Cryptic FMR1 mosaic deletion in a phenotypically normal mother of a boy with fragile X syndrome: case report

摘要: Increasing number of case reports mosaic mutations and deletions have better armed clinicians geneticists with more accurate focused prenatal diagnoses. Since mosaicism means a significant increase recurrence risk, detailed parental profiling is essential for risk assessments. We here describe clinically unaffected mother son who had fragile X syndrome (FXS) caused by large deletion that includes the entire FMR1. To assess regarding her second pregnancy, series genetic tests were conducted to establish this mother’s status. Routine single nucleotide polymorphism (SNP) array fluorescence in situ hybridisation (FISH) analyses detected two normal FMR1 copies blood. However, in-depth studies across deleted region revealed varying proportions somatic tissues: lowest blood, moderately higher skin, urine sediment menstrual discharge highest eyebrow. Further FISH analysis skin-derived fibroblasts confirmed 13%. our knowledge, first characterized female was an extensive investigation status provided valuable information reproduction choices. Our report may also alert cryptic heterogeneity should be carefully considered families children having defined ‘de novo’ mutations, avoid pregnancy identical abnormalities.