LCH patients and their parents undergo collection of saliva or buccal mucosa samples for genetic mutational analysis. Germline DNA from saliva or buccal brushing will be sequenced, genotyped, and analyzed.

Undergo saliva or buccal mucosa collection

Will re-sequence SMAD6 among LCH case-parent trios to characterize the association between SMAD6 inherited genetic effects and LCH susceptibility using targeted next-generation sequencing. We will also analyze de novo single-nucleotide variants (SNVs), copy-number variants (CNVs), and insertions/deletions(INDELs) obtained through SMAD6 sequence data generated from the biologic samples of the CCRN/PEC LCH case-parent trios.

Will use the maximum number of LCH case-parent trios enrolled utilizing the CCRN/PEC with viable biologic samples to conduct genome-wide SNP genotyping. This methodology will identify new genes and pathways associated with LCH susceptibility. We will also determine the prevalence of novel de novo mutations associated with LCH in these case-parent trios. This will provide a systematic assessment of the underlying genetic makeup of LCH in a large sample of families.

Genetic ancestry will be determined using germline genome-wide SNP array data generated from CCRN/PEC LCH cases in Aim 2. In parallel, we will determine patient somatic mutational profiles using a custom, targeted 91-gene panel. We will then conduct a genome-wide admixture-mapping scan to identify LCH-related loci that are associated with specific LCH somatic mutational profiles.

The analysis of data generated in this outcome measure will be primarily descriptive in nature. the objective will be to characterize LCH case-parent trios based on demographic, epidemiologic, and clinical characteristics. Findings from primary outcome measures findings will be validated and will assess if the frequency of validated inherited genetic variants differs by these characteristics.