| Institution: | 1. Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA;2. Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA
Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA;3. Rare Disease Institute, Children's National Hospital, Washington, DC, USA;4. Women's Health and Genetics, Laboratory Corporation of America, Burlington, North Carolina, USA;5. Valley Children's Healthcare, Madera, California, USA |
| Abstract: | Uniparental disomy (UPD) is the inheritance of both chromosomal homologs from one parent. Depending on the chromosome involved and the parental origin, UPD may result in phenotypic abnormalities due to aberrant methylation patterns or unmasking recessive conditions in isodisomic regions. UPD primarily originates from somatic rescue of a single meiotically-derived aneuploidy, most commonly a trisomy. Double UPD is exceedingly rare and triple UPD has not been previously described. Here, we report two unrelated clinical cases with UPD of multiple chromosomes; an 8-month-old male with maternal isodisomy of chromosome 7 and paternal isodisomy of chromosome 9, and a 4-week-old female with mixed paternal UPD for chromosomes 4, 10, and 14. These cases also demonstrate that although extremely rare, the detection of AOH on two or more chromosomes may warrant additional clinical and laboratory investigation such as methylation and STR marker analysis, especially when involving chromosomes known to be associated with imprinting disorders. |
