SDHD is a ‘tumour protection’ gene that helps to protect against benign (non-cancerous) and malignant (cancerous) tumours.
Everyone has two SDHD genes (one from their mother, and one from their father). If one of these genes is not working, this is known as having a faulty SDHD gene, or having an SDHD mutation.
In almost all cases, the gene fault only increases the chance of developing tumours if it is inherited from a father.