Hyperextensibility with normal elastic recoil is a feature of -
Ans. is 'a' i.e., Ehlers Danlos syndrome Ehlers - Panlos syndrome (EPS)Ehler's danlos syndrome comprise a clinically and genetically heterogenous group of disorder that result from some defect in the synthesis or structure of fibrillar collagen.The basic abnormality in Ehler9s Danlos syndrome (EDS) is some defect in the synthesis or structure of collagenBiosynthesis of collagen is a complex processIt involves numerous structural collagen genes or enzymes. Which are used in post transcriptional modification of collagen.Therefore it can be disturbed by no. of genetic errors that may affect any of the numerous genes or enzymes necessary for collagen synthesis.At the molecular level, a variety of defects, varying from mutations involving structural genes or collagens to those involving enzymes that are responsible for post transcriptional modification of mRNA have been detected.Such molecular heterogenicity result in expression of EDS as a clinically variable disorder with several patterns of inheritance.On the basis of clinical and molecular characteristics six variants of Ehler's Danlos syndrome have been identified.The common thread in all forms of EDS is some abnormality in the synthesis of collagen.Clinical featuresAs might be expected tissues rich in collagen such as skin, ligaments and joints are frequently involved.- Because the abnormal collagen fibre lacks adequate tensile strength, skin is hyper extensible and the joints are hypermobile.The skin is extraordinarily stretchable, extremely fragile and vulnerable to trauma.Minor injuries produce gaping defects and surgical repair or intervention is accomplished with great difficulty because of the lack of normal tensile strength.The defect in connective tissue may lead to serious internal complications which include:-Rupture of the colon and large arteriesOcular fragility with rupture of cornea and retinal detachmentDiaphragmatic herniaEDS typeGene defectInheritanceClinical findingsClassicalDefect in type V collagen Mutation in COL5A geneAutosomal dominantSkin and joint hypermo- bility, atrophic scars, Easy bruisingHypermobilityUnknownAutosomal dominantJoint hypermobility, pain, dislocationsVascularDefect in collagen type III Collagen III is abundant in Blood vessels and intestine severe defect of these organsAutosomal dominantsThe skin, arterial or uterine rupture, bru- ising, small joint hyperextensibilityKyphoscoliosisReduced level of lysyl hydroxylase essential for cross linking of collagen fibresAutosomal recessiveHypotonia, joint laxity, congenital scoliosis, ocular fragilityArthrochalasiaDefect in conversion of Procollagen to collagenResults from mutation in COL1A1and C0L1A2Autosomal dominantSevere joint hypermo- bility, skin changes mild, scoliosis, bruisingDermatospra- xiasMutation in the procollagen N peptidase gene.AutosomalRecessiveSevere skin fragility, cutis laxa, bruisingCutis laxaThe inelastic hyperextensible skin fails to resume its normal shape after stretching and hence appears pendulous.Therefore affected newborn infants appear "prematurely aged".The skin abnormality is most prominent around eye, face neck.Therefore patients with cutis laxa have characteristic facial features including an aged appearance with sagging jaws (blood hound appearance) a hooked nose with everted nostrils, a short columella, a long upper lip and everted lower eyelids. Hypermobility of the joint is not present.Pseudoxanthoma elasticumIt is a rare group of disorders affecting the elastic tissue. It primarily affects the dermis, retina, and cardiovascular system.The skin has characteristic "plucked chicken skin" appearance.- It tends to loose its elastic recoil when stretched.
Ehlers Danlos syndrome
Pseudoxanthoma elasticum
Cutis laxa
Scleroderma
Disorder of Metabolism & Connective Tissue