Convergent DNA Methylation Abnormalities at Bivalent Chromatin in Human Growth Disorders [methylation]

Overgrowth with Intellectual Disability (OGID) is characterized by generalized overgrowth, including a head circumference and/or height ≥ 2 standard deviations (s.d.) above the mean, accompanied by mild to moderate intellectual disability. Sotos Syndrome, the most common form of OGID, results from loss-of-function (LoF) mutations in NSD1, which encodes a histone methyltransferase. Another major OGID subtype, Tatton-Brown-Rahman syndrome, is caused by LoF mutations in DNMT3A, encoding a de novo DNA methyltransferase. In contrast, gain-of-function (GoF) mutations in DNMT3A cause Heyn-Sproul-Jackson syndrome, characterized by growth restriction and microcephaly. We hypothesize that NSD1 LoF and DNMT3A LoF mutations share a convergent DNA methylation signature that is distinct from the pattern seen in DNMT3A GoF mutations. To test this, we generated human embryonic stem cell lines carrying these growth syndrome-associated mutations in NSD1 and DNMT3A, profiled their DNA methylation patterns using the Illumina EPIC array, and analyzed both shared and unique methylation phenotypes. Genomic DNA from human embryonic stem cells genetically engineered to carry DNMT3A or NSD1 mutations associated with Tatton-Brown-Rahman syndrome, Heyn-Sproul-Jackson syndrome, or Sotos syndrome was bisulfite-converted and hybridized to the Illumina Infinium MethylationEPIC BeadChip.