Saturday, May 22, 2010
Franklin Hall B Level 4 (Philadelphia Marriott Downtown)
10:00 AM
Background: There is a strong genetic component to autism, but studies to date have demonstrated that the underlying genetic architecture is complex, with numerous genes potentially involved. One strategy for uncovering these genes is the use of large, extended families with multiple, distantly related, affected individuals. Our previous genome-wide linkage study identified a 4 centimorgan region (75-79 cM) on chromosome 12 that demonstrated significant linkage (HLOD = 4.51) across eleven extended multiplex families with only male affected individuals.
Objectives: Our goal is to comprehensively evaluate the chromosome 12 candidate region in order to identify the genetic abnormalities that underlie the strong autism linkage peak. We anticipate that this genetic abnormality will confer a moderate autism risk due to its presence in these large, extended families.
Methods: We are currently using both traditional Sanger sequencing and next generation, deep re-sequencing to identify potential causative variants. Sanger sequencing is used to identify variants in known and well annotated genes, while the Illumina Genome Analyzer II will be utilized to identify all potential variants across the entire approximately 4 Mb candidate region. Sanger sequencing was performed on 12 autistic individuals in 8 distinct families that define the region, as well as 10 control Caucasian individuals for 20 of the annotated genes in the minimal shared region (60,710,030-64,239,801 bp).
Results: Preliminary sequencing results failed to show variations of interest in 8 genes while the remaining 12 genes demonstrate one or more alterations that warrant further investigation: CAND1, CPSF6, FAM19A2, GNS, GRIP1, IRAK3, KIAA0984, MON2, RASSF3, TBK1, USP15, and XPOT. Variations in the genes of interest included both synonymous and nonsynonymous changes and alterations identified only in affected individuals. For example, 26 variants were found in MON2, 16 of which fell in intronic regions, 3 within the UTR regions and, for those that fell in exons, 3 caused missense changes and 4 were silent alterations. Two of the intronic alterations were only found in affected individuals. Deep re-sequencing using the Illumina GA II next-generation sequencing system in combination with SureSelect sequence capture (Agilent) of the minimal candidate region to completely catalogue variation in these families is currently underway.
Conclusions: Studies are ongoing to determine if any identified single nucleotide or copy number variations within the chromosome 12 region of interest plays a role in the etiology of ASD.
Objectives: Our goal is to comprehensively evaluate the chromosome 12 candidate region in order to identify the genetic abnormalities that underlie the strong autism linkage peak. We anticipate that this genetic abnormality will confer a moderate autism risk due to its presence in these large, extended families.
Methods: We are currently using both traditional Sanger sequencing and next generation, deep re-sequencing to identify potential causative variants. Sanger sequencing is used to identify variants in known and well annotated genes, while the Illumina Genome Analyzer II will be utilized to identify all potential variants across the entire approximately 4 Mb candidate region. Sanger sequencing was performed on 12 autistic individuals in 8 distinct families that define the region, as well as 10 control Caucasian individuals for 20 of the annotated genes in the minimal shared region (60,710,030-64,239,801 bp).
Results: Preliminary sequencing results failed to show variations of interest in 8 genes while the remaining 12 genes demonstrate one or more alterations that warrant further investigation: CAND1, CPSF6, FAM19A2, GNS, GRIP1, IRAK3, KIAA0984, MON2, RASSF3, TBK1, USP15, and XPOT. Variations in the genes of interest included both synonymous and nonsynonymous changes and alterations identified only in affected individuals. For example, 26 variants were found in MON2, 16 of which fell in intronic regions, 3 within the UTR regions and, for those that fell in exons, 3 caused missense changes and 4 were silent alterations. Two of the intronic alterations were only found in affected individuals. Deep re-sequencing using the Illumina GA II next-generation sequencing system in combination with SureSelect sequence capture (Agilent) of the minimal candidate region to completely catalogue variation in these families is currently underway.
Conclusions: Studies are ongoing to determine if any identified single nucleotide or copy number variations within the chromosome 12 region of interest plays a role in the etiology of ASD.