Larsen Syndrome is considered to a  skeletal dysplasia disorder (abnormal skeletal system).  Below is a link to centers across the United States for treatment or referrals.

http://www.lpaonline.org/regional-skeletal-dysplasia-clinics

Additionally, many Shriner’s Hospital for Children have experience treating patients with Larsen Syndrome

https://www.shrinershospitalsforchildren.org

The LSRC does not endorse any treatment center.  Above is for information only.