Craniometaphyseal dysplasia

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The GJA1 gene at 6q22.31 codes for the pro-peptide of Gap junction alpha-1 protein. This is processed to a hexadimer connexon that acts as a regulator of bladder capacity by sensitizing bladder muscles to cholinergic neural stimuli and causing them to contract and is critical to the recycling of potassium to the cochlear endolymph. It also is expressed in the heart.

Variations cause:

  • Oculodentodigital dysplasia (ODDD, OMIM:164200)
    • Abnormal facial appearance and variable involvement of the eyes, dentition, and fingers
      • Narrow, pinched nose with hypoplastic alae nasi
      • Prominent columella and thin anteverted nares
      • Narrow nasal bridge
      • Prominent epicanthic folds
    • Teeth are usually small and carious
    • Microphthalmia and microcornea
    • Syndactyly of the fourth and fifth fingers (syndactyly type III) classically
    • Occasional cardiac abnormalities
  • Autosomal recessive oculodentodigital dysplasia, (ODDD-AR, OMIM:257850)
  • Syndactyly 3 (SDTY3, OMIM:186100)
    • Persistence of the webbing between adjacent digits that is usually complete and bilateral between the fourth and fifth fingers
    • Occasionally distal phalanges are fused
    • Fifth finger is short with absent or rudimentary middle phalanx
    • Feet not affected186100
  • Hypoplastic left heart syndrome 1 (HLHS1, OMIM:241550)
    • Defective development of the aorta proximal to the entrance of the ductus arteriosus, and hypoplasia of the left ventricle and mitral valve
    • Patent ductus arteriosus and foramen ovale
  • Hallermann-Streiff syndrome (HSS, OMIM:234100)[1]
  • Atrioventricular septal defect 3 (AVSD3, OMIM:600309)
    • Common atrioventricular junction coexisting with deficient atrioventricular septation
      • Severe form has underdevelopment of the lower part of the atrial septum and the upper part of the ventricular septum
      • Less severe form is ostium primum atrial septal defect with separate atrioventricular valvar orifices despite a common junction.
  • Autosomal recessive craniometaphyseal dysplasia (CMDR, OMIM:218400)
    • Hyperostosis and sclerosis of the craniofacial bones
      • Asymmetry of the mandible
      • Sometimes secondary hearing loss and facial palsy
    • Abnormal modeling of the metaphyses