Ectodermal dysplasias: how many?
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Biomedical subjects
Publications and source records attributed to N Freire-Maia.
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This paper describes odontomicronychial dysplasia, a pure ectodermal dysplasia of the 2-3 subgroup of group A. It is characterised by precocious eruption and shedding of deciduous dentition, precocious eruption of secondary dentition with short, rhomboid roots, and short, thin, slow growing nails. This condition probably results from an autosomal recessive gene.
We present a casual review of 154 ectodermal dysplasias (EDs) as classified into 11 clinical subgroups. The number of EDs in each subgroup varies from one to 43. The numbers of conditions due to autosomal dominant, autosomal recessive, and X-linked genes are, respectively, 41, 52, and 8. In 53 conditions cause is unknown; 35 of them present some causal (genetic) suggestion.
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We report on a Brazilian woman, born to consanguineous (first cousin) parents (F = 1/16) and presenting cleft lip/palate, ectodermal dysplasia, interdigital webbing, and other malformations. Parental consanguinity and possible recurrence in sibs suggest autosomal recessive inheritance. The nosologic aspects with the Martinez syndrome and with the Zlotogora-Ogur syndrome are discussed.
The analysis of the data on 5677 children of 1063 couples from a fourth sample of consanguineous and nonconsanguineous marriages among whites and nonwhites living in the State of Minas Gerais, Brazil led to the following estimates: B (number of abnormal equivalents per gamete) around 0.5; A (morbidity in the non-inbred subsamples) 2-3 percent; B/A 13, 15, and 27 (this suggests that the morbidity disclosed by inbreeding may predominantly represent a mutational load); RR (relative risk) about 2 (this means that among the children of consanguineous marriages there is about double the frequency of abnormalities than in those with nonconsanguineous marriages); AR (attributable risk) for the whole sample about 7% (5% for nonwhites and 15% for whites). These last values show the amount that the frequency of abnormalities would decrease in the population if the risk factor (consanguineous marriages) would be eliminated. AR is higher in whites because the frequency of the risk factor is higher among whites.
An apparently hitherto undescribed pure ectodermal dysplasia of the tricho-onychic subgroup is described. Its cause is an autosomal dominant gene with complete penetrance and variable expressivity. Differential diagnosis considered 18 conditions belonging to the same subgroup, as well as Clouston syndrome. This report increases the number of conditions of the tricho-onychic subgroup to 19, and the total number of ectodermal dysplasias to 155.
Estimates of "relative risks" and "attributable risks" are presented for two Brazilian regions with the lowest (F = 0.00030) and the highest (F = 0.00395) inbreeding levels of the country, and for the whole country (F = 0.00088). The abolition of all consanguineous marriages (from second cousins up to and including uncle-niece/aunt-nephew marriages) in Brazil would eliminate only about 0.22, 3.05, and 0.65% of the "total damage," respectively. "Total damage" is defined as including abortions, miscarriages, stillbirths, infant-juvenile mortality (up to the age of 20 years), and anomalies in the survivors. The reduction of prenatal damage would be 0.11, 1.46, and 0.31%, and that of postnatal damage would be 0.49, 6.65, and 1.36%, respectively.
A short review is made on papers by Mendel, Wright, Haldane and Moshinsky, Cotterman, Malécot, Morton et al., and Khoury et al. The accompanying paper applies the two epidemiological approaches of this paper to the Brazilian populations.
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We report on 2 sisters and one brother with severe dental anomalies, trichodysplasia, onychodysplasia, and slight skin alterations. Four other relatives have only mild dental anomalies. Differential diagnosis includes 3 other ectodermal dysplasias: hypodontia and nail dysgenesis, dermoodontodysplasia, and trichodermodysplasia with dental alterations. Cause is unknown.
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This short review deals with the following problems: 1. frequencies of consanguineous marriages in Brazil; 2. their effects on precocious mortality (from abortions up to and including infant-juvenile mortality) and abnormalities among the survivors; 3. genetic counseling for consanguineous marriages; 4. reduction of the prenatal and post-natal damage in consequence of the abolition of the consanguineous marriages in Brazil.
We describe one daughter of a possibly distant consanguineous couple with infantile hypothyroidism, trichodysplasia, dental anomalies, dystrophic nails, skin alterations, otitis media, slight conductive hypoacusia, recurrent respiratory tract infections, and gastroenterologic problems. One of her two sisters presents dental anomalies and trichodysplasia, and had dry skin at birth. Similarity indexes are estimated for our patients in comparison with those described under the acronym ANOTHER syndrome. It is concluded that, in spite of the differences, it is possible that our two patients also present ANOTHER syndrome. The cause is unknown.
We report on two brothers (in a sibship of three) with partial aniridia, cerebellar ataxia, and moderate mental retardation, with normal G-banded chromosomes. Both present cerebellum hypoplasia; the younger also has congenital pulmonic stenosis. A review of the literature is presented. Cause is unknown, although the possibility of an autosomal recessive gene cannot be ruled out.
We describe a boy with bilateral lid agenesis and total keratinization of cornea and conjunctiva, macrostomia, psychomotor retardation, forehead hypertrichosis, ocular hypertelorism, thin lips, abnormal auricles and nose, skin alterations, and other findings. Differential diagnosis with ablepharon-macrostomia syndrome is presented. Cause is unknown.
A brother and sister, the offspring of first cousins, are described with retinitis pigmentosa, trichodysplasia (hypotrichosis and structural changes), dental anomalies, and onychodysplasia. This is a pure ectodermal dysplasia of the tricho-odonto-onychial subgroup, probably due to an autosomal recessive gene.