What Caused Mateo's Cleft?
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
Concordance means: given that one twin has a cleft, how often does the other twin also have one? Real concordance data for nonsyndromic clefts: identical (monozygotic) twins share nearly 100% of their DNA and are about 60% concordant, while fraternal (dizygotic) twins and ordinary siblings share about 50% of their DNA and are about 5 to 10% concordant. The reasoning: if a cleft were caused purely by genes, identical twins should be concordant close to 100% of the time; if it were caused purely by environment, sharing DNA should not matter at all.
Piece 2 of 2
Real environmental risk factors during pregnancy, with direction and rough effect size (an odds ratio near 1.0 means little change; above 1.0 means higher risk): maternal cigarette smoking, higher risk, OR about 1.3, the most robust environmental factor; valproic acid (an epilepsy medicine), higher risk especially cleft palate, a well-established teratogen; heavy or binge alcohol, higher risk roughly 1.5 to 4.7x and dose-dependent; folate (a B vitamin) deficiency, associated with higher risk with supplementation appearing protective in some studies, but the magnitude is debated so it is not overstated. Note that even the strongest single factor (smoking, OR about 1.3) is a small nudge, not a switch, and many mothers with none of these factors still have a child with a cleft, like Mateo's mother.
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.