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Lenski C, Abidi F, Meindl A, Gibson A, Platzer M, Frank Kooy R, Lubs HA, Stevenson RE, Ramser J, Schwartz CE. Novel truncating mutations in the polyglutamine tract binding protein 1 gene (PQBP1) cause Renpenning syndrome and X-linked mental retardation in another family with microcephaly. Am J Hum Genet 2004; 74:777-80. [PMID: 15024694 PMCID: PMC1181956 DOI: 10.1086/383205] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Affiliation(s)
- Claus Lenski
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Fatima Abidi
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Alfons Meindl
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Alice Gibson
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Matthias Platzer
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - R. Frank Kooy
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Herbert A. Lubs
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Roger E. Stevenson
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Juliane Ramser
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
| | - Charles E. Schwartz
- Department of Medical Genetics at the Ludwig-Maximilians-University, Munich; J.C. Self Research Institute, Greenwood Genetic Center, Greenwood, SC; Royal University Hospital, Saskatoon, Canada; Institute for Molecular Biotechnology, Jena, Germany; Department of Medical Genetics, University of Antwerp, Antwerp, Belgium; and Mailman Center for Child Development, University of Miami School of Medicine, Miami, FL
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2
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Johnson JP, Nelson R, Schwartz CE. A family with mental retardation, variable macrocephaly and macro-orchidism, and linkage to Xq12-q21. J Med Genet 1998; 35:1026-30. [PMID: 9863601 PMCID: PMC1051516 DOI: 10.1136/jmg.35.12.1026] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
A family with X linked inheritance of mental retardation (XLMR) is presented. There are 10 mentally retarded males and two affected females in two generations. There are four obligatory carriers, one of whom is described as "slow". Most affected males show macrocephaly and macro-orchidism, which are typical signs of the fragile X syndrome, but have been tested cytogenetically and by analysis of the FMR1 gene and do not have this syndrome. However, some normal males in the family also exhibit macro-orchidism and macrocephaly. Linkage analysis using markers derived from the X chromosome indicates that the causative gene in this family is located in the proximal long arm of the X chromosome, in the interval Xp11-q21. Maximum lod scores of 2.96 with no recombination were found at three loci in Xq13-q21: DXS1111, DXS566, and DXS986. Recombination was observed with DXS1002 (Xq21.31) and DXS991 (Xp11.2), loci separated by about 30 Mb. Although isolation of the gene in this family will be difficult because of the size of the region involved, the localisation should be helpful in investigating other similar families with XLMR, macrocephaly, and macro-orchidism not attributable to FMR1.
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Affiliation(s)
- J P Johnson
- Department of Medical Genetics, Shodair Hospital, Helena, MT 59604-5539, USA
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Stevenson RE, Arena JF, Ouzts E, Gibson A, Shokeir MH, Vnencak-Jones C, Lubs HA, May M, Schwartz CE. Renpenning syndrome maps to Xp11. Am J Hum Genet 1998; 62:1092-101. [PMID: 9545405 PMCID: PMC1377092 DOI: 10.1086/301835] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Mutations in genes on the X chromosome are believed to be responsible for the excess of males among individuals with mental retardation. Such genes are numerous, certainly >100, and cause both syndromal and nonsyndromal types of mental retardation. Clinical and molecular studies have been conducted on the Mennonite family with X-linked mental retardation (XLMR) reported, in 1962, by Renpenning et al. The clinical phenotype includes severe mental retardation, microcephaly, up-slanting palpebral fissures, small testes, and stature shorter than that of nonaffected males. Major malformations, neuromuscular abnormalities, and behavioral disturbances were not seen. Longevity is not impaired. Carrier females do not show heterozygote manifestations. The syndrome maps to Xp11.2-p11.4, with a maximum LOD score of 3.21 (recombination fraction 0) for markers between DXS1039 and DXS1068. Renpenning syndrome (also known as "MRXS8"; gene RENS1, MIM 309500) shares phenotypic manifestations with several other XLMR syndromes, notably the Sutherland-Haan syndrome. In none of these entities has the responsible gene been isolated; hence, the possibility that two or more of them may be allelic cannot be excluded at present.
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Murray J, Cuckle H, Taylor G, Hewison J. Screening for fragile X syndrome: information needs for health planners. J Med Screen 1997; 4:60-94. [PMID: 9275266 DOI: 10.1177/096914139700400204] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- J Murray
- Centre for Reproduction, Growth & Development, Research School of Medicine, University of Leeds, United Kingdom
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Abstract
Non-specific X linked mental retardation (MRX) is mental retardation in persons of normal physical appearance who have no recognisable features apart from a characteristic pedigree. Review of published reports shows that there is clinical variability in the degree of mental retardation within families and genetic heterogeneity, based on gene localisation, between families. We propose a classification based on genetic localisation and a set of minimal clinical features that should be recorded in the hope of identifying possible specific phenotypes.
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Affiliation(s)
- B Kerr
- Department of Medical Genetics, Prince of Wales Children's Hospital, Randwick, NSW, Australia
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Tommerup N. Induction of the fragile X on BrdU-substituted chromosomes with direct visualization of sister chromatid exchanges on banded chromosomes. Hum Genet 1989; 81:377-81. [PMID: 2703242 DOI: 10.1007/bf00283696] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
After incorporation of BrdU for one or more replication cycles, the fragile site at Xq27 [fra(X)] was induced by a late pulse with excess thymidine (dT), resulting in the simultaneous visualization of G bands and differentially stained sister chromatids. The degree of BrdU substitution (uni- vs bifilarly substituted DNA) did not affect the expression of hte fra(X). Without addition of dT, expression was the same in M1, M2, and M3 cells. With the addition of dT, expression was reduced in M1 cells and increased in M2 and M3 cells. One way to explain this fact would be an increased repair of the fragile site in M1 cells by illegitimate G:BrdU pairing under dCTP-deficient conditions. A preferential depletion of M3 cells, and to a lesser extent also M2 cells, could suggest a synergistic toxic effect of BrdU substitution and dCTP depletion. With this technique, sister chromatid exchanges (SCEs) could be directly localized at band level, facilitating a more detailed study of SCEs at the Xq27 fragile site.
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Affiliation(s)
- N Tommerup
- Department of Medical Genetics, John F. Kennedy Institute, Glostrup, Denmark
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Vieregge P, Froster-Iskenius U. Clinico-neurological investigations in the fra(X) form of mental retardation. J Neurol 1989; 236:85-92. [PMID: 2709058 DOI: 10.1007/bf00314402] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A clinical, neurological and electroencephalographic investigation was undertaken in 29 previously cytogenetically verified hemizygous males with the fra(X) form of mental retardation (age range 3.5 to 59 years); in addition, 6 heterozygous females were examined. All male patients displayed the known physical aspects of this syndrome together with associated abnormalities of the palate, skeleton, connective tissue and endocrine system. The most prominent neurological features were different forms of oculomotor disturbances, minor motor and pyramidal signs, incoordination, muscle hypotonia, gait and speech abnormalities. There was no increased frequency either in seizures or in epileptic EEG discharges. Some patients had a slowing of background activity in EEG. About 50% of all patients displayed autistic-like behaviour, short attention span and/or hyperactivity. In accordance with the literature, the findings indicate that there are no neurological, electroencephalographic or neuroradiological features which occur specifically in this syndrome. The need to differentiate the findings from those resulting from encephalopathic mechanisms during the gestational and perinatal period is stressed. A distinct typing of seizures and EEG changes is needed in each patient, before definite conclusions about an association of seizures and fra(X) syndrome are drawn. In view of the lack of correlation between IQ and the clinical-neurological measures, a more practical approach to quantifying the mental impairment is proposed.
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Affiliation(s)
- P Vieregge
- Klinik für Neurologie, Medizinische Universität zu Lübeck, Federal Republic of Germany
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Schwartz CE, Phelan MC, Pulliam LH, Wilkes G, Vanner LV, Albiez KL, Potts WA, Rogers RC, Schroer RJ, Saul RA. Fragile X syndrome: incidence, clinical and cytogenetic findings in the black and white populations of South Carolina. AMERICAN JOURNAL OF MEDICAL GENETICS 1988; 30:641-54. [PMID: 3177476 DOI: 10.1002/ajmg.1320300165] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Individuals in South Carolina with the Fragile X [fra(X)] or Martin-Bell syndrome have been ascertained by referral for evaluation of facial abnormalities, macroorchidism or mental deficit; by screening patients in residential and day programs for the mentally retarded; and by family follow up after an index case has been identified. Between 1982 and 1987, 100 positive fra(X) males were diagnosed. Of these, 35 were residents of residential facilities for the mentally retarded representing 2.5% of the population of institutionalized males. Another 23 were found in community day programs for the mentally retarded. Of these 58 cases, 28 (48%) were ascertained by screening for the craniofacial characteristics of the Martin-Bell syndrome, namely long face, midface hypoplasia, prominent forehead, large mandible and large simple pinnae. Although this screening procedure proved to be productive, it was found that the craniofacial traits of long face, midface hypoplasia, large jaw and simple pinnae were found less frequently in black fra(X) positive males and in prepubertal boys of both races.
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Thode A, Laing S, Partington MW, Turner G. Is there a fragile(X) negative Martin-Bell syndrome? AMERICAN JOURNAL OF MEDICAL GENETICS 1988; 30:459-71. [PMID: 3052069 DOI: 10.1002/ajmg.1320300149] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
During the course of the preventative screening program for the fra(X) syndrome, we identified 32 men with the phenotype but who were fra(X) negative. These were reviewed and none fitted the full criteria, so we were unable to confirm the existence of the fra(X) negative Martin-Bell syndrome. The literature and 4 families previously thought to have the fra(X) negative Martin-Bell syndrome were also reviewed. We were unable to make a concrete diagnosis of the fra(X) negative Martin-Bell syndrome.
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Affiliation(s)
- A Thode
- Department of Medical Genetics, Prince of Wales Children's Hospital, Randwick, New South Wales, Australia
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Prouty LA, Rogers RC, Stevenson RE, Dean JH, Palmer KK, Simensen RJ, Coston GN, Schwartz CE. Fragile X syndrome: growth, development, and intellectual function. AMERICAN JOURNAL OF MEDICAL GENETICS 1988; 30:123-42. [PMID: 3177438 DOI: 10.1002/ajmg.1320300111] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We collected data on growth, psychomotor development, speech and language development, and intellectual function on a cohort of 100 males with the fragile X chromosome and 95 carrier females. The data include information on prenatal growth (33 males), growth during the preadult years (32 males), psychomotor development during the first 2 years (25 males), speech and language development (15 males and 5 females), and intellectual function (93 males, 33 females, and 10 obligate carriers who were cytogenetically normal). Birth measurements appeared normal when plotted on the Usher/McLean curves of newborn infants (mean head circumference - OFC - at 40th centile, length at 60th centile and weight at 55th centile). Following birth, OFC rose above the 50th percentile and continued above average throughout the preadult years, whereas average length was above average for the first 5 years only and weight did not deviate from the normal mean. Psychomotor development lagged behind the norm from birth with affected males requiring nearly twice as long as expected to sit alone, walk unassisted, and say first words clearly. All males and females studied had significant language delay; all except one male had abnormalities of articulation. All on whom a clear voice sample was obtained had low voice pitch, and 80% had a hoarse or harsh quality of voice. Five males had word repetitions or perseverative speech during the preadult years. The mean IQ of the 93 males studied was 33 and regression analysis demonstrated a decrease in intellectual performance with age. Four fifths of the female carriers who expressed the fra(X) had intellectual performance in the mentally retarded range and showed similar decrease in performance with age. Obligate female carriers who did not express the fra(X) site had normal IQs (IQ 102 +/- 13.3).
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Affiliation(s)
- L A Prouty
- Greenwood Genetic Center, South Carolina 29646
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Thake A, Todd J, Webb T, Bundey S. Children with the fragile X chromosome at schools for the mildly mentally retarded. Dev Med Child Neurol 1987; 29:711-9. [PMID: 3691971 DOI: 10.1111/j.1469-8749.1987.tb08815.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
An investigation of children in schools for the moderately mentally handicapped in Coventry demonstrated that 29 of 259 children had a significant chromosomal abnormality. 10 of 155 boys (6 per cent) and 10 of 104 girls (10 per cent) had the fragile X syndrome. The clinical features which suggested this syndrome in males were IQ in the 50 to 70 range, head circumference greater than the 50th centile and post-pubertal testicular volume greater than the 50th centile. For both males and females, large ears were a useful sign. All children with fragile X had a carrier parent. The occurrence of mental retardation among sibs was one in two for brothers and one in four sisters. Considering all the males with fragile X syndrome resident in Coventry (this and previous studies), there were twice as many in schools for the moderately mentally handicapped as there were in schools for the severely mentally handicapped. There were as many females as males in the schools for the moderately mentally handicapped.
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Affiliation(s)
- A Thake
- Clinical Genetics Unit, Birmingham Maternity Hospital, Edgbaston
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12
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Bregman JD, Dykens E, Watson M, Ort SI, Leckman JF. Fragile-X syndrome: variability of phenotypic expression. J Am Acad Child Adolesc Psychiatry 1987; 26:463-71. [PMID: 3308830 DOI: 10.1097/00004583-198707000-00001] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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13
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Thake A, Todd J, Bundey S, Webb T. Is it possible to make a clinical diagnosis of the fragile X syndrome in a boy? Arch Dis Child 1985; 60:1001-7. [PMID: 4073931 PMCID: PMC1777630 DOI: 10.1136/adc.60.11.1001] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Clinical observations were made on a series of 156 boys with severe mental retardation, before cytogenetic results were known. The clinical features that helped to distinguish the 14 boys with the fragile X chromosome from those without were: head circumference over the 50th centile, postpubertal testicular volume over the 50th centile, and an IQ between 35 and 70. If the above clinical features were all present, then the chance of finding the fragile X chromosome was 1 in 3.6, whereas the chance of finding this abnormality in any boy with severe idiopathic mental retardation, regardless of his clinical features, was 1 in 9. Two boys with fragile X syndrome did not, however, possess any of the above clinical features. Moreover, some of the other retarded boys had clinical features of the syndrome, or an X linked pedigree, but lacked the chromosome abnormality.
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Atkin JF, Flaitz K, Patil S, Smith W. A new X-linked mental retardation syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1985; 21:697-705. [PMID: 4025397 DOI: 10.1002/ajmg.1320210411] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We have studied a three-generation family with 11 moderately to severely retarded males and three mildly retarded females (presumably manifesting carriers). The patients have a phenotype different from that of all other previously described types of X-linked MR (XLMR). These include short stature, macrocephaly, "coarse" facial appearance including prominent forehead and supraorbital ridges, hypertelorism, broad nasal tip with anteverted nostrils, and thick lips. All postpubertal males had macroorchidism (volume greater than 25 ml). Chromosomes were normal including fragile X analysis. X-ray findings of skull, spine, and hands were normal. The intellectually normal relatives do not resemble their affected relatives except for increased head size and testicular size. These findings suggest a new variant of XLMR different from fragile X-linked MR, the Coffin-Lowry syndrome, and other XLMR conditions.
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Gillberg C, Wahlström J. Chromosome abnormalities in infantile autism and other childhood psychoses: a population study of 66 cases. Dev Med Child Neurol 1985; 27:293-304. [PMID: 3160621 DOI: 10.1111/j.1469-8749.1985.tb04539.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Sixty-six psychotic children aged between two and 20 years, examined by the same child psychiatrist and diagnosed according to strict criteria as suffering from infantile autism, other psychoses and Asperger's syndrome, were examined with chromosomal cultures in folic-acid deficient medium. 47 per cent of the children showed major or minor chromosomal aberrations. The infantile autistic group comprised a total population of autistic children. The fra(X)(q27) marker was seen in 25 per cent of autistic boys. A subgroup of children with the fra(X)(q27) abnormality, infantile autism, psychomotor epilepsy and brainstem dysfunction was identified. Other chromosome markers and abnormalities occurring in several cases included long Y chromosomes, fra(X)(p22), fra(16)(q23) and fra(6)(q26). The results are discussed and correlated with certain clinical characteristics.
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Abstract
Developmental and behavioural aspects were studied in 13 boys aged 2.6-12.5 years from three families with the fragile X syndrome. The following observations were made. Moderate to severe retardation was present in all boys; non-verbal IQs ranged between 25 and 67 (mean 46 +/- 14); IQ and age were negatively correlated (P less than 0.01). Language development was grossly delayed in all boys; most had severe articulation problems. Imitative and symbolic play (e.g. doll play) were strikingly retarded as compared to abstract play (e.g. block design). Autistic features such as no use of eye contact, stereotyped movements and echolalia were found in 9/13 boys; the same number showed aggressive behaviour. General activity was reduced during the 1st year of life; most boys became very hyperactive during the second year; and short attention span and increased distractability were observed in all. Motor development was mildly delayed; all boys were clumsy and moderately hypotonic. The fragile X syndrome ought to be considered in retarded boys with a dissociated developmental pattern, in particular a striking delay in language and play development, and autistic features.
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Barbi G, Steinbach P, Vogel W. Nonrandom distribution of methotrexate-induced aberrations on human chromosomes. Detection of further folic acid sensitive fragile sites. Hum Genet 1984; 68:290-4. [PMID: 6239815 DOI: 10.1007/bf00292586] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Eleven folic acid sensitive fragile sites (3p14, 7p13, 7q31.1, 7q32, 9q32, 11p13, 14q23, 15q22, 16q23, Xp22.2, Xq22) were detected in one individual, eight of them previously unknown. These sites seem to bear each its specific sensitivity to folic acid deficiency. Six of the sites were observed simultaneously on both homologous chromosomes in at least one cell. Each of these 11 sites was also found in at least one among 12 individuals further examined. Some of these individuals showed six of these 11 sites. The fragile site 3p14 was detected in all individuals examined. The homologous sites 3p14 of one individual differed from each other in their frequency of lesions induced by methotrexate as well as fluorodeoxyuridine. This observation suggests that folic acid sensitivity is a property inherent in the chromatin of an individual chromosome at the site involved in fragility. This property seems to be responsible for the nonrandom fragility at that site and also for the individual sensitivity of each chromosomal site.
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Abstract
The present report summarizes the experience on the mar(X) syndrome in a total of 157 male patients (44 prepubertal and 113 postpubertal) ascertained through 83 index patients from 83 families under investigation. In one third of the families pedigree data were consistent with X-linked recessive inheritance. In the further two thirds of the families the presenting symptom was familial mental retardation with a mentally retarded mother, or mental subnormality with hyperkinetic behaviour in the male patient. No more than 60% of the adult males presented the typical clinical triad (mental retardation-long face-megalotestes). The most characteristic finding in the mar(X) boy is the psychological profile with severe hyperkinetism, hypersensitivity, handbiting and autistic features in some of them. In 4 of the 27 large mar(X) pedigrees strong evidence was present of a possible transmission of the mar(X) through normal males. The high incidence of mental subnormality in the female offspring of heterozygote carriers, and the relationship between mental status, phenotype, age and expression of the mar(X) in different culture conditions is discussed.
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Abstract
Folate metabolism and the effects of folic acid on chromosome stability were studied in four related patients with the fragile X syndrome. In three adults, uptake and subsequent utilization of folate compounds for conversion of deoxyuridylate to thymidylate by marrow cells and stimulated lymphocytes, and the affinity and maximal transport velocity of erythrocyte membrane carriers, were normal. Numbers of sister chromatid exchanges and double-stranded DNA breaks were comparable in cells from patients and control subjects, but both were increased after incubation in folate-deficient media. In vitro expression of the fragile site was strikingly reduced by oral folate therapy. It is concluded that the folate-sensitive chromosomal defect in this syndrome is limited to a specific site, Xq28, and there is no generalized tendency to frequent DNA breaks or recombination. Although expression was modified by folic acid treatment in the patients, no consistent abnormality of folate metabolism could be identified.
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Partington MW. The fragile X syndrome II: preliminary data on growth and development in males. AMERICAN JOURNAL OF MEDICAL GENETICS 1984; 17:175-94. [PMID: 6711594 DOI: 10.1002/ajmg.1320170111] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Growth data--stature, body weight, occipito-frontal circumference (OFC), ear length and mean testicular volume (MTV)--in 61 males with the fragile X syndrome are presented. Small increases in the mean OFC and ear length and large increases in the MTV were found. The overgrowth of the head was evident in childhood. The characteristic facial appearance was deemed to be present in 60% of the subjects and was recognizable in childhood. Macro-orchidism (MTV of greater than or equal to 30 ml) was present in 80% of the adults but none of the children. Five subjects had a cleft palate, 11 serious eye disorders (3 with congenital nystagmus), and 4 had torticollis and/or kyphosis. Limited information on development suggested that mental retardation was present from early life and was not progressive. Although 3 subjects were autistic (2 with self abuse) most were pleasant, even tempered and cooperative men and boys.
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Meryash DL, Cronk CE, Sachs B, Gerald PS. An anthropometric study of males with the fragile-X syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS 1984; 17:159-74. [PMID: 6711593 DOI: 10.1002/ajmg.1320170110] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Anthropometric methods were used to examine 18 males 18 to 69 years old with the Fragile-X syndrome. Thirteen of 15 subjects had macroorchidism. The average height of the individuals with the Fragile-X was less than that of published standards. Seventeen of the 18 subjects had absolute or relative macrocephaly, and two-thirds of the subjects were dolichocephalic. For the group as a whole, facial and ear lengths were increased, and facial breadth, hand length, and foot length were decreased. It is suggested that relationships between various measurements of an individual may be more important than any single measurements for conveying the characteristic appearance of an individual with the Fragile-X syndrome.
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Opitz JM, Sutherland GR. Conference report: International Workshop on the fragile X and X-linked mental retardation. AMERICAN JOURNAL OF MEDICAL GENETICS 1984; 17:5-94. [PMID: 6369987 DOI: 10.1002/ajmg.1320170103] [Citation(s) in RCA: 101] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Abstract
The results of a cytogenetic and segregation analysis of 110 pedigrees of the mar (X) syndrome are reported. The cytogenetic study indicated an inverse relationship between IQ and the mar(X) frequency in females but not in males. A small but significant effect of age on mar(X) frequency was observed in both males and females, but in females it was restricted to those of normal intelligence, retarded females showing no significant effect. Classical segregation analysis was performed using the program SEGRAN, analysing sexes separately. A 20% deficit of affected males was observed, the most plausible explanation for the majority of these cases being incomplete penetrance. Since this was an unexpected result, the data were scrutinized for possible biases; however, correction of these had little effect on the estimate. The penetrance of mental impairment in carrier females was estimated to be 30% and of mental impairment and/or mar(X) expression to be 56%. Thus 44% of carriers cannot be detected with our definition of affection. No evidence for sporadic cases among affected males was found. Complex segregation analysis was performed using the sex-linked version of POINTER, analysing sexes together. This was done in order to test the results from classical segregation analysis, to test for family resemblance and to estimate mutation rates. It was confirmed that there was a 20% deficit of affected males, that penetrance of mental impairment in females was approximately 30% and that there was no evidence for sporadic males. Thus all males with the gene appear to have received it from their carrier mothers and all mutations must occur in sperm. The mutation rate in sperm was estimated to be as high as 7.2 X 10(-4), implying that over one-half of random carrier females are fresh mutants. Our results have important implications for genetic counseling as they imply that all mothers of isolated affected males are carriers, that normal brothers of affected males have a 17% chance of carrying the gene and transmitting it to all their daughters, and that normal sisters of affected males have, at most, a 30% chance of being carriers. Since there are biases in the data due to the testing of particular individuals, these probabilities must be considered approximations until they are independently confirmed.
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de Arce MA, Law E, Masterson JG. Non-specific X-linked mental retardation with fragile X chromosome: somatic features, cytogenetic diagnosis and elements for genetic counselling. Ir J Med Sci 1983; 152:440-5. [PMID: 6668169 DOI: 10.1007/bf02958706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Vekemans M, Popovich B, Rosenblatt D, Monroe P. Chromosomal breakage in normal and fragile X subjects using low folate culture conditions. J Med Genet 1983; 20:404-7. [PMID: 6655666 PMCID: PMC1049167 DOI: 10.1136/jmg.20.6.404] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
To investigate whether the fragile X syndrome is associated with a generalised chromosomal instability, we compared the frequency and distribution of chromosomal breakage in lymphocytes grown in low folate medium from normal subjects and from patients with the syndrome. Although low folate conditions increased the rate of chromosome breakage, no difference in frequency or distribution of chromosomal breakage was found between the two groups. This suggests that the fragile X syndrome is not associated with a generalised chromosome instability expressed in folate deficient medium and assessed in terms of chromosomal breakage.
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Hunter AG, MacDonald J, Evans JA. Absence of the fragile X in a group of patients with idiopathic mental retardation. J Med Genet 1983; 20:314-5. [PMID: 6620334 PMCID: PMC1049131 DOI: 10.1136/jmg.20.4.314-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Howard-Peebles PN, Finley WH. Screening of mentally retarded males for macro-orchidism and the fragile X chromosome. AMERICAN JOURNAL OF MEDICAL GENETICS 1983; 15:631-5. [PMID: 6614051 DOI: 10.1002/ajmg.1320150414] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Four hundred forty-four male residents of a state mental retardation institution were screened for macro-orchidism. Twenty-six white males (8.3%) and two black males (1.5%) had marked macro-orchidism (greater than 34 ml). Seven of 17 whites tested for the fragile X were positive; the one black tested was negative. Thus, a minimum of 7/26 or 27% (whites) are fragile X positive indicating potential population variability, also evident from previous reports. Concurrent testing of institutionalized brother pairs indicated over half of the fragile X-positive males had a strong family history consistent with X-linked mental retardation.
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Kähkönen M, Leisti J, Wilska M, Varonen S. Marker X-associated mental retardation. A study of 150 retarded males. Clin Genet 1983; 23:397-404. [PMID: 6576874 DOI: 10.1111/j.1399-0004.1983.tb01973.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
One hundred and fifty male patients with mental retardation of unknown origin were studied cytogenetically. Six patients (4%) were marker X-positive. All these index cases were found in a subgroup of patients with no dysmorphic features, significant neurological findings or childhood psychosis. In this subgroup the frequency was 8.8%. One of the index cases had a family history suggestive of X-linked mental retardation, four had retarded 1st degree relatives and one had no family history of mental retardation.
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McDermott A, Walters R, Howell RT, Gardner A. Fragile X chromosome: clinical and cytogenetic studies on cases from seven families. J Med Genet 1983; 20:169-78. [PMID: 6876108 PMCID: PMC1049041 DOI: 10.1136/jmg.20.3.169] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Results of detailed clinical and cytogenetic studies on 13 mentally retarded males and two heterozygous females (one normal and one retarded) are reported. Reference is made to technical modifications to enhance the incidence of expression of the fragile X. The addition of excess methionine to the fibroblast cultures (final concentration of 115 mg/l medium TC 199) was found to be particularly valuable, increasing the incidence of expression up to four-fold, and enabling the demonstration of the fragile X in fibroblasts when it could not be demonstrated in blood cultures in at least one case. Studies on replication patterns of the X chromosomes in the two heterozygous females showed that the fragile X chromosome was genetically active in a significantly greater proportion of cells (74%) in the mentally retarded female, whereas the normal X was active in a similar proportion (72%) in the carrier with normal intelligence.
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31
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Silverman W, Lubin R, Jenkins EC, Brown WT. The strength of association between fragile (X) chromosome presence and mental retardation. Clin Genet 1983; 23:436-40. [PMID: 6684008 DOI: 10.1111/j.1399-0004.1983.tb01978.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In order to obtain a quantitative estimate of the degree of association between presence of fragile X chromosome (fra(X] and mental retardation (MR), existing data from nonretarded males were analyzed. Clearly, fra(X) occurs less frequently among nonretarded compared to MR males. However, incidence estimates for fra(X) based upon existing data hold open the possibility that there may be significant numbers of nonretarded males with fra(X). Additional analyses of data from families with a pattern of fra(X) linked MR showed: (a) the probability that nonretarded male offspring will have fra(X) is very small, and (b) the probability that MR male offspring will have fra(X) is very large. Thus, accurate prognostic decisions can be based upon prenatal diagnosis of fra(X) presence, especially in families with a pattern of fra(X) linked MR.
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Jacobs PA, Mayer M, Matsuura J, Rhoads F, Yee SC. A cytogenetic study of a population of mentally retarded males with special reference to the marker (X) syndrome. Hum Genet 1983; 63:139-48. [PMID: 6840758 DOI: 10.1007/bf00291533] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A cytogenetic survey of a population of 274 mentally retarded males on community placement is described. Thirty-five had an aneuploid chromosome constitution and five had the mar(X) syndrome. The range of clinical variation among the mar(X) probands and their affected relatives is described. Family studies were possible for four of the five mar(X) probands and in two families the mar(X) gene was apparently transmitted through a clinically normal male, suggesting that this type of male transmission may be a not uncommon phenomenon.
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33
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Jacky PB, Beek B, Sutherland GR. Fragile sites in chromosomes: possible model for the study of spontaneous chromosome breakage. Science 1983; 220:69-70. [PMID: 6828880 DOI: 10.1126/science.6828880] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The tissue culture condition that is required for the type of chromosome breakage seen at most fragile sites, namely, the absence of folic acid and thymidine in the medium, greatly enhanced micronucleus formation in proliferating lymphocyte cultures from normal individuals. This suggests that chromosome breakage at fragile sites and the apparently spontaneous damage that gives rise to micronuclei are controlled by the same mechanism.
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Fishburn J, Turner G, Daniel A, Brookwell R. The diagnosis and frequency of X-linked conditions in a cohort of moderately retarded males with affected brothers. AMERICAN JOURNAL OF MEDICAL GENETICS 1983; 14:713-24. [PMID: 6682625 DOI: 10.1002/ajmg.1320140413] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
An epidemiological study was carried out on the group of moderately retarded brothers (IQ, 30-55) identified by Turner and Turner [1974]. Of the original 58 sets of brothers, 54 sets (now 17 to 32 years old) were traced; another four sets (missed in the earlier survey) were added. Forty-five of the 58 pairs were diagnosed as having nonspecific X-linked mental retardation (MR) giving an overall frequency of 5.57 moderately retarded males/10,000 male births. In 12 of the 45 families, affected males had the fragile(X) and macroorchidism; six had macroorchidism alone, giving a frequency of 2.8 moderately retarded males with X-linked MR and macroorchidism +/- the fragile(X) per 10,000 males. Corresponding heterozygote frequencies are 7.34 and 3.65/10,000 females respectively. A new subgrouping of nonspecific X-linked mental retardation is described in six families: X-linked MR, macroorchidism without the fragile(X). Three other X-linked conditions were identified: in one family, the Coffin-Lowry syndrome, in another, Duchenne muscular dystrophy, and in two families X-linked MR and muscle atrophy. Half (56%) of the obligatory carriers of fra(X)-MR in this study were dull to mildly retarded. The mildly retarded heterozygotes had a significantly higher percentage of fra(X) expressing lymphocytes as compared to the intellectually normal heterozygotes. When the three types of nonspecific X-linked MR for which population frequencies were calculated were considered together, half of the obligatory carriers (46%) were dull or mildly retarded, thus confirming that this condition is a significant cause of mild intellectual handicap in females.
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Chudley AE, Knoll J, Gerrard JW, Shepel L, McGahey E, Anderson J. Fragile (X) X-linked mental retardation I: relationship between age and intelligence and the frequency of expression of fragil (X)(q28). AMERICAN JOURNAL OF MEDICAL GENETICS 1983; 14:699-712. [PMID: 6846402 DOI: 10.1002/ajmg.1320140412] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Members of eight Saskatchewan families with fragile (X) X-linked mental retardation were studied in an attempt to relate frequency to age and intelligence. The mean IQ of 37 affected men was 35 (range 10-66). The mean IQ of 32 carriers was 88 (range 57-119), and the mean IQ of 13 females who remain at risk for being carriers, have no affected sons, and who failed to demonstrate the fra(X) was 100 (range 78-126). We demonstrated a significant inverse relationship between age and frequency of the fra(X) in carriers and in affected males. However, we demonstrated a more highly significant inverse relationship between frequency of the fra(X) and IQ in carriers but to a lesser extent in affected males. Of 32 carriers, only 3 (9.4%) did not demonstrate the fra(X) after addition of 5-fluoro-2'-deoxyuridine (FUdR) to the folic acid and thymidine-reduced culture medium. From these data we would recommend that chromosome studies in individuals at risk for fra(X) X-linked mental retardation be carried out at the youngest age and that the addition of FUdR to culture medium is useful in carrier identification. It is clear that, in at least the carriers, a lower expression of the fra(X) is highly significantly correlated to higher intelligence.
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Renier WO, Smeets DF, Scheres JM, Hustinx TW, Hulsmans CF, Ophey CP, Bomers AJ, Gabreëls FJ. The Martin-Bell syndrome: a psychological, logopaedic and cytogenetic study of two affected brothers. JOURNAL OF MENTAL DEFICIENCY RESEARCH 1983; 27 (Pt 1):51-59. [PMID: 6864782 DOI: 10.1111/j.1365-2788.1983.tb00163.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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37
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Abstract
Eighty-one probands from an initial population of 223 school-aged retarded individuals were assessed by history, clinical examination and, where appropriate, cytogenetic analysis. In 51 individuals, the retardation occurred as an isolated event within the family, whereas 30 patients had a family history of retardation. In 39 of the isolated individuals, the retardation was either related to environmental factors or associated with a major neurological abnormality. The remaining 12 patients were phenotypically normal with no cytogenetic abnormality. Of the 30 probands from 15 families with a history of retardation, 3 families had X-linked syndromes. One, with 4 proband daughters, had the mar(X) syndrome and two families were considered to have the phenotypically similar syndrome but without demonstrating the mar(X). In an additional 5 families, the distribution and clinical features of the affected individuals were compatible with nonspecific X-linked mental retardation.
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38
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39
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40
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Howard-Peebles PN. Non-specific X-linked mental retardation: background, types, diagnosis and prevalence. JOURNAL OF MENTAL DEFICIENCY RESEARCH 1982; 26 (Pt 4):205-213. [PMID: 6763078 DOI: 10.1111/j.1365-2788.1982.tb00147.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This paper reviews non-specific X-linked mental retardation (X-linked MR), a heterogeneous group of X-linked recessive disorders which are controlled by one or more genes located on the X chromosome. Presently, there are at least three major subdivisions of X-linked MR. The IQ of affected males is variable. Carrier females usually have normal intelligence but some do show partial expression resulting in retardation. Genetics units can diagnose affected males utilizing pedigree analysis, clinical evaluation and cytogenetic testing (fragile X-linked MR type only). Projections indicate X-linked MR may be as common in males as Down syndrome and could account for 25% of the retarded male population.
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Brookwell R, Daniel A, Turner G, Fishburn J. The fragile X(q27) form of X-linked mental retardation: FUdR as an inducing agent for fra(X)(q27) expression in lymphocytes, fibroblasts, and amniocytes. AMERICAN JOURNAL OF MEDICAL GENETICS 1982; 13:139-48. [PMID: 6215863 DOI: 10.1002/ajmg.1320130206] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effect of FUdR on the expression of fra(X)(q27) was examined in lymphocytes and/or fibroblasts from 16 affected males and 5 carriers from 10 families; six different culture media were used: F10, 5% serum, pH 7.3(37 degrees C); medium 199, 5% serum, pH 7.6(37 degrees C); folate-free 199, 5% serum, pH 7.6(37 degrees C), and these three media with FUdR (0.05 micron). In lymphocytes there was no significant difference in the percentage of fra(X) expressing cells between any of the FUdR-containing media. The highest percentage of expressing cells seen in lymphocytes with FUdR was 56%. The average enhancement in males with FUdR in the 199 and folate-free 199 media was 30%. This relative enhancement with FUdR was very much higher in a few blood specimens delayed in transit and FUdR may prevent some of the false-negative results obtained from mailed specimens. FUdR did not induce the marker in four obligate carriers with previously negative results. The fibroblasts from affected males were grown in the six specific media for the last 48 hr. Two of the six media yielded reproducibly positive results. These were 199-FUdR and folate-free 199-FUdR with mean percentages of expressing cells of 12.8 +/- 7.1% and 11.3 +/- 6.1%, respectively. F10-FUdR, which contains thymidine, did not permit expression of the marker in fibroblasts and there was no difference in the percentage of fra(X) expression in 199-FUdR media with or without folate. It was concluded that FUdR shows promise as an agent to permit prenatal diagnosis of the condition and to enhance the detection of the marker in lymphocyte cultures.
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Nielsen KB, Tommerup N, Dyggve HV, Schou C. Macroorchidism and fragile X in mentally retarded males. Clinical, cytogenetic, and some hormonal investigations in mentally retarded males, including two with the fragile site at Xq28, fra(X)(q28). Hum Genet 1982; 61:113-7. [PMID: 6215327 DOI: 10.1007/bf00274199] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
One hundred and seventy eight males resident in an institution for the mentally retarded were screened clinically for the presence of macroorchidism, using the standard orchidometer. In this way 52 males with a testicular volume of 25 ml and over were found. Of these, 11 had pronounced macroorchidism (above 25 ml). All 52 males were examined cytogenetically for the fragile X. Two patients with pronounced macroorchidism showed this abnormality. Although the other nine patients with pronounced macroorchidism were reexamined with FUdR-addition to blood cultures, no further cases positive for the fragile X were found. Also, the thyroid function as well as the prolactin level in serum were investigated in all 52 males. No significant abnormalities were found. The high incidence of macroorchidism in mentally retarded males is underlined; however, it is suggested that the definition of macroorchidism should take into account several parameters.
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Steinbach P, Barbi G, Böller T. On the frequency of telomeric chromosomal changes induced by culture conditions suitable for fragile X expression. Hum Genet 1982; 61:160-2. [PMID: 7129442 DOI: 10.1007/bf00274209] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Under culture conditions suitable for the expression of the fragile site Xq27, "nonspecific" telomeric structural changes similar to the "specific" fra(X) formation occurred apparently on every chromosome arm. Significant differences between individuals seem to exist. The total frequency of nonspecific terminal lesions not located on the long arm of the X chromosome was 0.22 +/- 0.17 per cell in 37 cultures examined. If telomeric lesions on Xq occur in more than 0.7% of the cells from a single culture in males and more than 1.5% of the cells from a single culture in females, then this probably indicates a specific fra(X) expression. Lower percentages may be the result of nonspecific telomeric structural changes in q. These are expected to occur in the normal X as well and may, therefore, give rise to false positive diagnoses in the detection of hemi-, and hetero-, and perhaps also homozygous fra(X) carriers.
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Rhoads FA, Oglesby AC, Mayer M, Jacobs PA. Marker X syndrome in an oriental family with probable transmission by a normal male. AMERICAN JOURNAL OF MEDICAL GENETICS 1982; 12:205-17. [PMID: 7102725 DOI: 10.1002/ajmg.1320120211] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
We report an oriental family with sex-linked mental retardation, macroorchidism, and a marker or fragile site on the X chromosome--mar(X)(q28). The three affected males resemble clinically most previously reported affected Caucasians. The marker was present in four female 40-70 years old, including one with normal intelligence. Transmission of the disorder appears to have taken place through a clinically normal male to his grandson.
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Schmidt A. Fragile site Xq27 and mental retardation. Clinical and cytogenetic manifestation in heterozygotes and hemizygotes of five kindreds. Hum Genet 1982; 60:322-7. [PMID: 6955257 DOI: 10.1007/bf00569212] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Clinical and cytogenetic data of five kindreds with X-linked mental retardation and a methotrexate-inducible fragile site at the distal long arm of the X chromosome fra(X)(q27) are reported; comprising a total of 26 individuals studied cytogenetically, 10 hemizygotes, five obligate heterozygotes, seven facultative heterozygotes, and four normal males, i.e., fathers and brothers of affected hemizygotes. The heterozygotes in two of these sibships show partial phenotypic and/or mental manifestation. Two of them, who are obligate heterozygotes, expressed fra(X)(q27) in 23% and 16% of their metaphases at the ages of 27 and 53 years. In the obligate and facultative heterozygotes, who are mentally normal, the marker X chromosome could not be detected in lymphocyte cultures. We conclude from these findings that the occurrence of fra(X)(q27) might correlate with the phenotypic expression in heterozygotes rather than with the age of the individual.
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48
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Herbst DS, Dunn HG, Dill FJ, Kalousek DK, Krywaniuk LW. Further delineation of X-linked mental retardation. Hum Genet 1981; 58:366-72. [PMID: 6948768 DOI: 10.1007/bf00282817] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Chromosomal, clinical, and psychological data are presented on members of six families with X-linked mental retardation. Affected males in three of these families express the fra(X)(q28) marker, while the retarded males in the other three do not. Similar variable physical and psychological characteristics, such a lop ears, large testes, and perseverative speech, are present in affected males in all six families. Preliminary analysis of the psychological data also shows that males with and without marker expression cannot be differentiated with certainty. On this basis we suggest that there is a type of X-linked mental retardation with many phenotypic features of marker-X mental retardation but without expression of the X chromosome fragile site.
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50
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Mattei MG, Mattei JF, Vidal I, Giraud F. Expression in lymphocyte and fibroblast culture of the fragile X chromosome: a new technical approach. Hum Genet 1981; 59:166-9. [PMID: 7327576 DOI: 10.1007/bf00293069] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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