New insights into genotype-phenotype correlation for GLI3 mutations

Area of Science:

• Developmental Biology
• Human Genetics
• Medical Genetics

Background:

• GLI3 mutations lead to Greig cephalopolysyndactyly syndrome (GCPS) and Pallister-Hall syndrome (PHS).
• These syndromes present with distinct phenotypes, including limb malformations, craniofacial features, and central nervous system abnormalities.
• The bifunctional nature of GLI3 is crucial for normal development.

Purpose of the Study:

• To investigate the molecular and clinical spectrum of GLI3 mutations.
• To explore genotype-phenotype correlations in a large cohort of patients.
• To expand the understanding of GLI3-related malformations.

Main Methods:

• Molecular analysis of GLI3 gene mutations and deletions in 76 cases from 55 families.
• Clinical evaluation of patient phenotypes.
• In situ hybridization to study GLI3 expression during human development.

Main Results:

• Identified novel GLI3 mutations in 49 GCPS and 21 PHS cases, along with 6 deletions.
• Confirmed previously reported genotype-phenotype correlations.
• Observed a correlation between mutation location and corpus callosum abnormalities in GCPS.
• Documented fetal PHS cases, highlighting potential lethality and extending the malformation spectrum (e.g., agnathia, limb reduction defects).
• GLI3 shows early expression in key developmental tissues.

Conclusions:

• GLI3 mutations encompass a wide phenotypic spectrum, including GCPS and PHS.
• Genotype-phenotype correlations are significant, aiding in predicting clinical outcomes.
• Further research into GLI3's role in development is warranted to understand associated malformations.