Chance or Genetic? Reading Mateo's Family Tree
Is Mateo's a one-time chance event, or is it written into his family?
💡 A pedigree does not by itself prove a gene, but it tells us whether, and how hard, to look for one.
What you will learn
Goal: Students will read and build a three-generation pedigree using standard symbols and use it to tell an from a familial (inherited) one when the family history is sparse and uncertain.
- A pedigree uses standard symbols (squares for males, circles for females, filled for affected, open for unaffected) so any geneticist can read a family at a glance.
- The proband is the person whose case brought the family in, marked with an arrow.
- An appears in one person with no affected relatives; a appears in more than one relative, often across generations.
- About 70% of clefts are and roughly 30% are part of a larger inherited picture.
Model: The intake interview and how geneticists draw a family
You interview Mateo's family and write down what you hear. Mateo (newborn boy) has lip and , and his finds no other birth defects. His mother, father, and older sister have no cleft and no other findings. Both sets of grandparents report no clefts. One distant relative, a great-uncle the family has never met, is remembered in a family story as having had "something done to his lip" as a baby, but nobody is sure it was a cleft and there are no records.
A pedigree is a family tree drawn with agreed-upon symbols: a square is male, a circle is female, an open symbol is unaffected, a filled symbol is affected, a line is a couple, a vertical line down leads to their children, and an arrow marks the proband. Drawn out, Mateo's family shows unaffected grandparents and unaffected parents, an unaffected sister, and only Mateo filled in as the affected proband. Off to the side, the distant great-uncle is drawn dashed and labeled with a question mark because the story is uncertain and unverified. We fill a symbol only when a finding is confirmed.
Explore (work the model before reading on)
- In the pedigree, what symbol is used for an affected male? What symbol marks the proband?
- List every person in Mateo's family whose is CONFIRMED. How many is that, across how many generations?
- If Mateo's were pure chance, you would expect it in only one person with nobody related confirmed to have it. Does the family match that picture, or not?
- There is one distant relative the family thinks may have had a , but no one is sure and there are no records. How much weight should a careful geneticist put on an unverified family story, and what would make it stronger evidence?
- A is sometimes the most obvious feature of a larger inherited syndrome. If a hidden syndrome were present, what kinds of extra clues might a quick miss?
- In one sentence, what pattern (or lack of a clear pattern) did your team find in Mateo's family tree?
Guided notes
Reading the symbols
- A pedigree is a family diagram with squares for males, circles for females, filled for ____ and open for unaffected.
- The person who brings the family to attention is the proband, marked with an ____.
Isolated versus familial
- A is an when it appears in ______ person with no clearly affected relatives.
- It is a when it appears in ______ than one relative, often across generations.
What Mateo's tree shows
- Only Mateo is confirmed, his parents are unaffected, and the one possible relative is an unverified story, so the tree mostly reads as isolated.
- About 70% of clefts are isolated; a sparse pedigree cannot close the case, because a can be the first visible sign of a hidden syndrome.
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.
Track your progress today
Check these off as you work through the lesson, then submit. This tells Mr. Mendoza how you're doing so he can help the class. It does not replace turning in your producible.
Use the code Mr. Mendoza gave you, not your name. Saved on this device.
- Read the Model and answered the Explore questions.
- Filled in the guided notes in my own words.
- Defined the new vocabulary with an example.
- Built the producible: Redraw Mateo's pedigree cleanly with standard symbols, label the proband with an arrow, fill only confirmed findings, mark the uncertain relative with a question mark, and write one chart sentence about whether the case looks isolated, familial, or uncertain.
- Wrote my Claim, Evidence, and Reasoning exit ticket.
Exit ticket (Claim, Evidence, Reasoning)
- Claim: On this sparse history, Mateo's looks most likely (isolated / clearly inherited).
- Evidence: In the pedigree, the only confirmed finding is ____, and the parents are ____.
- Reasoning: A thin family history with one uncertain relative leaves an as the best first read, but it does not rule out a ____, which is why we still owe a screen.
| 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 the right way (Schoology for routine work) and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
- CompleteProficient: Nothing is left blank: the model fills every part of "Redraw Mateo's pedigree cleanly with standard symbols, label the proband with an arrow, fill only confirmed findings, mark the uncertain relative with a question mark, and write one chart sentence about whether the case looks isolated, familial, or uncertain.".
- 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 turned in on Schoology and confirmed.
Where this leads: careers
What's next: Mateo's looks isolated and his parents are unaffected, but a cleft can sometimes be one feature of a hidden syndrome. What would a syndrome look like, and how would we screen for one?