Africa embarked on a program of folic acid fortification of staple foods. We measured the change in prevalence of NTDs before and after fortification and assessed the cost benefit of this primary health care intervention. METHODS: Since the beginning of 2002 an ecological study was conducted among 12 public hospitals in four provinces of South Africa. NTDs as well as other birth defect rates were reported before and after fortification. Mortality data were also collected from two independent sources. RESULTS: This study shows a significant decline in the prevalence of NTDs following folic acid fortification in South Africa. A decline of 30.5% was observed, from 1.41 to 0.98 per 1,000 births (RR = 0.69; 95% CI: 0.49-0.98; p = .0379). The cost benefit ratio in averting NTDs was 46 to 1. Spina bifida showed a significant decline of 41.6% compared to 10.9% for anencephaly. Additionally, oro-facial clefts showed no significant decline (5.7%). An independent perinatal mortality surveillance system also shows a significant decline (65.9%) in NTD perinatal deaths, and in NTD infant mortality (38.8%). CONCLUSIONS: The decrease in NTD rates postfortification is consistent with decreases observed in other countries that have fortified their food supplies. This is the first time this has been observed in a predominantly African population. The economic benefit flowing from the prevention of NTDs greatly exceeds the costs of implementing folic acid fortification.

To ensure efficient genome duplication, cells have evolved numerous factors that promote unperturbed DNA replication, and protect, repair and restart damaged forks. Here we identify DONSON as a novel fork protection factor, and report biallelic DONSON mutations in 29 individuals with microcephalic dwarfism. We demonstrate that DONSON is a replisome component that stabilises forks during genome replication. Loss of DONSON leads to severe replication-associated DNA damage arising from nucleolytic cleavage of stalled replication forks. Furthermore, ATR-dependent signalling in response to replication stress is impaired in DONSON-deficient cells, resulting in decreased checkpoint activity, and potentiating chromosomal instability. Hypomorphic mutations substantially reduce DONSON protein levels and impair fork stability in patient cells, consistent with defective DNA replication underlying the disease phenotype. In summary, we identify mutations in DONSON as a common cause of microcephalic dwarfism, and establish DONSON as a critical replication fork protein required for mammalian DNA replication and genome stability.

Twenty-six highly polymorphic markers were used to determine the origin of the extra haploid chromosome set in 6 triploid fetuses of type II phenotype. All had reached the third trimester of pregnancy. The extra set was maternal in origin in all cases, supporting previous research indicating longer in utero survival of maternally-derived triploid fetuses. These findings provide evidence for an instance of genomic imprinting in humans.

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Corresponding author: A Vorster (vorster@sun.ac.za)Background. A relatively high frequency of autosomal recessively inherited osteogenesis imperfecta (OI) type 3 (OI-3) is present in the indigenous black southern African population. Affected persons may be severely handicapped as a result of frequent fractures, progressive deformity of the tubular bones and spinal malalignment. Objective. To delineate the molecular basis for the condition. Methods. Molecular investigations were performed on 91 affected persons from seven diverse ethnolinguistic groups in this population. Results. Following polymerase chain reaction amplification and direct cycle sequencing, FKBP10 mutations were identified in 45.1% (41/91) OI-3-affected persons. The homozygous FKBP10 c.831dupC frameshift mutation was confirmed in 35 affected individuals in the study cohort. Haplotype analysis suggests that this mutation is identical among these OI-3-affected persons by descent, thereby confirming that they had a common ancestor. Compound heterozygosity of this founder mutation was observed, in combination with three different deleterious FKBP10 mutations, in six additional persons in the cohort. Four of these individuals had the c.831delC mutation. Conclusion. The burden of the disorder, both in frequency and severity, warrants the establishment of a dedicated service for molecular diagnostic confirmation and genetic management of persons and families with OI in southern Africa.