One Gene, Two Diseases
Take the reading one piece at a time. For each piece: read it once, underline the sentence that says what happens, then look up any word in the list. Tap a word to see its definition.
Piece 1 of 2
The IRF6 protein has two main parts: a DNA-binding domain (residues 7 to 115) that grabs DNA and a protein-binding domain that links to partner proteins (UniProt O14896). Researchers mapped variants from 549 families and recorded both the typo type and the disease. Truncating typos (nonsense/frameshift, e.g. R250X) spread across the whole gene cause the milder Van der Woude syndrome (lip pits, cleft lip/palate). Missense in the DNA-binding domain (e.g. R84C, R84H) cause the more severe popliteal pterygium syndrome (cleft plus skin webbing, genital and limb anomalies). Reported numbers: missense changes are significantly enriched in the DNA-binding domain (p around 0.0001) but not the protein-binding domain; truncating changes are spread evenly; about 67% of PPS families carry R84C or R84H.
Piece 2 of 2
You have two copies of IRF6, one from each parent; picture each as a worker carrying a load. Scenario A (one worker quits): a truncating typo makes one copy produce no usable protein, so one working copy does the job of two; if that is not enough, the job falls short (running on half-dose). Scenario B (one worker sabotages): a DNA-binding-domain missense makes one copy produce a full-length but broken protein that jams the good copy when they pair up to grab DNA, so function drops below half (poisoning the team). Kondo and colleagues proposed exactly this: VWS is consistent with simple loss of function, while severe PPS is consistent with a protein that actively interferes.
Reading the Research
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Now put it together: In one or two sentences, say what this whole reading is telling you about Mateo. Then go back to the lesson and fill in the guided notes.