As enthusiasm for dumping ice on one another fades with autumn and October brings pervasive pink, I wish that attention would turn to families confronting diseases not as well known as ALS and breast cancer.
HOW RARE IS RARE?
According to the National Organization for Rare Disorders
, “rare disease” in the U.S. means affecting fewer than 200,000 people. These conditions number about 6,800, collectively affecting nearly 30 million Americans or 1 in 10 people.
Many are single-gene diseases. That means that the chance of more than one family member being affected is quite high (see Mendel's first law). Unlike those, most (>90%) cases of ALS and breast cancer aren’t inherited as single-gene traits, but are sporadic. Mutations happen during a person’s lifetime in somatic cells, perhaps due to an environmental trigger. A family with one member who has ALS wouldn't have as great a chance as it affecting another as a family with Huntington disease, for example.
With so many causes of rare diseases, comparing statistics is an apples-and-oranges exercise. But I collected a few anyway, for prevalence (the percentage of a population with a particular disease at a given time). (more…)