Occurrence of holoprosencephaly in chromosome 13 disorders cannot be explained by duplication/deficiency of a single locus.
Four cases of holoprosencephaly with duplication/deletion involving chromosome 13 are presented and additional cases are summarized from the literature. When examined as a series, the duplications (trisomy 13, trisomy 13pter----q14) and deletions (deletion 13q12----qter, deletion 13q31----qter, ring 13 with deletion 13q14----qter) exclude deletion or duplication of single chromosome 13 bands as the cause for holoprosencephaly. Increased dosage of the 13pter----q14 region relative to the 13q14----qter region as the cause is also ruled out by the duplication 13q21----qter cases reported in the literature. Altered timing of forebrain development, causing reversion to a more primitive embryonic and phylogenetic brain structure, is related to dosage imbalance of at least two chromosome 13 regions.
Wilson
G N
GN
Department of Medical Genetics, McGill University, Montreal, Quebec, Canada.
Dasouki
M
M
Barr
M
M
D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002874:Chromosome Mapping; D002882:Chromosomes, Human, Pair 13; D004027:Diencephalon / Q000002:abnormalities* / Q000473:pathology; D005260:Female; D005333:Fetus; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008636:Mesencephalon / Q000002:abnormalities* / Q000473:pathology; D011247:Pregnancy