The results of the study, which were published in the journal Human Genetics, showed that most cases with holoprosencephaly had deletions of one of four major holoprosencephaly genes, which is consistent with previous studies. Interestingly, several individuals with deletions of genes that had previously only been hypothesized to be associated with holoprosencephaly had mild forms of the disorder, which supports these genes ™ association with holoprosencephaly. Conversely, deletions of several candidate genes were present in individuals with no form of holoprosencephaly, which suggests deletion of these genes alone is not sufficient to cause the disorder. Researchers also identified a previously unreported abnormality associated with holoprosencephaly, an extra piece of DNA on one copy of chromosome 13, which was identified in two individuals with holoprosencephaly, one with a full form of the disorder and one with a mild form.

These results are exciting because they demonstrate how microarray testing allows us to broaden the clinical spectrum associated with various chromosome aberrations, said Lisa G. Shaffer, Ph.D., President and CEO of Signature Genomic Laboratories and senior author of the study. In the past, individuals were selected for study because they displayed the clinical features that were thought to be typical of a specific genetic disorder. Microarray analysis has allowed researchers to expand the boundaries of 'typical' for some of these disorders.

SOURCE Signature Genomic Laboratories