Ectrodactyly
From Wikipedia, the free encyclopedia
| Ectrodactyly | |
|---|---|
| Classification and external resources | |
| ICD-10 | Q71.6 |
| ICD-9 | 755.4 |
| OMIM | 225300 |
| DiseasesDB | 32141 |
Contents |
[edit] Ectrodactyly
Ectrodactyly, sometimes referred to as the “Lobster-Claw Syndrome” [1] involves the deficiency or absence of one or more central digits of the hand or foot and is also known as split hand/split foot malformation (SHFM). [2] The hands and feet of people with ectrodactyly are often described as "claw-like" and may include only the thumb and one finger (usually either the little finger, ring finger, or a syndactyly of the two) with similar abnormalities of the feet. [3]
[edit] Genetics
A large number of human gene defects can cause ectrodactyly. The most common mode of inheritance is autosomal-dominant with reduced penetrance, while autosomal-recessive and X-linked forms occur more rarely. [4] Ectrodactyly can also be caused by deletions, translocations, and inversions in chromosome 7 (7q). [5] The deletions in 7q can result in a contiguous gene syndrome that includes growth impairment, microcephaly, craniofacial manifestations, hernias, hearing loss, and mental retardation [5]. Translocations in 7q do not have as many abnormalities but are generally associated with most hearing loss cases. [5] This is why most cases of ectrodactyly are generally accompanied by another abnormality or linked to another syndrome (ex. EEC, LMS, ECP [6]). Detailed studies of a number of mouse models for ectrodactyly have also revealed that a failure to maintain median apical ectodermal ridge (AER) signalling can be the main pathogenic mechanism in triggering this abnormality. [4] A number of factors make the identification of the genetic defects underlying human ectrodactyly a complicated process: the limited number of families linked to each split hand/food malformation (SHFM) locus, the large number of morphogens involved in limb development, the complex interactions between these morphogens, the involvement of modifier genes, and the presumed involvement of multiple gene or long-range regulatory elements in some cases of ectrodactyly. [4] In the clinical setting these genetic characteristics can become problematic, making predictions of carrier status and severity of the disease impossible to predict. [7]
[edit] Hearing Loss
As mentioned in the Genetics section, ectrodactyly can be caused by various mutations to 7q. When 7q is mutated by deletion or translocation ectrodactyly can sometimes be associated with hearing loss. [5] Ectrodactyly, or Split hand/split foot malformation (SHFM) type 1 is the only form of split hand/foot malformation associated with sensorineural hearing loss. [5] A study was performed in 2001 by the JC Self Research Institute, a division of the Greenwood Genetic Center, to test the split hand/split foot malformation with hearing loss as it pertained to being genetically passed through two unrelated families. In the larger family, various split foot malformations were found in 6 of 11 gene carriers, and mild-to-moderate sensorineural hearing loss in four. [20] In the second family, split foot was observed in 3 of 4 gene carriers, and sensorineural deafness was present in 3. [20] These malformations appear to be very dominant genetic traits. Recently SHFM type 1 has been shown to result from Mondini dysplasia in a boy with a deletion in chromosome 7, but it was the only case reported to share Mondini dysplasia with ectrodactyly. [5] The article discusses that although hearing loss can be related to ectrodactyly, there is not a set genetic mutation or specific additional disease that can be correlated as a direct cause for hearing loss. It is merely evident that they exist together. [5] This would also appear to be the case for some other incidences of ectrodactyly that sporadically occur in association with other various diseases.
[edit] Treatment
Some of those suffering from ectrodactyly seek out a way to treat their disease or help make dealing with it easier. Management of the milder forms of ectrodactyly usually consist of custom-molded shoes and orthoses with an accommodative spacer to fill the defect berated by deformity. [8] For severe deformities, treatment consists of several surgical operations. These include closing wedge osteotomies, syndactylization, desyndactylization, removal of osseous segments, and correction hammertoe and hallux valgus deformities. [8] In one case study from The Journal of Foot and Ankle Surgery, a 5-year-old female was diagnosed with pedal ectrodactyly (or type IV bilateral ectrodactyly) and could not fit into conventional shoes, nor could she walk without the aid of orthoses and custom-molded shoes. [8] She was treated with a double surgery approach, which included the removal of the second cuneiform bone. [8] As a result the two “toes” were able to be pushed together and healed side by side, causing the girl to be able to fit into conventional footwear and walk without the aid of specially molded shoes. For many, surgical intervention is not needed so they choose to use prosthetic limbs (link) to disguise the abnormality from the public eye. [9]
[edit] Functionality
The functional utility of the malformed limbs is discussed In The British Medical Journal, Vol. 2. [10] The affected persons can perform work that requires skillful manipulation, regardless of their handicap. The article says, “The needlework of some of the females is good; the handwriting of most is excellent. One individual is a boot maker, two others drive cabs, none finding difficulty in clothing themselves, and most do so with extraordinary rapidity, even to the lacing of boots....It is said of one that he is able in this way to lift pins from the floor with his feet.” Those with ectrodactyly are contributing members of society with their own jobs and careers [11]; many choose to have families and raise children [11]. In most daily tasks the health condition appears to have a small effect on their functionality.
[edit] Ectrodactyly in Species other than Humans
Ectrodactyly is not only a genetic characteristic in humans, but can also occur in frogs and toads [12], mice [13], salamanders [14], cows [4], chickens [4], rabbits [4], marmosets [4], cats and dogs [15], and even West Indian manatees [4]. The following examples are studies showing the natural occurrence of ectrodactyly in animals, without the disease being reproduced and tested in a laboratory. In all three examples we see how rare the actual occurrence of ectrodactyly is.
[edit] Wood Frog
The Department of Biological Sciences at the University of Alberta in Edmonton, Alberta performed a study to estimate deformity levels in Wood Frogs in areas of relatively low disturbance. [12] After roughly 22, 733 individuals were examined during field studies, it was found that only 49 Wood Frogs had the ectrodactyly deformity. [12]
[edit] Salamanders
In a study performed by the Department of Forestry and Natural Resources at Purdue University, approximately 2000 salamanders (687 adults and 1259 larvae) were captured from a large wetland complex and evaluated for malformations. [14] Among the 687 adults, 54 (7.9%) were malformed. Of these 54 adults, 46 (85%) had missing (ectrodactyly), extra (polyphalangy) or dwarfed digits (brachydactyly). [14] Among the 1259 larvae, 102 were malformed, with 94 (92%) of the malformations involving ectrodactyly, polyphalangy, and brachydactyly. [14] Results showed few differences in the frequency of malformations among life-history changes, suggesting that malformed larvae do not suffer substantially higher mortality than their adult conspecifics. [14]
[edit] Cats and Dogs
In a “Journal of Heredity” published by the Oxford Journals a study was performed to test allele frequencies in domestic cats. Among the 265 cats observed, there were 101 males and 164 females. Only one cat was recorded to have the ectrodactyly abnormality [16], illustrating this rare and unique disease. According to M.P. Ferreira, a case of ectrodactyly was found in a two month old male mixed Terrier dog, [17] In another study, Carrig and co-workers also reported a series of 14 dogs [18] with this abnormality proving that although ectrodactyly is an uncommon occurrence for dogs, it is not entirely unheard of.
[edit] Human Genetic Disorders Associated with Ectrodactyly
Ectrodactyly is frequently seen with other congenital anomalies, or other birth defects, and may be caused by genetic factors or by exposure of the embryo to environmental factors. [19] Syndromes in which ectrodactyly is associated with other abnormalities can occur when two or more genes are affected by a chromosomal rearrangement. [19] Disorders associated with ectrodactyly include Ectrodactyly-Ectodermal Dysplasia-Clefting (EEC) syndrome, which is closely correlated to the ADULT syndrome and Limb-mammary (LMS) syndrome, Ectrodactyly-Cleft Palate (ECP) syndrome, Ectrodactyly-Ectodermal Dysplasia-Macular Dystrophy (EEM) syndrome, Ectrodactyly-Fibular Aplasia/Hypoplasia (EFA) syndrome, and Ectrodactyly-Polydactyly. Note that there are more than 50 syndromes and associations distinguished in the London Dysmorphology Database [6], so the complete list is not written above.
[edit] Famous People with Ectrodactyly
- Bree Walker [11] -Once a popular television anchor woman in Los Angeles, she has appeared in the sitcom “Nip/Tuck” as an inspirational character who battles her disease and counsels another family who have children with ectrodactyly.
-Grady Stiles Sr. and Grady Stiles Jr.
-Vadoma Tribe in Africa
-Mikhail Tal, chess World Champion
[edit] References
[1]< "Medical Mystery: Ectrodactyly". ABC News. 2007-01-27.>
[2] <Moerman P, Fryns JP. "Ectodermal dysplasia, Rapp-Hodgkin type in a mother and severe ectrodactyly-ectodermal dysplasia-clefting syndrome (EEC) in her child". American Journal of Medical Genetics Part A. 63.3 (1998): 479–81.>
[3] <Peterson-Falzone, Sally J.; Mary A. Hardin-Jones, Michael P. Karnell, Betty Jane McWilliams (2001). Cleft Palate Speech. Mosby. ISBN 9780815131533.>
[4] <Pascal, H.G. et al. “Pathogenesis of split-hand/split-foot malformation.” Human Molecular Genetics 12.1 (2003): R51-R60.>
[5] <Wieland I, et al. “Refinement of the deletion in 7q21.3 associated with split hand/foot malformation type 1 and Mundane dysplasia.” Journal of Medical Genetics Electronic Letter (2004): 1-4>
[6] <Winter, R.M. and Baraitser, M. (1987) The London Dysmorphology Database. J. Med. Genet., 24, 509–510.>
[7] <Scherer, Stephen et al. “Human Chromosome 7: DNA Sequence and Biology.” Science 300.5620 (2003): 767-772>
[8] <Santini, Stefano et al. “Pedal ectrodactyly: A case report with a new surgical management.” The Journal of Foot and Ankle Surgery 41. 5 (2002): 320-327.>
[9] <Thami, GP., S Kauai. “Split hand-foot malformation: a congenital central limb ray deficiency.” Images in Medicine 48.3 (2002): 209-210.>
[10] <“The Inheritance of Deformities.” The British Medical Journal 2. 2481 (1908): 168-169.
[11] <http://abcnews.go.com/Health/story?id=2832319&page=1>
[12] <Eaton, Brian R., et al. “Deformity Levels in Wild Populations of the Wood Frog (Rana sylvatica) in Three Ecoregions of Western Canada.” Journal of Herpetology, 38.2 (2004): 283-287.>
[13] <Manson, Jeanne, Michael L. Dourson and Carl C. Smith. “Effects of Cytosine Arabinoside on In vivo and In vitro Mouse limb Development.” In Vitro 13.7 (1977): 434-442>
[14] <Williams, Rod, David Bos, David Gopurenko and Andrew DeWoody. “Amphibian Malformations and Inbreeding.” Biology Letters: Population Genetics. Biol. Lett. doi:10.1098/rsbl.2008.0233. Purdue University. 22 Nov. 2009> <http://web.ics.purdue.edu/~dewoody/documents/Williamsetal.Malformations_BiolLetters.pfd>
[15]
[16] <Davis, Brian, Barry Davis. “Allele frequencies in a cat population in Budapest”. Journal of Heredity. 68 (1977): 31-34.> [17] <FERREIRA, M.P. et al. Ectrodactilia em cão: relato de caso. Arq. Bras. Med. Vet. Zootec. [online]. 59.4 (2007): 910-913.> [18] <Carrig CB, Wortman JA, Morris EL et al: Ectrodactyly (split-hand deformity) in the dog. Vet Radiol 22: 123, 1981> [19] <Pascal, H.G., Hans van Bokhoven and Han G. Brunner. “Pathogenesis of split-hand/split-foot malformation.” Human Molecular Genetics 12.1 (2003): R51–R60.> [20] <Tackles-Horne D., et al. “Split hand/split food malformation with hearing loss: first report of families linked to the SHFM1 locus in 7q21.” Clinical Genetics 59.1 (2001): 28-36.>
 Ectrodactyly on the right hand of a one-month old child |
 Ectrodactyly on the right foot of a one-month old child |
 Ectrodactyly on both feet of a one-year old child |
 Ectrodactyly on the hand of a one-year old child |
[edit] External links
- Online 'Mendelian Inheritance in Man' (OMIM) 183600
- Online 'Mendelian Inheritance in Man' (OMIM) 183800
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