Newly-discovered gene mutation blocks babies from metabolizing vitamin D

Researchers at the University of East Anglia, in England, have identified a new medical condition that caused the death of a baby 80 years ago.

The peer-reviewed study found that children, especially babies, with this condition cannot metabolize Vitamin D properly. This has led to a variety of symptomatic health problems such as calcium build-up in the blood, Kidney-damage and kidney stones.

The condition, now named infantile hypercalcemia type 1, is caused by a gene mutation. However, adding to the mystery, 10% of patients presenting the symptoms don’t have this mutation.

Many people do not know they have the condition until they are adults – when they suffer from frequent kidney stones and other ailments.

History of the condition

In the early 1900s, many children in the newly industrialized cities of Europe experienced a condition called ‘rickets.’ The condition led to bone pain, poor growth and weakened or deformed bones. It was soon discovered that sunlight, by supporting the absorption of Vitamin D, prevented rickets. So, children were often sent to enjoy a holiday in the countryside to prevent the illness alongside being given food with higher concentrations of Vitamin D.

Based on the new preventative understanding, Rickets was eliminated by the 1930s. However, soon after, infants were dying again.

More studies were conducted and it was soon found that dairy products with added Vitamin D were somehow contributing to the deaths. Many countries banned the supplementation of Vitamin D to prevent further losses. At the time, scientists weren’t certain why the supplements caused deaths.

It wasn’t until 2011 that researchers found a possible explanation. With the new discoveries of DNA and genetic testing, researchers were able to uncover a mutation named ‘CYP24A1.’ This condition prevents the metabolization of vitamin D and can be fatal. 

The study and findings

The study took a sample of 47 patients who were part of the 10% previously mentioned and looked at their genetic sequencing and blood samples. They found that the shape of the gene was abnormal.

 In response to this discovery, Dr. Green said they “carried out a more extensive genetic analysis of six patient blood samples and we found that the physical shape of the CYP24A1 gene in these apparent HCINF1 patients is abnormal…This tells us that gene shape is important in gene regulation - and that this is the reason why some people lived with HCINF1 but without a definitive diagnosis”, he added.

Prof. Bill Fraser, from both Norwich Medical School and the Norfolk and Norwich University Hospital, co-led the study and said “Genetic causes of vitamin D toxicity can be left undiagnosed for long periods, well into adulthood, sometimes coming to light during pregnancy when fortification of mothers with vitamin D happens. We also see patients with undiagnosed causes of recurrent renal stones who have had this condition for many years.” 

The treatment

The current recommended treatment is to avoid Vitamin D, although sunlight is thought to be safe. Some anti-fungal treatment has been thought to make improvements in the condition as it changes how vitamin D is metabolized.

Unfortunately, researchers have yet to find a cure for the condition so treatment options are more about management than cure.