Genetic regulatory pathways of split-hand/foot malformation

Area of Science:

• Developmental biology
• Genetics
• Molecular biology

Background:

• Split-hand/foot malformation (SHFM) is a congenital limb malformation.
• SHFM is genetically heterogeneous, linked to mutations in genes like TP63, DLX5, DLX6, FGF8, FGFR1, WNT10B, and BHLHA9.
• Clinical presentations of SHFM caused by different gene mutations are often indistinguishable.

Purpose of the Study:

• To elucidate the shared underlying regulatory pathway disrupted in SHFM.
• To understand the molecular mechanisms leading to central hand and foot malformations.
• To investigate the role of signaling pathway dysregulation in SHFM pathogenesis.

Main Methods:

• Analysis of genetic mutations associated with SHFM.
• Investigating the role of Fibroblast Growth Factor 8 (FGF8) signaling in the apical ectodermal ridge (AER).
• Examining downstream gene expression and signaling pathway interactions (Fgf-Bmp-Msx, Wnt, SHH, HOX genes).

Main Results:

• Mutations in SHFM-associated genes lead to dysregulation of Fgf8 in the central AER.
• This dysregulation causes misexpression of downstream genes and failure of AER stratification, resulting in SHFM.
• Syndactyly and loss of digit identity are linked to disrupted signaling pathways, including Fgf-Bmp-Msx, Wnt, and SHH gradients.

Conclusions:

• SHFM pathogenesis involves the disruption of a common regulatory pathway affecting central hand and foot development.
• Dysregulation of Fgf8 in the AER and interconnected signaling pathways (Wnt, Bmp, Fgf) are central to SHFM.
• Understanding these pathways provides insights into limb development and malformation.