Describe the main steps using positional cloning and linkage analysis to identify the locus associated with a simple Mendelian disorde

what question

Positional Cloning and Linkage Analysis (Mendelian Disorder)

layout

step,details

steps

Step 1: Pedigree Construction
Step 2: Genotyping
Step 3: Linkage Analysis
Step 4: Narrow Region
Step 5: Gene Identification
Step 6: Mutation Screening
Final Verification

Step 1:

Pedigree Construction

Step 2:

Genotyping

Step 3:

Linkage Analysis

Step 4:

Narrow Region

Step 5

Gene Identification

Step 6:

Mutation Screening

step 7

final verification

Step 1: Pedigree Construction

Track inheritance of disorder in affected families.

Step 2: Genotyping

Use polymorphic markers (e.g., microsatellites, SNPs).

Step 3: Linkage Analysis

Calculate recombination fractions; determine linkage with LOD scores.

Step 4: Narrow Region

Use fine mapping and additional markers to refine candidate region.

Step 5: Gene Identification

Clone genes in the region, compare to known sequences/databases.

Step 6: Mutation Screening

Sequence genes in affected individuals to find causative mutations.

Final Verification

Check segregation in family, bioinformatics analysis, possible functional test