LAMom, my syndrome is very rare, and they had NO clue about it in Boston.
Yes, have them test for 18p-. The geneticist in charge of things at the Chromosome 18 Registry says he thinks that 18p- might be really common and should be tested in ANY case where there's a severe spoken language delay. The trouble with testing is that a lot of docs still think that autosome (numbered chromosome) disorders= REALLY severe. Not quite......There are the stereotypical kids who have about ten million medical problems, and who are profoundly mentally handicapped but there are also normal IQ kids who are just HOH and have a lot of weird medical problems, or just kids who speak very late.