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Severe nonspecific X-linked mental retardation caused by a proximally Xp located gene: intragenic heterogeneity or a new form of X-linked mental retardation?
Am J Med Genet. 1993 Apr 15; 46(2):172-5.AJ

Abstract

X-linked mental retardation (XLMR) can be subdivided into syndromic and nonsyndromic or nonspecific. Patients with non-syndromal XLMR show no characteristic manifestations, biochemical defects, or distinct fragile sites. Nevertheless, nonspecific XLMR seems to be heterogeneous. To determine the number and location of the genes responsible for XLMR, linkage studies in large pedigrees have to be performed. Here we report the data of linkage analysis in a large Brazilian family with 7 patients affected by a severe form of XLMR, with no other associated malformations. All the obligate carriers are normal. A close linkage without recombination (lod scores 1.95 and 3.25) was found between the disease locus and polymorphic DNA loci DXS255 (Xp11.22), DXS14 (Xp11.21). These results suggest that the gene responsible for the disease in this family maps in the Xp11-cent of the X chromosome. Positive lod scores in this region have also been reported for other XLMR genealogies, but with a much milder phenotype. The possibility of intragenic or locus heterogeneity is discussed.

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Authors+Show Affiliations

Passos-Bueno MR
Departamento de Biologia, Universidade de São Paulo, Brazil.
Byth BC
No affiliation info available
Rosenberg S
No affiliation info available
Takata RI
No affiliation info available
Bakker E
No affiliation info available
Beggs AH
No affiliation info available
Pavanello RC
No affiliation info available
Vainzof M
No affiliation info available
Davies KE
No affiliation info available
Zatz M
No affiliation info available

MeSH

AdolescentAdultChildChromosome MappingFemaleGenes, RecessiveGenetic LinkageGenetic MarkersHumansIntellectual DisabilityLod ScoreMaleMiddle AgedPedigreePhenotypeX Chromosome

Pub Type(s)

Case Reports
Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8484404

Citation

Passos-Bueno, M R., et al. "Severe Nonspecific X-linked Mental Retardation Caused By a Proximally Xp Located Gene: Intragenic Heterogeneity or a New Form of X-linked Mental Retardation?" American Journal of Medical Genetics, vol. 46, no. 2, 1993, pp. 172-5.
Passos-Bueno MR, Byth BC, Rosenberg S, et al. Severe nonspecific X-linked mental retardation caused by a proximally Xp located gene: intragenic heterogeneity or a new form of X-linked mental retardation? Am J Med Genet. 1993;46(2):172-5.
Passos-Bueno, M. R., Byth, B. C., Rosenberg, S., Takata, R. I., Bakker, E., Beggs, A. H., Pavanello, R. C., Vainzof, M., Davies, K. E., & Zatz, M. (1993). Severe nonspecific X-linked mental retardation caused by a proximally Xp located gene: intragenic heterogeneity or a new form of X-linked mental retardation? American Journal of Medical Genetics, 46(2), 172-5.
Passos-Bueno MR, et al. Severe Nonspecific X-linked Mental Retardation Caused By a Proximally Xp Located Gene: Intragenic Heterogeneity or a New Form of X-linked Mental Retardation. Am J Med Genet. 1993 Apr 15;46(2):172-5. PubMed PMID: 8484404.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Severe nonspecific X-linked mental retardation caused by a proximally Xp located gene: intragenic heterogeneity or a new form of X-linked mental retardation? AU - Passos-Bueno,M R, AU - Byth,B C, AU - Rosenberg,S, AU - Takata,R I, AU - Bakker,E, AU - Beggs,A H, AU - Pavanello,R C, AU - Vainzof,M, AU - Davies,K E, AU - Zatz,M, PY - 1993/4/15/pubmed PY - 1993/4/15/medline PY - 1993/4/15/entrez SP - 172 EP - 5 JF - American journal of medical genetics JO - Am J Med Genet VL - 46 IS - 2 N2 - X-linked mental retardation (XLMR) can be subdivided into syndromic and nonsyndromic or nonspecific. Patients with non-syndromal XLMR show no characteristic manifestations, biochemical defects, or distinct fragile sites. Nevertheless, nonspecific XLMR seems to be heterogeneous. To determine the number and location of the genes responsible for XLMR, linkage studies in large pedigrees have to be performed. Here we report the data of linkage analysis in a large Brazilian family with 7 patients affected by a severe form of XLMR, with no other associated malformations. All the obligate carriers are normal. A close linkage without recombination (lod scores 1.95 and 3.25) was found between the disease locus and polymorphic DNA loci DXS255 (Xp11.22), DXS14 (Xp11.21). These results suggest that the gene responsible for the disease in this family maps in the Xp11-cent of the X chromosome. Positive lod scores in this region have also been reported for other XLMR genealogies, but with a much milder phenotype. The possibility of intragenic or locus heterogeneity is discussed. SN - 0148-7299 UR - https://www.unboundmedicine.com/medline/citation/8484404/Severe_nonspecific_X_linked_mental_retardation_caused_by_a_proximally_Xp_located_gene:_intragenic_heterogeneity_or_a_new_form_of_X_linked_mental_retardation L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0148-7299&date=1993&volume=46&issue=2&spage=172 DB - PRIME DP - Unbound Medicine ER -