Marker X syndrome in an oriental family with probable transmission by a normal male

Rhoads, Frances A.; Oglesby, Allan; Mayer, Martha; Jacobs, Patricia A.

doi:10.1002/ajmg.1320120211

Cited by 56 publications

(24 citation statements)

References 19 publications

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“…These three had to be considered as brothers to both the probands in their families and so had to be counted twice. In order to calculate segregation ratios there were then 17 brothers, of whom 16 were studied cytogenetically, 12 were of normal intelligence, and five were mentally retarded. All of the five retarded brothers could be shown to carry the marker but none of those with normal IQ did.…”

Section: Segregation Ratios Within Familiesmentioning

confidence: 99%

“…In all, 16 maternal uncles were studied and, of 12 families who were actually shown to carry the fragile X(q27 3) themselves were considered. The segregation ratios were still disturbed, particularly for females.…”

Section: Segregation Ratios Within Familiesmentioning

confidence: 99%

“…There were two sets of brothers so a total of 12 families in which the fragile X was segregating had been ascertained in a completely unbiased manner. The pedigrees are shown in the figure.…”

mentioning

confidence: 99%

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Twelve families with fragile X(q27).

Webb¹,

Thake²,

Todd³

1986

Journal of Medical Genetics

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SUMMARY Through a community study of boys requiring special education for the severely mentally retarded, 12 families were ascertained in which the fragile X was found to be segregating. By assiduous follow up of these families, it was found that in only four of them could male transmission be ruled out from the grandparents' or great grandparents' generation and that the segregation ratios are disturbed.In the course of a population study of X linked mental retardation, 14 boys who were receiving special education at schools for the severely mentally subnormal were found to carry the fragile X(q27 3).'There were two sets of brothers so a total of 12 families in which the fragile X was segregating had been ascertained in a completely unbiased manner. The pedigrees are shown in the figure.In view of the reported unusual segregation pattern of the fragile X syndrome, in that one-third of the heterozygous females can be affected2 and that the disease can be transmitted through a normal male,-5 it was decided to follow up all family members of either sex, both affected and unaffected. In this way it was hoped to determine whether the unusual segregation and inheritance patterns found in the fragile X syndrome could be partially the result of bias in ascertainment of the families studied so far, or of partial follow up of affected and unaffected subjects in fragile X families. Methods

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Section: Segregation Ratios Within Familiesmentioning

confidence: 99%

Section: Segregation Ratios Within Familiesmentioning

confidence: 99%

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Twelve families with fragile X(q27).

Webb¹,

Thake²,

Todd³

1986

Journal of Medical Genetics

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“…USA 83 (1986) 1017 (9 Fragile-X Families. Pedigrees and cytogenetic data for the families 3, 4, and 13 have been published (8,14,15). The cytogenetic analysis in 13 other families was carried out as described (14,16 (4).…”

mentioning

confidence: 99%

“…Pedigrees and cytogenetic data for the families 3, 4, and 13 have been published (8,14,15). The cytogenetic analysis in 13 other families was carried out as described (14,16 (4). Second, unambiguous male transmitters were entered as affected, the status of cytogenetically normal adult women was considered as unknown, and a high penetrance value (0.9) was tested for younger females (under 18), since it is likely that most of the carriers are detected when cytogenetic analysis is carried out in this age category.…”

mentioning

confidence: 99%

Genetic analysis of the fragile-X mental retardation syndrome with two flanking polymorphic DNA markers.

Oberlé¹,

Heilig²,

Moisan³

et al. 1986

Proc. Natl. Acad. Sci. U.S.A.

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The fragile-X mental retardation syndrome, one of the most prevalent chromosome X-linked diseases (,1 of 2000 newborn males), is characterized by the presence in affected males and in a portion of carrier females of a fragile site at chromosome band Xq27. We have performed a linkage analysis in 16 families between the locus for the fragile-X syndrome, FRAXQ27, and two polymorphic DNA markers that correspond to the anonymous probe Stl4 and to the coagulation factor IX gene F9. Our results indicate that the order of loci is centromere-F9-FRAXQ27-Stl4-Xqter. The estimate of the recombination fraction for the linkage F9-FRAXQ27 is 0.12 (90% confidence limits: 0.044-0.225) and 0.10 for FRAX-Q27-Stl4 (90% confidence limits: 0.040-0.185). Recombination between Stl4 and F9 does not appear to be significantly different in normal and fragile-X families. The two flanking probes were used for diagnosis of the carrier state and for detection of transmission of the disease through phenotypically normal males. They should also allow first-trimester diagnosis with a reliability of about 98% in 40% of the families. Used in conjunction with the cytogenetic analysis, the segregation studies with both probes should improve the genetic counseling for the fragile-X syndrome and should be useful for the formal genetic analysis of this unique disease.

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