Pendred syndrome is the autosomal recessively transmitted association of 
familial goiter and congenital deafness. There is no specific biochemical marker 
of this disease, and the diagnosis depends upon the demonstration of the triad 
of congenital sensorineural hearing loss, goiter, and abnormal perchlorate 
discharge test. Pendred syndrome is caused by mutations within the putative ion 
transporter gene (PDS gene), located on chromosome 7q. A wide variation in the 
clinical presentation of this condition, and its well documented phenotypic 
overlap with other thyroid disorders (such as Hashimoto's thyroiditis), can lead 
to diagnostic difficulties. The potential for misdiagnosis increases when these 
disorders occur coincidentally in the same family. We describe a kindred in 
which Pendred syndrome, autoimmune thyroiditis, and simple goiter coexisted, to 
highlight these diagnostic pitfalls and to illustrate the use of mutational 
analysis in resolving diagnostic confusion.