Rare Diseases

While there are almost 8,000 rare diseases, we chose three that are near and dear to our heart.

Gilles was recently diagnosed with LGMD-T2, a disease likely to cause weakness and atrophy of the limb-girdle muscles. Jonas' dad was diagnosed about 10 years ago with a mutation of the C90RF72 gene which recently showed more prevalent symptoms related to FTD and ALS. At this time, no known cure is available for FTD, ALS, or LGMD.


Frontotemporal dementia is an umbrella term for a group of brain disorders that primarily affect the frontal and temporal lobes of the brain. These areas of the brain are generally associated with personality, behavior and language. In frontotemporal dementia, portions of these lobes shrink (atrophy).

Frontotemporal dementia can be misdiagnosed as a psychiatric problem or as Alzheimer's disease. But frontotemporal dementia tends to occur at a younger age than does Alzheimer's disease. Frontotemporal dementia often begins between the ages of 40 and 65 but occurs later in life as well. FTD is the cause of approximately 10% to 20% of dementia cases.


Signs and symptoms of frontotemporal dementia can be different from one individual to the next. Signs and symptoms get progressively worse over time, usually over years:

  • Behavioral changes (increasingly inappropriate social behavior, lack of judgement, lack of interest (apathy), etc.)

  • Speech and language problems (trouble naming things, no longer knowing word meanings, etc.)

  • Motor disorders (tremor, muscle spasms, difficulty swallowing, falls or walking problems, etc.)


There are genetic mutations that have been linked to frontotemporal dementia, mainly through a mutation in one of three genes: C90RF72, MAPT, or GRN. But more than half of the people who develop frontotemporal dementia have no family history of dementia.

Recently, researchers have confirmed shared genetics and molecular pathways between frontotemporal dementia and amyotrophic lateral sclerosis (ALS).


Amyotrophic lateral sclerosis (a-my-o-TROE-fik LAT-ur-ul skluh-ROE-sis), or ALS, is a progressive nervous system disease that affects nerve cells in the brain and spinal cord, causing loss of muscle control.

ALS is often called Lou Gehrig's disease, after the baseball player who was diagnosed with it. Doctors usually don't know why ALS occurs. Some cases are inherited.


Signs and symptoms of ALS vary greatly from person to person, depending on which neurons are affected. It generally begins with muscle weakness that spreads and gets worse over time. Signs and symptoms might include:

  • Difficulty walking

  • Tripping and falling

  • Hand weakness

  • Slurred speech or trouble swallowing

  • Cognitive and behavioral changes

Some people with ALS have problems with memory and decision-making, and some are eventually diagnosed with a form of dementia called frontotemporal dementia.


ALS affects the nerve cells that control voluntary muscle movements such as walking and talking (motor neurons). ALS causes the motor neurons to gradually deteriorate, and then die. Motor neurons extend from the brain to the spinal cord to muscles throughout the body. When motor neurons are damaged, they stop sending messages to the muscles, so the muscles can't function.

ALS is inherited in 5% to 10% of people. For the rest, the cause isn't known.


Limb-girdle muscular dystrophy (LGMD) is a diverse group of disorders with many subtypes categorized by disease gene and inheritance. LGMD usually manifests in the proximal muscles around the hips and shoulders.

The shoulder girdle is the bony structure that surrounds the shoulder area, and the pelvic girdle is the bony structure surrounding the hips. Collectively, these are called the limb girdles, and it is the observed weakness and atrophy (wasting) of the muscles connected to the limb girdles that has given this group of disorders its name.


The age at which symptoms appear, and the speed and severity of disease progression, can vary:

  • Weakness of the hip and leg muscles (trouble getting out of chairs, rising from toilet seat, etc.)

  • Weakness in the shoulder area (difficulty carrying heavy objects, combing one's hair, type on a keyboard, etc.)

  • Joint stiffness, muscle cramps, enlargement of calf muscles, etc.


LGMD is typically caused by a mutation in genes encoding proteins that play vital roles in muscle function, regulation, and repair.

There are two major groups of LGMDs. Called LGMD1 and LGMD2, these two groups are classified by the respective inheritance patterns: autosomal dominant and autosomal recessive. If one copy of the abnormal gene is sufficient to cause the disease, it is said to be autosomal dominant; if two copies are needed, then the inheritance pattern is autosomal recessive. In some families, the inheritance pattern cannot be determined.

Dozens of different genes, when mutated, have been shown to cause specific LGMD1 and LGMD2 subtypes. In these cases, the proteins associated with these genes are nonfunctional or deficient, and muscles are unable to function normally. Gradually, the muscles become weak enough that people experience the symptoms of LGMD.