Coupling deep phenotypic quantification with next-generation phenotyping for 192 individuals with germline...

Area of Science:

• Genetics
• Neurodevelopmental Disorders
• Rare Diseases

Background:

• Mendelian histonopathies are rare neurodevelopmental disorders (NDDs) stemming from germline variants in histone-encoding genes.
• Previous studies have focused on specific histonopathy syndromes, limiting a comprehensive understanding of the broader disease spectrum.

Purpose of the Study:

• To conduct an expansive pan-histonopathy interrogation, analyzing data from 192 affected individuals.
• To identify novel gene variants associated with histonopathies and explore phenotypic patterns, including craniofacial features.
• To develop an updated clinical survey to improve the identification and understanding of histonopathy phenotypes and associated risks, such as cancer.

Main Methods:

• Analysis of data from 192 individuals with histonopathies, including published and unpublished cases.
• Integration of clinician-reported phenotypic data with computational phenotyping of 2D facial photographs.
• Development and application of a standardized clinical survey for data collection.

Main Results:

• Identification of variants in genes not previously associated with disease (e.g., HIST1H2AL, H2AFZ, HIST1H3D, HIST3H3).
• Analysis revealed data gaps that currently confound the identification of distinct phenotypic patterns.
• The second known individual with a germline histonopathy and cancer diagnosis was identified; overall cancer incidence is 1%.

Conclusions:

• Histonopathy phenotypes evolve across the lifespan, requiring longitudinal assessment.
• Each identified individual significantly contributes to understanding these syndromes and improving patient care.
• Further translational research is crucial to clarify cancer predisposition in individuals with germline histonopathies.