Mapping of a gene for alopecia with mental retardation syndrome (APMR3) on chromosome 18q11.2-q12.2.

Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan.
Annals of Human Genetics (Impact Factor: 2.22). 10/2007; 71(Pt 5):570-7. DOI: 10.1111/j.1469-1809.2007.00362.x
Source: PubMed

ABSTRACT Alopecia with mental retardation syndrome (APMR) is a rare autosomal recessive disorder characterized by total or partial absence of hair from the scalp and other parts of the body and associated with mental retardation. Previously, we have reported the mapping of two alopecia and mental retardation genes (APMR1 and APMR2) on human chromosome 3. In the present study, after excluding both of these loci through linkage analysis, a whole genome scan was performed by genotyping 396 polymorphic microsatellite markers located on 22 autosomes and the X and Y chromosomes. A disease locus was mapped to a 10.9 cM region, flanked by markers D18S866 and D18S811, on chromosome 18q11.2-q12.2. A maximum two-point LOD score of 3.03 at theta= 0.0 was obtained with marker D18S1102. Multipoint linkage analysis resulted in maximum LOD scores of 4.03 with several markers in the candidate region. According to the Rutgers combined linkage-physical map of the human genome (build 36) this region covers 12.17 Mb. DNA sequence analysis of nine candidate genes including DSC3, DSC1, DSG1, DSG4, DSG3, ZNF397, ZNF271, ZNF24 and ZNF396 did not reveal any sequence variants in the affected individuals of the family presented here.

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    ABSTRACT: Objective(s): Genetic analysis of two consanguineous Pakistani families with localized autosomal recessive hypotrichosis was performed with the goal to establish genotype-phenotype correlation. Materials and Methods: Genomic DNA extraction had been done from peripheral blood samples. Extracted DNA was then subjected to PCR (polymerase chain reaction) for amplification. Linkage analysis was performed using 8% polyacrylamide gel. Candidate gene was sequenced after gene linkage supported at highly polymorphic microsatellite markers of the diseased region. Results: Both families were initially tested for linkage to known genes, which were involved in human hereditary hypotrichosis, by genotyping Highly polymorphic microsatellite markers. Family B showed partial linkage at P2RY5 gene on chromosome 13q14.11-q21.32; hence, all exonic regions and their introns boundaries were subjected to DNA sequencing for any pathogenic mutation. Conclusion:Both families were tested for linkage by genotyping polymorphic microsatellite markers linked to known alopecia loci. Family A excluded all known diseased regions that is suggestive of some novel chromosomal disorder. However, sequencing of P2RY5 gene in family B showed no pathogenic mutation.
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