# Positional programs in early murine facial development and their role in human facial shape variability

## TL;DR

This study explores how facial features develop in mice and how these processes relate to human facial diversity and birth defects.

## Contribution

The study links spatially defined mouse facial cell populations to human genetic variants affecting facial shape.

## Key findings

- Facial mesenchyme in mice shows molecular heterogeneity driven by positional programs.
- Genetic variants associated with human facial features are linked to specific cell populations and transcriptional signatures.
- The research provides a framework for understanding evolutionary and developmental mechanisms of facial variation.

## Abstract

The face is a complex, variable structure shaped by environmental and functional adaptations. In humans, the remarkable diversity of facial shapes underpins identity and mutual recognition. The developmental process from cranial neural crest cell migration to facial prominence fusion is conserved and essential for determining facial shape. However, the molecular and cellular underpinnings are not fully understood. We reconstruct facial development in the mouse model at the single-cell level, and show that the facial mesenchyme exhibits a remarkable molecular heterogeneity predominantly driven by positional programs. We then explore the role of these spatially defined murine mesenchymal populations in the extraordinary diversity of human facial shapes. By integrating molecular and spatial coordinates with human genome-wide association studies and genes linked to abnormal human facial shapes, we link genetic variants associated with facial features to individual cell populations and transcriptional signatures. This integrative approach provides a framework for exploring evolutionary processes behind facial variation and offers new insights into congenital facial syndromes.

Researchers mapped mouse facial development, revealing spatially distinct cell populations. Linking these to human genetics, they uncovered how facial features form and are inherited in a composite manner, shedding light on human facial diversity and birth defects.