Genotype-Phenotype Correlation Of Individuals With Chromosome 8p23 Duplication Or Deletion Syndromes
Capstone Project Committee: Patrick Koty, PhD, FACMG, Pamela Reitnauer, MD, PhD, Randi Stewart, MS, CGC
The duplications and deletions of chromosome 8p23 are rare genetic conditions that display phenotypic continuums. Due to the variable expression and rarity of these disorders, in addition to the recently enhanced ability to detect subtle genetic imbalances, there is currently limited data regarding the frequent genotype-phenotype associations for each condition. To contribute to this limited medical knowledge, symptoms associated with four patients with either an 8p23 deletion or duplication, as identified and characterized by genomic studies, are described. The genotype-phenotype correlation was evaluated for each patient and compared to previously reported individuals with 8p23 duplication or deletion syndromes. The chromosome abnormalities of the four patients of this study were all found to be clinically significant. Two of the four patients were susceptible to a chromosome rearrangement, due to the involvement of two olfactory receptor gene clusters, REPD (REPeat Distal) and REPP (REPeat Proximal) that flank a 5 Mb region of 8p23.1. Additionally, the genomic variation in three patients involved at least one previously suggested candidate gene (GATA4, SOX7, TNKS, MCPH1, or MSRA) within the REPD and REPP interval. Although 8p23 duplication and deletion syndromes are rare and variable conditions, this study contributes to the limited amount of medical literature regarding the recurring genotype-phenotype correlations. Cytogenomic characterization of additional affected individuals will provide further clarification of the genotype-phenotype correlation of 8p23 duplication and deletion syndromes. Genetic counselors should evaluate and discuss the various implications of the condition (such as recurrence risks and testing options for family members or a future pregnancy) and provide resources to families.
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