Researchers at Kuwait University and Amri Hospital, Kuwait have been the first to study the risk of the FTO allele rs9939609 on disability progression in patients with multiple sclerosis (MS). This allele has been thoroughly studied in its link with obesity, however no study has linked the FTO gene to MS. The study published in Nature genotyped a single nucleotide polymorphism (SNP) rs9939609 in 200 patients and identified an allele that could indicate a higher risk of disease progression in patients with MS and obesity.

MS affects over 2.2 million people worldwide and is a chronic demyelinating autoimmune disorder of the central nervous system. The average age of onset is 20-40 years old and is ~2 to 3 times more common in women than men. It’s unclear exactly what causes this disorder and it’s believed to be combination of genetic and environmental factors. Obesity has been previously been identified as a risk factor for multiple diseases such as MS, but a genetic link remains unfound.

The study was carried out in Kuwait, a country where ~50% of the population is overweight/obese. 200 MS patients (135 females and 65 males) and 206 healthy controls (125 females and 91 males) were genotyped for the FTO rs9939609 polymorphism. The A allele was found to be associated with an increased weight in MS patients and increased MS disability. However, no association was found in the risk of developing MS. There was a significant difference observed in the AA genotype in the overweight or obese group compared to the BMI normal group. (29.9% compared to 14.5%)

The Fat-mass obesity (FTO) gene has been previously studied and many variants have been identified with obesity risk. The exact function remains unknown, but most studies have looked at its role as a regulator of fat mass, adipogenesis and energy homeostasis. In 2007, the variant rs9939609 in the FTO gene was found to be associated with increased BMI in both children and adults, and this is consistently shown in studies across different populations.

As the first study to detect a risk allele in MS patients that confers a greater risk of MS progression, genotyping could be useful for clinicians to identify which patients are at higher risk of disability progression and intervene before it’s too late.