Kagami-Ogata syndrome in a patient with 46,XX,t(2;14)(q11.2;q32.2)mat disrupting MEG3.

Kagami-Ogata syndrome (KOS14) is a rare imprinting disorder characterized by a unique constellation of phenotypes including bell-shaped small thorax with coat-hanger appearance of the ribs. We encountered an African American female infant with KOS14 phenotype and 46,XX,t(2;14)(q11.2;q32.2)mat. After excluding upd(14)pat and an epimutation (hypermethylation) and a deletion affecting the maternally derived 14q32.2 imprinted region, we performed whole-genome sequencing, revealing that the translocation was generated between noncoding region at 2q11.2 and intron 6 of MEG3 at 14q32.2. Subsequent Sanger sequencing for the fusion points showed that the chromosomal fusion on the der(2) chromosome occurred between Chr2:102,193,994 (bp) and Chr14:101,314,628 (bp) in association with an insertion of 5-bp segment of unknown origin and that on the der(14) chromosome took place between Chr14:101,314,627 (bp) and Chr2:102,193,995 (bp) in association with an insertion of 1-bp segment of unknown origin (according to GRCh37/hg19). The results, together with the previous data in patients with KOS14, imply that the MEG3 disruption by 46,XX,t(2;14)(q11.2;q32.2)mat caused silencing of all MEGs including RTL1as and resultant excessive RTL1 expression, leading to the development of KOS14. To our knowledge, while Robertsonian translocations involving chromosome 14 have been reported in KOS14, this is the first case of KOS14 caused by a chromosomal translocation involving the 14q32.2 imprinted region.

Patients with unexplained mismatch repair deficiency are interested in updated genetic testing.

BACKGROUND: Individuals who have colorectal or endometrial cancers displaying loss of immunohistochemical staining of one or more mismatch repair proteins without an identifiable causative germline pathogenic variant have unexplained mismatch repair deficiency (UMMRD). Comprehensive germline genetic testing for Lynch syndrome (LS) includes sequencing and deletion/duplication analysis of MLH1, MSH2, MSH6, and PMS2, deletion analysis of EPCAM, and MSH2 inversion analysis. Updated genetic testing to include elements of comprehensive LS testing not previously completed could further clarify LS status in individuals with UMMRD, allowing for tailored screening guidelines for affected individuals and their family members. However, patient understanding of the potential impact of updated genetic testing for LS is unclear. This study aimed to evaluate the interest in and perceived impact of updated genetic testing among individuals with UMMRD at a tertiary academic center. METHODS: A survey evaluating interest in and perceived impact of updated genetic testing was mailed to 98 potential participants. Electronic health record review was completed for all individuals meeting eligibility criteria. Thirty-one individuals responded to the survey. RESULTS: Results indicate this population is highly interested in updated genetic testing with the perceived impact being primarily for family members to have appropriate genetic testing and screening. Electronic health record review indicates that clinicians have an evolving understanding of causes of UMMRD, representing a potential change in assessment of cancer risk. CONCLUSIONS: Updated risk assessment and genetic counseling with a discussion of the benefits and limitations of germline and somatic genetic testing, is essential as the understanding of UMMRD and genetic testing recommendations for this population evolve.