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# Milestones of medical genetics

A short timeline from Mendel's peas to sequencing a newborn's genome in days.

Updated Nov 13, 2026

## Key facts

- 1865: Mendel described the rules of inheritance from pea crosses; they were rediscovered in 1900.
- 1902–1908: Garrod showed that alkaptonuria follows recessive inheritance and called such diseases «inborn errors of metabolism».
- 1910s: Morgan's work on fruit flies placed genes on chromosomes (Nobel Prize 1933).
- 1944: Avery, MacLeod and McCarty showed that DNA carries hereditary information; 1953: the double helix (Nobel Prize 1962).
- 1956: the human chromosome number was set at 46; 1959: trisomy 21 was found in Down syndrome.

## In detail

- 1977: Sanger sequencing; 1980s: DNA markers made linkage mapping possible, leading to the genes for cystic fibrosis (1989) and Huntington disease (1993).
- 1990: the first approved human gene therapy trial, for ADA deficiency.
- 2003: the Human Genome Project completed the reference sequence; 2022: the first truly complete, gap-free human genome.
- 2005 onwards: massively parallel sequencing made exomes and genomes affordable; 2012: CRISPR–Cas9 genome editing; 2023: the first approved CRISPR therapy, for sickle cell disease and β-thalassaemia.

**Also called**
History of genetics

## Clinical notes

- Each step changed practice: karyotyping made chromosome diagnosis possible, linkage brought prenatal diagnosis to families, and sequencing brought diagnosis to most rare-disease clinics.

## Test yourself

Think of the answer, then tap the question to see it.

## Who first described a human disease as an «inborn error of metabolism», and which one?

Archibald Garrod, with alkaptonuria.

## When was trisomy 21 identified as the cause of Down syndrome?

In 1959, three years after the human chromosome number was established.

## What did Avery, MacLeod and McCarty show in 1944?

That DNA is the molecule that carries hereditary information.

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## Connections

## Related conditions 2

- [Down syndrome (trisomy 21)](https://durgical.com/en/conditions/down-syndrome/)
- [Alkaptonuria](https://durgical.com/en/conditions/alkaptonuria/)

## Related 5

- [Milestones of biochemistry](https://durgical.com/en/biochemistry/topics/milestones-of-biochemistry/)
- [DNA structure and chromatin](https://durgical.com/en/biochemistry/topics/dna-structure-and-chromatin/)
- [DNA polymorphisms, linkage and DNA fingerprinting](https://durgical.com/en/biochemistry/topics/dna-polymorphisms-linkage-and-dna-fingerprinting/)
- [Gene therapy](https://durgical.com/en/biochemistry/topics/gene-therapy/)
- [CRISPR-Cas9 and genome editing](https://durgical.com/en/biochemistry/topics/crispr-cas9-and-genome-editing/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [The Nobel Prize in Physiology or Medicine 1933](https://www.nobelprize.org/prizes/medicine/1933/summary/) (NobelPrize.org (Nobel Prize Outreach), 2026); [The Nobel Prize in Physiology or Medicine 1962](https://www.nobelprize.org/prizes/medicine/1962/summary/) (NobelPrize.org (Nobel Prize Outreach), 2026); [The Human Genome Project](https://www.genome.gov/human-genome-project) (National Human Genome Research Institute (NHGRI), 2026).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/topics/milestones-of-medical-genetics/