New NAD study

New study applies a novel method to identify NAD deficiency in families with multiple birth defects

16 February 2024

Scientists from the Victor Chang Cardiac Research Institute have shed further light on how a deficiency in a molecule called NAD during pregnancy is a cause of multiple birth defects, with many of the affected families experiencing miscarriage.

Professor Sally Dunwoodie and her team have developed a method to quantify NAD and related molecules and used it for the first time to see how levels of these molecules are altered in patients with birth defects caused by NAD deficiency.

It is hoped in the future that families affected by multiple birth defects and miscarriage might be able to access this new method and discover if NAD deficiency was the likely cause.

“There are so many unknowns when a family experiences multiple birth defects and miscarriages. If this new approach can identify the cause as NAD deficiency, and therefore a possible preventative, this could really help families in the future,” says Professor Dunwoodie, Deputy Director of the Victor Chang Cardiac Research Institute.

Severe birth defects are present in three to six percent of live born babies (four to eight million babies per year globally) and miscarriage occurs in up to 10-15 percent of clinically recognized pregnancies. The cause of these adverse pregnancy outcomes is unknown in about 50 percent of cases.

NAD is a vital molecule that is required in every cell in our body and has hundreds of important roles including being an energy producer. Our bodies produce NAD from two dietary sources, tryptophan and vitamin B3. When NAD levels are low during pregnancy, the embryo does not develop correctly.

How many cases of birth defects and miscarriage are caused by NAD deficiency is still unknown. Further research by the Institute’s team will help to address this question.

This new study, published in the Journal of Clinical Investigation, identified 10 families with a genetic condition that caused Congenital NAD Deficiency Disorder (CNDD), which is characterised by multiple birth defects and disrupted NAD metabolism.

The study generated mouse models which replicated the genetic condition of the families, resulting in NAD deficiency during gestation, multiple or isolated birth defects and embryo death during gestation.

Using a method already published by the team in Analytical Biochemistry that allows simultaneous quantification of NAD and 25 related molecules in as little as a drop of blood or plasma, the researchers discovered CNDD patients have a unique metabolic profile of NAD-related molecules.

Analysis of these patient blood samples allowed them to identify individuals with unique biochemical signatures indicating a specific genetic condition for NAD deficiency and evaluate the severity of such. It is hoped in the future this method will be available as a clinical test to determine if NAD deficiency was the cause of a baby’s birth defects.

The researchers also showed in mouse models with NAD deficiency that if the mother was provided with additional vitamin B3 in the diet, the birth defects and pregnancy loss could be prevented, and this was accompanied by characteristic changes in the levels of NAD-related metabolites.

“Birth defects are more common than many of us imagine, and their causes are largely unknown. Our five prior published studies in families and mouse models provide evidence that low levels of NAD can cause birth defects and pregnancy loss, and that in mice raising NAD levels with vitamin B3 can prevent these adverse outcomes," says Professor Dunwoodie.

“Whilst our study focused on mothers with a specific genetic predisposition to having lower levels of NAD, other scenarios can lead to women having lowered NAD levels – including pregnancy, high BMI, malnutrition, diabetes, inflammation, infections, or irritable bowel syndrome.

“Although the exact role NAD plays in a healthy pregnancy is yet to be fully determined, NAD deficiency should be easily avoidable if the body receives enough vitamin B3 to keep NAD levels high.”

This work follows on from an earlier breakthrough study, published in the New England Journal of Medicine, that reported the first families identified with extremely rare genetic mutations causing low NAD levels and severe birth defects. Since that study, the Dunwoodie laboratory has become the world leader in NAD-dependent birth defect research and become a point of contact for newly identified patients with CNDD.

To date around 40 patients have been identified with gene mutations causing CNDD, mostly by Professor Dunwoodie and colleagues. While it remains uncertain how common these cases are in the general population, this would suggest that many cases with isolated NAD deficiency-dependent defects or miscarriage may go undiagnosed.

Professor Dunwoodie’s team and her collaborators, Professor Natasha Nassar and Dr Antonia Shand, are also conducting a clinical study at the Royal Hospital for Women at Randwick in Sydney which will establish, for the first time, normal NAD levels in women and in pregnancy. The study can then determine what are low levels and the proportion of women with adverse pregnancy outcomes that have lowered levels of NAD. Those findings will help ascertain how much vitamin B3 will women need to take to get their NAD levels back up to a healthy normal range.

The results are currently being analysed and are expected to be published later this year.