Revision summary
A pedigree uses standard symbols to show how a trait runs in a family. Dominant, recessive, and X-linked patterns can be read from the chart. Garrod linked such patterns to inborn errors of metabolism. Counselling uses the chart for recurrence risk, especially with consanguinity. Molecular tests refine, they do not replace, the family drawing.
Model answer
Introduction
A pedigree is a family tree drawn with standard symbols so that a Mendelian pattern can be seen. Genetic counselling uses it before any laboratory test.
Body
How the chart works
- Squares are males, circles are females, shading marks the phenotype, and a double bar marks consanguinity.
- Archibald Garrod and later clinical geneticists used such charts for inborn errors. Anthropology still uses them for PTC, albinism, and haemophilia.
- Autosomal dominant traits appear every generation. Recessive traits skip. X-linked traits, as in European royal haemophilia, spare fathers-to-sons.
Counselling use
- The chart estimates recurrence risk for a couple, especially where cousin marriage is common, as in many Indian communities studied by L. D. Sanghvi.
- It cannot replace molecular tests for incomplete penetrance, but it still frames the interview and the ethics of disclosure.
Flow diagram
flowchart TD P[Pedigree] --> M[Mendelian pattern] M --> R[Recurrence risk] R --> C[Counselling]
Conclusion
Pedigree analysis is the first Mendelian instrument of counselling. It turns a family story into a risk figure without pretending that genes are fate.
Quick related
Students also ask
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Is a pedigree enough to name the gene?
No. It names a likely mode of inheritance. Sequencing or biochemistry names the locus.
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Why draw consanguinity?
Cousin marriage raises the chance that two carriers of the same recessive allele meet.
PYQ trend
When UPSC asked this
Related PYQs from other years, newest first. Open a question to read it.
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2025 · Q8(b) · Anthropology GS 1 · 15 marks
'Genome-wide Disease Association Studies (GWAS) advanced our understanding of health and disease.' Discuss -
2024 · Q4(c) · Anthropology GS 1 · 15 marks
What is genetic counseling? Briefly discuss various steps involved in it.
More from this topic
Q8(b) · UPSC Mains 2025 · Anthropology GS 1 · 15 marks
'Genome-wide Disease Association Studies (GWAS) advanced our understanding of health and disease.' Discuss
Genetic imprints in human disease, genetic screening, genetic counseling, human DNA profiling, gene mapping and genome study.
GWAS tests common SNPs across the genome for association with a trait or disease. It showed that many adult diseases are polygenic and pointed to biological pathways. Polygenic scores are research tools, not fate. Limits include European-ancestry bias, missing heritability, and misuse as race biology. Environment, foetal programming and inequality still explain a large share of health. GWAS belongs with genetic markers and with non-Mendelian inheritance.
Q4(c) · UPSC Mains 2024 · Anthropology GS 1 · 15 marks
What is genetic counseling? Briefly discuss various steps involved in it.
Genetic imprints in human disease, genetic screening, genetic counseling, human DNA profiling, gene mapping and genome study.
Genetic counselling helps families understand hereditary and psychosocial implications and choose voluntarily. The sequence is referral, pedigree, diagnosis, risk assessment, consented testing, communication, options and follow-up. Screening estimates risk; a positive screen is not automatically a diagnosis. Risk explanations must include penetrance, variable expression and uncertainty. Thalassaemia and sickle-cell programmes require confirmatory tests and non-stigmatising counselling. Privacy, coercion, sex selection and unequal access are central ethical concerns.
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