| Fibrochondrogenesis | |
|---|---|
 | |
| Fibrochondrogenesis has an autosomal recessive pattern of inheritance. | |
| Specialty | Medical genetics  |
Fibrochondrogenesis is a rare[1]autosomalrecessive[2] form ofosteochondrodysplasia,[3] causing abnormal fibrous development ofcartilage and relatedtissues.[4]
It is a lethalrhizomelic (malformations which result in short, underdeveloped limbs) form ofdwarfism,[1] exhibiting bothskeletal dysplasia (malformations ofbone) andfibroblastic dysplasia (abnormal development offibroblasts, specializedcells that make upfibrous connective tissue, which plays a role in the formation of cellular structure and promotes healing of damagedtissues).[4][5][6] Death caused by complications of fibrochondrogenesis occurs ininfancy.[6]
Fibrochondrogenesis is acongenital disorder presenting several features andradiological findings, some which distinguish it from other osteochondrodysplasias.[7] These include: fibroblastic dysplasia andfibrosis ofchondrocytes (cells which form cartilage);[4][5] and flared, widenedlong bonemetaphyses (the portion of bone that grows during childhood).[6][8]
Other prominent features include dwarfism,[1] shortenedribs that have aconcave appearance,[6]micrognathism (severely underdevelopedjaw),[7]macrocephaly (enlarged head),[8]thoracichypoplasia (underdeveloped chest),[8] enlargedstomach,[8]platyspondyly (flattenedspine),[6] and the somewhat uncommon deformity ofbifidtongue (in which the tongue appears split, resembling that of areptile).[7]
The cause of platyspondyly in fibrochondrogenesis can be attributed in part to odd malformations and structural flaws found in thevertebral bodies of the spinal column in affected infants.[4][6]
Fibrochondrogenesis alters the normal function of chondrocytes, fibroblasts, metaphyseal cells and others associated with cartilage, bone andconnective tissues.[2][3][4] Overwhelmingdisorganization of cellular processes involved in the formation of cartilage and bone (ossification), in combination with fibroblastic degeneration of these cells, developmental errors and systemic skeletal malformations describes the severity of this lethal osteochondrodysplasia.[3][4][6][8]
Fibrochondrogenesis is inherited in an autosomal recessive pattern.[4] This means that the defectivegene responsible for the disorder is located on anautosome, and two copies of the gene — one copy inherited from each parent — are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder eachcarry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder. Currently, no specific geneticmutation has been established as the cause of fibrochondrogenesis.[9]
Omphalocele is a congenital feature where theabdominal wall has an opening, partially exposing theabdominal viscera (typically, theorgans of thegastrointestinal tract). Fibrochondrogenesis is believed to be related to omphaloceletype III, suggesting a possible genetic association between the two disorders.[10]
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Fibrochondrogenesis is quite rare.[1] A 1996 study fromSpain determined a national minimal prevalence for the disorder at 8 cases out of 1,158,067 live births.[11]
AUnited Arab Emirates (UAE)University report, from early 2003, evaluated the results of a 5-year study on the occurrence of a broad range of osteochondrodysplasias.[12] Out of 38,048 newborns inAl Ain, over the course of the study period, fibrochondrogenesis was found to be the most common of the recessive forms of osteochondrodysplasia, with a prevalence ratio of 1.05:10,000 births.[12]
While these results represented the most common occurrence within the group studied, they do not dispute the rarity of fibrochondrogenesis. The study also included the high rate ofconsanguinous marriages as a prevailing factor for these disorders, as well as the extremely low rate of diagnosis-relatedpregnancy terminations throughout the region.[12]
The fibrocartilaginous effects of fibrochondrogenesis on chondrocytes has shown potential as a means to producetherapeutic cellularbiomaterials viatissue engineering and manipulation ofstem cells,[13][14] specificallyhumanembryonicstem cells.[13]
Utilization of these cells as curative cartilage replacement materials on the cellular level has shown promise, with beneficial applications including the repair and healing of damagedkneemenisci andsynovial joints;temporomandibular joints, andvertebra.[13][14][15]