Amy brings her 4 year old son, George, into the GP practice as she is concerned about the appearance of dark brown skin freckling inside and around his mouth and eyes. Amy says his dad had a similar appearance and mentioned having a related genetic condition before he left them many years ago. On examination, you observe dark brown/bluish macules on the lips, buccal mucosa, hands, feet, and anus.
You have a strong initial working diagnosis and explain the likely condition. Which one of the following statements is least correct regarding his likely condition?