NEWS


HEALTHCARE Vitamin link to birth defects MARIA BURKE


Australian scientists have found that a rare genetic deficiency of a particular enzyme can lead to birth defects in the developing baby. The team also showed, however, that in mice with the same genetic deficiency these birth defects are potentially treatable if the mother is given vitamin B3 supplements during pregnancy. The paper identifies gene variants in two enzymes in a biochemical pathway that makes Nicotinamide Adenine Dinucleotide (NAD), a co- enzyme important in cellular metabolism. As well as being produced in the body, NAD can be also be sourced from dietary niacin, also known as vitamin B3.


The authors from seven universities undertook


whole genome sequencing in 13 affected families (N. Engl. J. Med., doi: 10.1056/NEJMoa1616361). The gene variants were identified in four families - three with ‘consanguineous’ marriages, when close relatives marry - with children with complex birth defects including abnormalities in heart, spine and kidneys and other systems: a syndrome called VACTERL. Babies born to consanguineous marriages are more likely to inherit two copies of defective genes that can cause malformations. Inheriting one copy often does not cause problems because the healthy copy can compensate. The team, led by Sally Dunwoodie of the Victor


Chang Cardiac Research Institute in Sydney, also genetically engineered mice to show that absence of the genes caused NAD deficiency and similar malformations in mice. However, when they provided extra niacin to pregnant mice, the pups were born healthy and without birth defects despite the absent gene. Sarah Stock of the MRC Centre for Reproductive


Health, University of Edinburgh, UK, says this is exciting new research. ‘The results suggest that some complex birth defects in babies – for example, some cases of VACTERL - might be caused or worsened by low levels of vitamin B3 in the mother. This suggests that vitamin B3 supplements might help prevent certain types of birth defects. However, it must be emphasised that this work was done in mice and it is much too early to say if women should start taking extra vitamin B3. More research is needed to discover if dietary supplements of vitamin B3 work in humans, and what doses are safe.’ Katie Morris, a


consultant in maternal fetal medicine at the University of Birmingham, UK, also points out that the research findings cannot be translated into recommendations for pregnant women. ‘In particular, the doses used in this research were ten times the recommended daily doses for supplementation in women and it is known that high doses of vitamin B3 can cause side-effects for the mother, and the long-term effects on pregnancy and health of children are not known. Most pregnancy complications, including structural differences in babies, are due to a complex interaction of factors such as genes, the environment and other conditions in the mother such as diabetes and obesity, and thus at present this finding is not relevant to pregnant women as a whole.’


B3 to beat skin cancer


Australian researchers say a daily dose of vitamin B3 could be a cheap way of preventing skin cancer. They are calling for further clinical trials of a form of vitamin B3 called nicotinamide in high risk individuals. Even low doses of UV cause DNA


damage to skin, which can trigger genetic mutations and lead to cancer. Nicotinamide, or niacinamide (NAM), an amide form of vitamin B3 (niacin), is involved in a number of DNA repair mechanisms, and has been shown to enhance DNA repair in skin irradiated with UV, as well as significantly reducing suppression of the immune system induced by UV. Over one year, a team from the


University of Sydney studied 386 participants recruited from a population at high risk of developing skin cancers. They found that NAM was effective at reducing the incidence of non-melanoma skin cancer (NMSCs) in high-risk individuals (Photodermatology, Photoimmunology & Photomedicine, doi: 10.1111/phpp.12328). Non-melanoma skin cancer refers to a group of cancers that slowly develop in the upper layers of the skin and differs from the less common skin cancer known as melanoma, which can be more serious. The study did not assess the effect of NAM on the development of melanomas. To assess melanoma incidence, team leader


Gary Halliday says they would need a longer trial period, and a much larger study cohort, as melanomas occur much less frequently than NMSCs. But he says it would definitely be worthwhile to investigate using NAM to prevent melanoma in high-risk patients. The cost of NAM is only about Aus$10/ month, if taken at 1g/day as recommended, he adds. Terry Slevin, Chair of Cancer Council


Australia’s Occupational and Environmental Cancer Risk Committee, says he would welcome such clinical trials, but believes it is important to await the outcome before recommending vitamin B3 as a means of preventing skin cancer.


10 08 | 2017


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