1 - Cytogenetics Laboratory, CGC Genetics – Oporto, Portugal
2 - Department of Medical Genetics, Hospital Dona Estefânia – CHLC EPE, Lisbon, Portugal
Americam College of Medical Genetics Annual Clinical Genetics Meeting 2016. Tampa, Florida, USA
Koolen-De Vries Syndrome (KDVS) is a rare disorder caused by haploinsufficiency of KANSL1 gene, either by heterozygous mutation of KANSL1 or microdeletion on chromosome 17q21.31. Major clinical features include delayed psychomotor development, hypotonia and characteristic facial features. To this day, all individuals reported with KDVS were identified as having the syndrome as a result of a de novo microdeletion/mutation event. Even though it is not known whether KDVS affects fertility, it is considered that parent-to-offspring transmission can take place in an autosomal dominant manner. However, no individual with KDVS has been reported to have had children of their own.We report two novel patients with KDVS, in which the microdeletion pattern associated with this syndrome was vertically transmitted, from mother to son. To our knowledge this is the first case report of a parental transmission of KDVS. Array-based comparative genomic hybridization (aCGH) was performed on an Affymetrix platform, Cytoscan 750K. Data analysis was performed on ChAS Software, Affymetrix (NCBI_hg19 reference). Proband was tested at age 7 by aCGH which revealed a 477 Kb interstitial microdeletion at 17q21.31 (Chr17:43,710,150-44,187,492) and KDVS diagnosis was concluded. The mother of the proband was studied at age 32, after the son diagnosis, by aCGH and a 503 Kb interstitial microdeletion at 17q21.31 (Chr17:43,710,150-44,213,434) was found and diagnosis was also concluded as KDVS. Both microdeletions resulted in complete loss of 9 genes, of which KANSL1 and MAPT are known to be associated to human disease. Other protein and non-protein genes are unknown or have not been related to human disease and, therefore, it is unclear to which extent they are involved in the clinical phenotype. Future studies will be focused on testing further members of the family to investigate the origin of the microdeletion pattern.
Palavras Chave: Koolen-de Vries syndrome; 17q21.31; Parental transmition
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