Madisons Foundation is an excellent resource for finding information on rare illnesses and diseases, including the a rare disease database  which provides information on a large number of rare diseases. Additionally, there is a parent matchingservice to connect parents with other parents with children of disorders such as Heterotaxy Syndrome.

Children's Heart Foundation

Sophie's Story - Wonderful account detailing the life and journey of Sophie Salmond, a girl born with Heterotaxy, written by her father.

Genetic Alliance - Organization devoted to promoting optimum health for people suffering from genetic disorders.

Finding Answers to Heterotaxy - Polysplenia and PDD NOS - Excellent blog on Heterotaxy and Polysplenia.

Heterotaxy Hope Organization

http://groups.yahoo.com/group/asplenia_ivemarks_syndrome - Internet group for people affected by Heterotaxy, Asplenia and other related conditions.

Heartline - An organization set up to offer help and support to families of children with heart disorders.

PCD Foundation is a foundation for information on Primary Ciliary Dyskinesia, a "progressive disorder affecting organ systems that rely on ciliary activity for proper function".  According to the PCD Foundation website, a small number of individuals with PCD also have Heterotaxy.

Research article from the the University of North Carolina at Chapel Hill School of Medicine showing a link between Heterotaxy Syndrome and Primary Ciliary Dyskinsia.

UNOS (United Network for Organ Sharing) - oversees the national database of clinical transplant information and operates the computerized organ sharing system, matching donated organs to those in need.