MORF4L1, encoding a chromatin remodeler, is mutated in a recognizable dysmorphic neurodevelopmental disorder.

Area of Science:

• Genetics
• Neurodevelopmental Biology
• Epigenetics

Background:

• Chromatin remodelers are crucial in neurodevelopment, often linked to dominant variants.
• Mortality Factor 4 Like 1 (MORF4L1) plays a role in chromatin organization and gene regulation.

Purpose of the Study:

• To investigate a novel autosomal recessive neurodevelopmental disorder associated with a MORF4L1 homozygous variant.
• To elucidate the functional impact of the MORF4L1 variant using zebrafish models.

Main Methods:

• Identified a consanguineous family with a homozygous MORF4L1 variant.
• Analyzed DNA methylation patterns in patients.
• Generated zebrafish models with MORF4L1 variants (patient and predicted loss-of-function).

Main Results:

• The family presented with a neurodevelopmental disorder and dysmorphic features linked to the MORF4L1 variant.
• Patients exhibited disrupted DNA methylation patterns.
• Zebrafish with biallelic MORF4L1 loss-of-function showed growth and craniofacial defects.
• Zebrafish carrying the specific patient variant (morf4l1^KI/KI) showed milder phenotypes, suggesting species-specific tolerance.

Conclusions:

• The study identifies a new autosomal recessive neurodevelopmental disorder caused by MORF4L1 variants.
• Functional modeling confirms a loss-of-function mechanism but highlights species-dependent differences in variant impact.
• Findings caution against over-reliance on animal models for variant classification without considering species-specific effects.