Spondyloepimetaphyseal dysplasia (SEMD), aggrecan type is a very rare disease that begins in infancy. SEMD, aggrecan type causes a person to be much shorter than most other people. SEMD, aggrecan type also causes bone growth problems.
Someone with SEMD, aggrecan type will have almost no nasal cartilage. The nasal cartilage is the soft bone-like structure that gives the nose its shape. SEMD, aggrecan type will cause the top and the bottom of the mouth to be misaligned. This means that either the top or the bottom of the mouth will stick out further than it should. SEMD, aggrecan type will also cause macrocephaly (large head).
SEMD, aggrecan type will cause growth problems in the femur (thigh bone) and the spine (the group of bones that run along a person’s back). The bones that make up the spine are called vertebrae. SEMD, aggrecan type will cause the vertebrae to be flat. It also causes short fingers and toes.
SEMD, aggrecan type is passed down from parents to their children through genes. Genes are segments of DNA that act as the body’s instruction manual. DNA is a “code” made up of small parts called nucleotides. A mutation is when one or more nucleotides in the DNA “code” that makes up a gene is changed. SEMD, aggrecan type is caused by a mutation in a gene called AGC1. AGC1 is a gene that codes for bone growth.
A person receives genes from both parents. SEMD, aggrecan type is inherited in an autosomal recessive pattern. This means that both parents must pass down a mutation to the child for the child to have SEMD, aggrecan type. If you or a family member has been diagnosed with SEMD, aggrecan type, talk to your doctor about the most current treatment options. Support groups are also good sources of support and information.