Chromosome 18p syndrome

18p syndrome occurs when any piece of the short arm of Chromosome 18 is missing. There are three classes of Chromosome 18 deletion syndromes; 18q, 18p, and Ring 18. Deletion syndromes of Chromosome 18 are the second most common of the autosomal deletion syndromes. Most deletions occur very early in the embryonic stage of development. There are several ways that this deletion can occur. Most children with 18p syndrome have parents who have normal chromosomes. The parent may also have a deletion on the chromosome, but the deleted piece is attached to another chromosome. As a result, the parent still has all of his or her genetic information; it is just arranged differently. This parent will not show any symptoms. Cases have also been reported in which a parent with 18p syndrome has a child with the same syndrome. Therefore, the chromosomal abnormality has been genetically passed on to the child. Because the genes that are missing vary and the content of the normal chromosome (the unaffected in the pair) can vary, the symptoms vary as well. Due to these variances, it is not possible to have a clear-cut list of symptoms. It is possible that a child might look a little different and has made it through school with Cs and Ds and actually has a chromosomal abnormality that was never diagnosed (Chromosome 18 Registry and Research Society, 1991). A belief exists that there are some people with 18p who are so mildly affected that they do not know they have a chromosomal abnormality until they have a child who is 18p and is more severely affected. There exists no evidence that this syndrome can be caused by environmental agents. It is important to note that most descriptions of this syndrome come from medical case reports. Due to the diagnostic nature of information available, very little is known about the outcomes for the affected individual (Chromosome 18 Registry and Research Society, 1991).