A 60-year-old woman was referred because from the age of 50 years onwards she experienced muscle weakness that led to increasing difficulty in climbing stairs. In addition, she complained about exercise-induced myalgia.

History included cataract surgery at the age of 58 years, and lately, unexpected and unexplained falls. Family history revealed early-onset cataract in several paternal family members. Her father and brother had died suddenly and unexpectedly despite a pacemaker.

A 35-year-old man complained about muscle stiffness and weakness, especially when initiating a movement. He had experienced these symptoms for as long as he could remember. They were present in his eyes, jaws, tongue, and limb muscles. He had noticed that cold weather had a negative influence. He was not able to run and did not participate in team sport activities. In spite of these symptoms, he experienced no limitations in activities of daily living. He was referred because he had been informed elsewhere about possible treatment. The family history revealed similar symptoms in a sister and a brother, but not in the parents. His father’s grandparents were cousins.