Ischiopatellar dysplasia | |
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Ischiopatellar dysplasia is inherited in an autosomal dominant manner [1] |
Ischiopatellar dysplasia is a rare autosomal dominant [2] disorder characterized by a hypoplasia of the patellae as well as other bone anomalies, especially concerning the pelvis and feet. [3] It is also known as small patella syndrome, with earlier synonyms being Scott-Taor syndrome, Coxo-podo-patellar syndrome, Patella aplasia, coxa vara, tarsal synostosis, Congenital coxa vara, patella aplasia and tarsal synostosis ischiocoxopodopatellar syndrome. [4]
Individuals affected by ischiopatellar dysplasia commonly have abnormalities of the patella and pelvic girdle, [5] such as absent or delayed patellar and ischial ossification as well as infra-acetabular axe-cut notches. [6] [7] [8] Patellae are typically absent or small in these individuals, when patellae are present they are small and laterally displaced or dislocated. [9] In addition, abnormalities in other parts of their skeleton and dysmorphic features are common in those affected. [10] [11] Other features that have been identified in patients with ischiopatellar dysplasia include foot anomalies, [12] specifically flat feet (pes planus), syndactylism of the toes, [13] short fourth and fifth toes, and a large gap between the first and second toes, [14] [15] femur anomalies, [16] cleft palate, [17] and craniofacial dysmorphisms. [18] [19]
Ischiopubic junction ossification can be absent, delayed, or abnormal. Other findings include hallux varus, brachymetatarsia affecting the fourth and fifth metatarsals, flat feet, and the presence of an elongated medial patellofemoral ligament. [20] [21] [22] Less common findings include micrognathia, cleft palate, frontal bossing and nose prominence. [23] Complications include infancy-onset recurrence of luxations, pain of the knee, impaired ability of running and riding bicycles, and late-onset gonarthrosis, [24] although it is not uncommon for some cases to be asymptomatic.
Ischiopatellar dysplasia is often considered a familial condition. [25] [26] [27] [28] Ischiopatellar dysplasia has been identified on region 5.6 cM on chromosome 17q22. Mutations in the TBX4 (T-box protein 4) gene, in chromosome 17, have been found to cause ischiopatellar dysplasia due to the essential role TBX4 plays in lower limb development since TBX4 is a transcription factor. [29]
Ischiopatellar dysplasia is usually identified through radiographic evidence since its characteristic changes are most notable in radiographic tests that indicate delayed bone age or absent ossification. [30] A full skeletal survey should be performed on any patient that has an absent or hypoplastic patellae since they could potentially have ischiopatellar dysplasia. Magnetic resonance imaging (MRI) is especially helpful in the diagnosis of ischiopatellar syndrome and is recommended when an individual affected by ischiopatellar dysplasia has a traumatic injury to the knee. [31]
Around 50-70 cases have been described in medical literature. [32] Diagnosis is made through genetic testing and radiography. [33]
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Ischiopatellar dysplasia is sometimes referred to as Scott-Taor syndrome after the researchers who first described ischiopatellar dysplasia as they recognized it in a family as an autosomal dominant disorder in 1979. [34] This finding was important as they were the first to note that it was a benign disorder that is separate from the more severe nail-patella syndrome. [35] Other common names for ischiopatellar syndrome are small patella syndrome (SPS), since the patellae are often small or absent in patients who have this syndrome, and coxo-podo-patellaire syndrome. [36] [37] [38]
Chondromalacia patellae is an inflammation of the underside of the patella and softening of the cartilage.
Patellar tendinitis, also known as jumper's knee, is an overuse injury of the tendon that straightens the knee. Symptoms include pain in the front of the knee. Typically the pain and tenderness is at the lower part of the kneecap, though the upper part may also be affected. Generally there is no pain when the person is at rest. Complications may include patellar tendon rupture.
Intraflagellar transport (IFT) is a bidirectional motility along axoneme microtubules that is essential for the formation (ciliogenesis) and maintenance of most eukaryotic cilia and flagella. It is thought to be required to build all cilia that assemble within a membrane projection from the cell surface. Plasmodium falciparum cilia and the sperm flagella of Drosophila are examples of cilia that assemble in the cytoplasm and do not require IFT. The process of IFT involves movement of large protein complexes called IFT particles or trains from the cell body to the ciliary tip and followed by their return to the cell body. The outward or anterograde movement is powered by kinesin-2 while the inward or retrograde movement is powered by cytoplasmic dynein 2/1b. The IFT particles are composed of about 20 proteins organized in two subcomplexes called complex A and B.
Ectrodactyly–ectodermal dysplasia–cleft syndrome, or EEC, and also referred to as EEC syndrome and split hand–split foot–ectodermal dysplasia–cleft syndrome is a rare form of ectodermal dysplasia, an autosomal dominant disorder inherited as a genetic trait. EEC is characterized by the triad of ectrodactyly, ectodermal dysplasia, and facial clefts. Other features noted in association with EEC include vesicoureteral reflux, recurrent urinary tract infections, obstruction of the nasolacrimal duct, decreased pigmentation of the hair and skin, missing or abnormal teeth, enamel hypoplasia, absent punctae in the lower eyelids, photophobia, occasional cognitive impairment and kidney anomalies, and conductive hearing loss.
Multiple epiphyseal dysplasia (MED), also known as Fairbank's disease, is a rare genetic disorder that affects the growing ends of bones. Long bones normally elongate by expansion of cartilage in the growth plate near their ends. As it expands outward from the growth plate, the cartilage mineralizes and hardens to become bone (ossification). In MED, this process is defective.
Raine syndrome (RNS), also called osteosclerotic bone dysplasia, is a rare autosomal recessive congenital disorder characterized by craniofacial anomalies including microcephaly, noticeably low set ears, osteosclerosis, a cleft palate, gum hyperplasia, a hypoplastic nose, and eye proptosis. It is considered to be a lethal disease, and usually leads to death within a few hours of birth. However, a recent report describes two studies in which children with Raine syndrome have lived to 8 and 11 years old, so it is currently proposed that there is a milder expression that the phenotype can take.
Hay–Wells syndrome is one of at least 150 known types of ectodermal dysplasia. These disorders affect tissues that arise from the ectodermal germ layer, such as skin, hair, and nails.
Laminopathies are a group of rare genetic disorders caused by mutations in genes encoding proteins of the nuclear lamina. Since the first reports of laminopathies in the late 1990s, increased research efforts have started to uncover the vital role of nuclear envelope proteins in cell and tissue integrity in animals. Laminopathies are a group of degenerative diseases, other disorders associated with inner nuclear membrane proteins are known as nuclear envelopathies.
Young–Simpson syndrome (YSS) is a rare congenital disorder with symptoms including hypothyroidism, heart defects, facial dysmorphism, cryptorchidism in males, hypotonia, intellectual disability, and postnatal growth retardation.
LIM homeobox transcription factor 1-beta, also known as LMX1B, is a protein which in humans is encoded by the LMX1B gene.
Tumor protein p63, typically referred to as p63, also known as transformation-related protein 63 is a protein that in humans is encoded by the TP63 gene.
Collagen alpha-2(IX) chain is a protein that in humans is encoded by the COL9A2 gene.
Putative ribosomal RNA methyltransferase 1 is an enzyme that in humans is encoded by the FTSJ1 gene.
Knee pain is pain in or around the knee.
Sensenbrenner syndrome is a rare multisystem disease first described by Judith A. Sensenbrenner in 1975. It is inherited in an autosomal recessive fashion, and a number of genes appear to be responsible. Three genes responsible have been identified: intraflagellar transport (IFT)122 (WDR10), IFT43—a subunit of the IFT complex A machinery of primary cilia, and WDR35
9q34 deletion syndrome is a rare genetic disorder. Terminal deletions of chromosome 9q34 have been associated with childhood hypotonia, a distinctive facial appearance and developmental disability. The facial features typically described include arched eyebrows, small head circumference, midface hypoplasia, prominent jaw and a pouting lower lip. Individuals with this disease may often have speech impediments, such as speech delays. Other characteristics of this disease include: epilepsy, congenital and urogenital defects, microcephaly, corpulence, and psychiatric disorders. From analysis of chromosomal breakpoints, as well as gene sequencing in suggestive cases, Kleefstra and colleagues identified EHMT1 as the causative gene. This gene is responsible for producing the protein histone methyltransferase which functions to alter histones. Ultimately, histone methyltransferases are important in deactivating certain genes, needed for proper growth and development. Moreover, a frameshift, missense, or nonsense error in the coding sequence of EHMT1 can result in this condition in an individual.
Microcephaly lymphoedema chorioretinal dysplasia also known as lymphedema microcephaly chorioretinopathy syndrome is a rare genetic condition associated with:
T-box transcription factor Tbx4 is a transcription factor that belongs to T-box gene family that is involved in the regulation of embryonic developmental processes. The transcription factor is encoded by the TBX4 gene located on human chromosome 17. Tbx4 is known mostly for its role in the development of the hindlimb, but it also plays a critical role in the formation of the umbilicus. Tbx4 has been shown to be expressed in the allantois, hindlimb, lung and proctodeum.
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Van Den Berghe Dequeker syndrome, also known as ulnar hypoplasia-split foot syndrome is a very rare congenital limb malformation syndrome which is characterized by severe ulnar hypoplasia, absence of the index to pinky finger in both hands, and split-foot.
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