Synonym: Urban-Rifkin-Davis Syndrome (URDS)
Gene: LTBP4 (latent transforming growth factor-beta binding protein 4)
Chromosome: 19q13.2
Pathophysiology: LTBP-4 is a structural component of connective tissue microfibrils and helps to regulate transforming growth factor beta (TGF-beta) locally. Absence of LTBP-4 results in increased activity of transforming growth factor-beta on fibroblasts and defective assembly of elastic fibers.
Inheritance: autosomal recessive, with affected individuals homozygous or complex heterozygous
Clinical features:
(1) postnatal growth delay
(2) skin laxity (cutis laxa)
(3) respiratory insufficiency secondary to cystic and atelectatic changes in the lung parenchyma, tracheomalacia and diaphragmatic hernia
(4) gastrointestinal malformations (stenosis, increased tortuosity, distention, and/or diverticulosis)
(5) craniofacial abnormalities (microretrognathia, receding forehead, flattened midface, wide fontanalles)
(6) urinary tract malformations (hydronephrosis, diverticulosis)
(7) cardiovascular abnormalities (cardiomyopathy, pulmonary artery stenosis or patent foramen ovale)
(8) joint laxity
(9) low muscle tone
