Genomic coordinate (human 12:114,353,911 TBX5).
Polymorphs = 900 TBX5
Cytoband (human 12q24.21 TBX5).
Intraband %= 18.2%
Hyperbolic Umbilic Chromosome = 1,200 gene distribution.
OMIM’ genes @ 12q24.21 = 28
Here I present: “Holt-Oram Syndrome”, Victor McKusick, Mendelian Inheritance in Man’, 1966. (TBX5)
INTRODUCTION.
Holt-Oram syndrome is an autosomal dominant disorder characterized by abnormalities of the upper limbs and shoulder girdle, associated with a congenital heart lesion. The typical combination is considered to be a triphalangeal thumb with a secundum atrial septal defect (ASD), but there is a great range in the severity of both the heart and skeletal lesions.
The TBX5 gene encodes the T-box transcription factor-5 protein. This protein serves as a vital genetic master switch during early embryonic growth.
Heart Development: It directly controls the transcription networks that form the heart chambers and the electrical system coordinating heartbeats.
Limb Formation: It acts as the key initiator for the structural positioning and physical outgrowth of the forelimbs (arms and hands).
Clinical Relevance: Genetic mutations or deletions starting at this locus disrupt these pathways, causing Holt-Oram Syndrome. This condition is medically characterized by skeletal malformations in the upper limbs paired with congenital heart septal defects.
