Clue 1: Orient yourself
Does one drop fill the cup?
Use the labels and the picture's left-to-right, near-to-far, or before-and-after order. Name only what you can point to.
The question
Why do most kids with a cleft have no single thing to blame?
Why it matters: Cleft care connects diagnosis, feeding, speech, hearing, and family support. A weak classification can send a team toward the wrong problem or make an important need easy to miss. Today you practice the professional reasoning behind that work: Most isolated clefts reflect many small genetic and environmental influences crossing a developmental threshold.
On your WebXam
Interpreting twin concordance and odds ratios to identify a multifactorial cause
For life
One result can have many causes; the outcome alone never tells you which.
Principle: Many roads, one ending
Five principles we return to
Having it is not using it
Same instructions, different switches
Same look, different cause
Change one thing and watch
Boss or doorman?
Decides the result or only allows it
Held down, not gone
Remove the brake and it returns
Many roads, one ending
One result can begin many ways
Try the everyday version first
Many small drops can fill a threshold cup
A threshold cup stays below its fill line until enough drops add up. No single small drop must be large, but their combined amount can cross the line.
Do not jump to the biology yet. Treat the picture as a small system. Track its parts, follow one change at a time, and keep more than one explanation open until the picture supplies a way to separate them.
Clue 2: Trace one change
Could different combinations reach the same line?
Follow one object, stage, or path. Point to the first place where the situation changes instead of jumping to the ending.
Clue 3: Keep the cause open
Can you identify one guilty drop after the cup overflows?
List more than one explanation that still fits. Name the extra observation that would help you separate those possibilities.
Now inspect the illustration
Work from the visible evidence. A useful answer names the part of the picture that supports it and leaves unknown causes open.
- 1Does one drop fill the cup?
- 2Could different combinations reach the same line?
- 3Can you identify one guilty drop after the cup overflows?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: Why do most kids with a cleft have no single thing to blame?
You can complete today's required check without opening the technical details below.
Ready for the real names? Optional tier 2
Technical rules and limits
Rule 1: Many small influences can add together.
Rule 2: Different combinations can cross the same threshold.
Rule 3: Risk is not certainty and association is not blame.
Where the analogy stops: Biologic risk is not a literal liquid sum. The model simplifies interacting influences into a threshold idea.
Carry the previous idea forward
Epidemiology describes patterns in groups; it does not identify the cause of one child's cleft.
Today's technical takeaway
Most isolated clefts reflect many small genetic and environmental influences crossing a developmental threshold.
Now map the same rules onto biology
Use the threshold model for an isolated cleft
Small drops
Small genetic variants and environmental exposures
Fill line
Developmental threshold for disrupted fusion
Overflow
A cleft forms during the developmental window
The model explains shared risk without inventing a single cause that the evidence cannot support.
Mateo's case file: evidence supplied in this lesson
D09-E1
Mateo has no clear syndrome pattern or single-gene family pattern.
Why it matters: A simple one-gene explanation is not supported by the case.
D09-E2
Research finds many genetic regions associated with common nonsyndromic clefts.
Why it matters: Multiple small genetic influences can contribute.
D09-E3
Smoking and some other pregnancy exposures are associated with higher risk, but no exposure in Mateo's case proves causation.
Why it matters: Environmental factors change risk without assigning blame for an individual case.
Make the clinical decision
You are answering Mateo's parents when they ask, 'What did we do to cause this?'
Your answer must be accurate, clear, and free of blame.
AExplain multifactorial risk and that no single cause can be identified in this case
BName one exposure as the cause
CSay genes always determine the outcome
Choose the explanation and use all three evidence IDs to set the limits of the claim.
Evidence required
D09-E1 + D09-E2 + D09-E3 Claim ceiling
You may explain multifactorial risk. You may not claim a specific exposure or variant caused Mateo's cleft.Go deeper Optional tier 3
Everything required for today is above. Open these only if you want the explainer, source trail, or download files.
The everyday model and Tier 1 check are the complete required path for this lesson.
Use these checks to keep your place. They are not turned in through the portal.
Check off as you finish
- Worked through the everyday picture and answered its three questions.
- Completed the Tier 1 check in plain words.
Turn in: Disease lesson 9: What Caused Mateo's Cleft?
Go to Schoology to turn this in.
Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Optional legacy technical materials Open only if you want the original notes, vocabulary, artifact, and CER work
Before this page, you should know
- is the number of affected babies per total births; orofacial clefting affects about 1 in 700 live births worldwide, so it is common, not rare.
- By type, lip and together (CLP) is most common at about 45%, with cleft palate only about 40% and cleft lip alone about 15 to 25%.
If not, review
Today's new idea is only
A common like Mateo's is multifactorial: many small genetic influences plus environment crossing a threshold, with usually no single thing to blame.
Goal: Students will explain that nonsyndromic clefts arise from many small genetic influences combined with environmental factors (multifactorial cause), using real twin and risk-factor data, and apply that model to Mateo without blaming a single cause.
Know by the end
- compares how often both twins are affected; identical twins are about 60% concordant for nonsyndromic clefts versus about 5 to 10% for fraternal twins and siblings.
- That identical twins are far more concordant than siblings shows genes clearly matter, but not 100% concordance shows genes are not the whole story.
- The favored model is multifactorial threshold inheritance: many small-effect genes plus environment, with a appearing only when total liability crosses a threshold.
- Among environmental risk factors, maternal smoking is the most robust ( about 1.3, a small nudge); valproic acid raises risk especially for ; 's protective magnitude is debated and presented as an association.
1
What the twin data say
Model start: (about 60% identical versus 5 to 10% siblings) shows genes matter but do not fully decide.
- Because identical twins are far more often concordant than siblings (about 60% versus 5 to 10%), genes clearly matter.
- But because identical twins are not concordant 100% of the time, genes are not the whole story; something else varies too.
2
The multifactorial model
- The favored model is multifactorial: many small-effect genetic variants combine with environmental factors.
- A forms only when total liability crosses a ______ (the ); no single gene and no single exposure decides it.
3
Risk factors, kept honest
- Maternal smoking, the strongest reliable factor, raises risk only modestly ( about ______); valproic acid raises risk especially for ______.
- deficiency is associated with higher risk and supplementation looks protective in some studies, but the magnitude is debated, so it is presented as an association, not a guarantee.
Everything you need for today is on this page. These links are optional.
What to read
Read the short plain-language explanation written for this lesson. Plain-language explainer for this lesson
Why this source matters
This explanation gives you the background for today's idea without making you decode a research paper: A common like Mateo's is multifactorial: many small genetic influences plus environment crossing a threshold, with usually no single thing to blame.
Words to unlock first
Reading moves
- 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.
Stop point
Stop after the final 'Use it now' section. The research citations are available separately for advanced readers.
Your output
Write one claim-evidence sentence: state the main idea, then name the example or evidence that supports it.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Disease domain · Medical Interventions (MI), Unit 2 inheritance and risk
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Write a 3 to 4 sentence counseling response to Mateo's mother asking 'Was it something I did?' that is (1) honest about cause (multifactorial, genes plus environment, threshold), (2) specific (uses one real number), and (3) non-blaming (reflects that she had none of the major risk factors and most clefts happen without one).
Lab / skill
Clinical backbone (cleft team) · Clinical backbone (cleft team)
Everything required for today's decision is already in the case file and plain-language explainer. The links below are original papers and database records for teachers and advanced readers, not assigned student reading.
- American Cleft Palate Craniofacial Association. 2024 Parameters of Care.
- Dixon MJ, et al. 2011. Cleft lip and palate: genetic and environmental influences. Nat Rev Genet. [PMID:21331089]
- Vyas T, et al. 2020. Cleft of lip and palate: A review. J Family Med Prim Care. [PMID:32984097]
- Garland MA, et al. 2020. Environmental mechanisms of orofacial clefts. Birth Defects Res. [PMID:33125192]
- Claim: Mateo's was most likely caused by ________ (one cause / many small causes together).
- Evidence: Identical twins are concordant about ________ percent while siblings are about ________ percent, and the strongest environmental factor (smoking) has an of only about ________.
- Reasoning: Because genes clearly matter but do not fully decide, and environment nudges but rarely decides alone, the cause is best described as ________, which means there is usually no single thing to blame.
How this is graded (rubric)
For: Write a 3 to 4 sentence counseling response to Mateo's mother asking 'Was it something I did?' that is (1) honest about cause (multifactorial, genes plus environment, threshold), (2) specific (uses one real number), and (3) non-blaming (reflects that she had none of the major risk factors and most clefts happen without one).
| Criterion | Proficient | Developing | Beginning |
|---|---|---|---|
| Complete | Every required part of the artifact is present and filled in. | Most parts are present, but one is missing or left blank. | Several parts are missing. |
| Accurate | The science and data are correct and match the evidence. | Mostly correct, with a small factual slip. | Key science or data is wrong. |
| Scientific reasoning (CER) | States a claim, backs it with specific evidence, and explains the reasoning. | Has a claim and evidence, but the reasoning is thin or missing. | Gives an answer with no evidence or reasoning. |
| Professional communication | Clear, organized, and labeled the way a clinician or scientist would write it. | Readable but disorganized or missing labels. | Hard to follow. |
| Submitted | Turned in through the route named under Submit here and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
How the model answer scores against this rubric
- CompleteProficient: Nothing is left blank: the model fills every part of "Write a 3 to 4 sentence counseling response to Mateo's mother asking 'Was it something I did?' that is (1) honest about cause (multifactorial, genes plus environment, threshold), (2) specific (uses one real number), and (3) non-blaming (reflects that she had none of the major risk factors and most clefts happen without one).".
- AccurateProficient: Every number and claim matches the case evidence.
- Scientific reasoning (CER)Proficient: It names a claim, cites the specific evidence, and explains the reasoning, not just the answer.
- Professional communicationProficient: It is organized and labeled like a real chart note.
- SubmittedProficient: It would be attached to your class form or handed in, and confirmed.
What's next: Mateo's came from many small influences working together, not one fixable thing. So if no single cause can be removed, what is the actual plan for the next 18 years of his care?