Myotonic dystrophy is not one thing. It is a cascade — genetic, metabolic, cardiac, hormonal, and neurological — that unfolds differently in each person. Some patients experience primarily muscle stiffness and weakness; others are hit harder by fatigue, cognitive changes, or arrhythmias.

If you are reading this, there is a good chance a doctor recently used the word "aspartylglucosaminuria" in a sentence about your child, or about you, and then moved on to the next appointment before you had time to write it down correctly.