Chromatin-Related Disorders: Gene Attribution and Episignature Evidence

Gene discovery identified one major cause, rather than all cases

The primary abstract of Ng et al. reports exome discovery and follow-up sequencing that linked mutations in MLL2, the histone-methyltransferase gene named in that report, to Kabuki syndrome. The study included both newly arising and inherited variants in informative families. The result supports gene attribution in the examined cohorts; it does not certify every variant in that gene, explain every affected person or establish a single complete cellular mechanism. [1]

A second gene finding broadened the genetic explanation

Lederer et al. reported three Kabuki-syndrome individuals with de novo partial or complete deletions of KDM6A. The inspected primary abstract identifies KDM6A as a histone demethylase interacting with MLL2 and also reports skewed X-inactivation. This case series supports genetic heterogeneity; it does not show that methyltransferase and demethylase loss have identical effects at every chromatin site or isolate all consequences of a gene deletion. [2]

A mouse observation connects marks and phenotype within a model

The primary abstract of Bjornsson et al. describes a heterozygous Kmt2d mouse model with reduced dentate-gyrus H3K4me3 associated with reduced neurogenesis and hippocampal memory defects. These baseline observations connect a chromatin-related genotype, a histone mark and a phenotype in that model. They do not alone establish the corresponding causal sequence in every human patient. Pharmacologic results in the paper are outside this retained appraisal. [3]

DNA-methylation profiles add a different type of evidence

Sadikovic et al. report an assessment of genome-wide DNA-methylation profiles from peripheral-blood DNA in validation and clinical-referral cohorts containing rare neurodevelopmental disorders and controls. Profiles were compared with existing reference episignature classes. The inspected article reports concordant classifications for many validation samples and positive, negative or inconclusive outcomes among referred subjects. A reference-class resemblance is a measured downstream signature, rather than direct identification of every disrupted chromatin interaction. [4]

The inspected article reports limits from reference coverage, mosaicism, variant location and the existence of more than one signature for some genes. The article explicitly states that a negative result is not an absolute rule-out of pathogenicity. Conversely, a positive signature can guide attribution without establishing a complete mechanism, prognosis or treatment response. These limits should accompany claims about episignatures rather than treating the classifier as universally decisive. [4]

The linked correction’s indexed primary abstract was checked in this independent audit. It corrects the spelling of Michael A. Levy’s name and states that the original article was corrected. The notice describes no change to classifier data or scientific conclusions. This resolves the previously unknown correction scope at abstract depth; it is not a new validation of the classifier. Correction notice; original study.

Keep the evidence levels separate

Gene-discovery findings, preclinical mark-phenotype associations and blood methylation classification answer different questions. Together they motivate study of chromatin-related developmental disease, while leaving many variant-specific and tissue-specific mechanisms unresolved. The checked evidence does not supply a complete catalogue of chromatinopathies, a universal connection to cancer or an established therapy for these disorders. [1] [2] [3] [4]

Appraised primary evidence

1. Ng SB, Bigham AW, Buckingham KJ, Hannibal MC, McMillin MJ, Gildersleeve HI, Beck AE, Tabor HK, Cooper GM, Mefford HC, Lee C, Turner EH, Smith JD, Rieder MJ, Yoshiura K, Matsumoto N, Ohta T, Niikawa N, Nickerson DA, Bamshad MJ, Shendure J. (2010). Exome sequencing identifies MLL2 mutations as a cause of Kabuki syndrome. Nature genetics 42:790-793. Primary article and DOI

   Human Kabuki-syndrome probands and follow-up case/family comparisons. Selected discovery/follow-up cohorts, not all genetic causes or universal patient-level variant classification. Full Results and individual variant assessments not appraised. Previous focused appraisal access: Official primary abstract inspected for one or more explicitly abstract-bounded observations. Full main Results unavailable: public XML returned HTTP500 and PMC presented a browser challenge. No challenge/subscription bypass or full-text cache claimed. Primary source.

2. Lederer D, Grisart B, Digilio MC, Benoit V, Crespin M, Ghariani SC, Maystadt I, Dallapiccola B, Verellen-Dumoulin C. (2012). Deletion of KDM6A, a histone demethylase interacting with MLL2, in three patients with Kabuki syndrome. American journal of human genetics 90:119-124. Primary article and DOI

   Three reported Kabuki-syndrome individuals with partial/complete KDM6A deletions. Small reported case series; does not isolate every molecular mechanism, establish every KDM6A variant effect or define population prevalence. Previous focused appraisal access: Official primary abstract inspected for one or more explicitly abstract-bounded observations. Full main Results unavailable: public XML returned HTTP500 and PMC presented a browser challenge. No challenge/subscription bypass or full-text cache claimed. Primary source.

3. Bjornsson HT, Benjamin JS, Zhang L, Weissman J, Gerber EE, Chen YC, Vaurio RG, Potter MC, Hansen KD, Dietz HC. (2014). Histone deacetylase inhibition rescues structural and functional brain deficits in a mouse model of Kabuki syndrome. Science translational medicine 6:256ra135. Primary article and DOI

   Heterozygous Kmt2d mouse model, embryonic fibroblast reporter comparisons and dentate-gyrus/neurogenesis/memory observations. Full Results were not accessible. Pharmacologic intervention conclusions and procedures are not retained or appraised; model observations are not clinical efficacy evidence. Previous focused appraisal access: Official primary abstract inspected for one or more explicitly abstract-bounded observations. Full main Results unavailable: public XML returned HTTP500 and PMC presented a browser challenge. No challenge/subscription bypass or full-text cache claimed. Primary source.

4. Sadikovic B, Levy MA, Kerkhof J, Aref-Eshghi E, Schenkel L, Stuart A, McConkey H, Henneman P, Venema A, Schwartz CE, Stevenson RE, Skinner SA, DuPont BR, Fletcher RS, Balci TB, Siu VM, Granadillo JL, Masters J, Kadour M, Friez MJ, van Haelst MM, Mannens MMAM, Louie RJ, Lee JA, Tedder ML, Alders M. (2021). Clinical epigenomics: genome-wide DNA methylation analysis for the diagnosis of Mendelian disorders. Genetics in medicine : official journal of the American College of Medical Genetics 23:1065-1074. Primary article and DOI

   Archived and referred human peripheral-blood DNA: validation and clinical-testing cohorts. Cohorts include several rare neurodevelopmental disorders and controls, not all chromatin-related disorders or a population screening sample. Blood-specific reference data, classifier version and reference variant/gene coverage bound interpretation. Negative or inconclusive results are not absolute exclusion of pathogenicity; diagnostic yield is not general population sensitivity. No service endorsement or current clinical guideline claimed. The main article and indexed citation metadata identify correction DOI 10.1038/s41436-021-01130-z. The correction’s indexed primary abstract was checked on 12 October 2026: it describes correction of Michael A. Levy’s name and does not describe a scientific-results change. The correction body and classifier raw data were not independently reanalyzed. Previous focused appraisal access: Full primary article body retrieved. Named descriptive Results, figure captions and Discussion inspected for retained assertions. Supplementary protocols, raw data, operational procedures and treatment recommendations not appraised. Correction identity and name-only scope independently checked against the indexed primary correction abstract on 12 October 2026; this is abstract-level access, not an independent classifier validation. Linked correction.

5. Karayol R, Borroto MC, Haghshenas S, et al. (2024). MSL2 variants lead to a neurodevelopmental syndrome with lack of coordination, epilepsy, specific dysmorphisms, and a distinct episignature. American Journal of Human Genetics 111:1330–1351. DOI: 10.1016/j.ajhg.2024.05.001. Primary research.

   Independent update access: Consensus fetched primary abstract and Scite identity metadata inspected; Scite returned no readable body. No independent clinical validation or full-method appraisal. Primary source.

Earlier sections

Earlier broad sections were replaced by the focused review above. Retained fragment links lead here when their original section was withdrawn. Existing related documents may contain earlier unappraised prose.