A cytogenetic study of a population of mentally retarded males with special reference to the marker (X) syndrome

Jacobs, Patricia A.; Mayer, Martha; Matsuura, Janice; Rhoads, Frances A.; Yee, Stanley C.

doi:10.1007/bf00291533

Cited by 60 publications

(28 citation statements)

References 20 publications

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“…1). Such instances of transmission by normal males have been reported by others [Brgndum-Nielsen et al, 1981;Fryns and van den Berghe, 1982;Rhoads et al, 1982;Jacobs et al, 1983;Van Roy et al, 1983;Kahkonen et al, 19831, and this is unusual for an X-linked condition in which heterozygotes can also be affected. In Martin-Bell syndrome families where one member has fragile sites, mentally retarded males virtually always demonstrate the fragile site.…”

Section: Introductionmentioning

confidence: 67%

See 1 more Smart Citation

A premutation that generates a defect at crossing over explains the inheritance of fragile X mental retardation

Pembrey¹,

Winter²,

Davies³

et al. 1985

Am. J. Med. Genet.

121

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The view that the Martin-Bell syndrome (X-linked mental retardation with fragile site at Xq27/8) is inherited in a regular X-linked fashion is becoming untenable with the increasing number of reports of transmission through phenotypically normal males. Analysis of the published pedigrees containing such males shows that their heterozygous daughters are never mentally retarded, and have either no fragile site or very few indeed. By contrast, in the next generation, a third of the female heterozygotes are mentally subnormal with an average of 29% fragile sites. These data suggest a premutation that generates the definitive mutation only when transmitted by a female. We propose an inherited sub-microscopic chromosome rearrangement involving the Xq27/8 region that causes no ill effect per se, but generates a significant genetic imbalance when involved in a recombination event with the other X chromosome. This hypothesis explains many of the puzzling genetic aspects of the Martin-Bell syndrome, but it also complicates the interpretation of linkage analysis with genetic markers.

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Section: Introductionmentioning

confidence: 67%

“…There are eight reports giving a total of 15 phenotypically normal hemizygotes from eight families [Martin and Bell, 1943;Brdndum-Nielsen et al, 1981;Fryns and van den Berghe, 1982;Rhoads et al, 1982;Jacobs et al, 1983;Van Roy et al, 1983;Kahkonen et al, 19831. These 15 males had a total of 47 daughters.…”

Section: Analysis Of Published Pedigreesmentioning

confidence: 98%

A premutation that generates a defect at crossing over explains the inheritance of fragile X mental retardation

Pembrey¹,

Winter²,

Davies³

et al. 1985

Am. J. Med. Genet.

121

View full text Add to dashboard Cite

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“…While behavioural problems tended to decrease after the age of 5, the development delay became more and more obvious. Jacobs et al [13] and Rhoads et al [26] noted a decline in scores in a standard intelligence test with age in some of their patients. Chudley et al [5] demonstrated an age effect of IQ.…”

Section: Discussionmentioning

confidence: 97%

Developmental and behavioural disturbances in 13 boys with fragile X syndrome

Largo

Schinzel

1985

Eur J Pediatr

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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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“…chromosome was detected. Sutherland (1985d) Jacobs et al, 1983). In a survey, Tumer et al (1980) found that 77o of the girls from schools for the miidly retarded carried the fra (X) (q27).…”

Section: Expression Of Fragile Sites In Ot}ier Cell Typesmentioning

confidence: 99%

Segregation analysis of rare autosomal folate sensitive fragile sites

1993

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We have studied 12 families with rare autosomal folate sensitive fragile sites (RAFSFS). Of these, 9 were informative for segregtion analysis of fragile sites in order to assess differences in parental transmission. We identified 20 families with RAFSFS from the literature from 1985 to 1989; thirteen of these were informativ for segregation analysis. Segregation analysis confirmed that paternal fragile site transmission rates deviated significantly from the expected 50% for a Mendelian co‐dominant trait. Sex ratio comparisons showed a significant excess of transmitting females and a significnt excess of males among fragile site non‐carriers from the literature families. Comparison of the fragile site carriers with non‐carriers in the combined data showed a non‐significant excess of non‐carriers. We confirmed a deficiency of offspring expressing fragile sites when trnsmission was through fathers, suggesting gametic selection or the phenomenon of parental genomic imprinting. © 1993 Wiley‐Liss, Inc.

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A cytogenetic study of a population of mentally retarded males with special reference to the marker (X) syndrome

Cited by 60 publications

References 20 publications

A premutation that generates a defect at crossing over explains the inheritance of fragile X mental retardation

A premutation that generates a defect at crossing over explains the inheritance of fragile X mental retardation

Developmental and behavioural disturbances in 13 boys with fragile X syndrome

Segregation analysis of rare autosomal folate sensitive fragile sites

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