Trait

Absent knee jerk reflex

Clinical name: Absent patellar reflexes

Absence of the knee jerk reflex, which can normally be elicited by tapping the patellar tendon with a reflex hammer just below the patella.

HPO HP:0006844

Body system: Abnormality of limbs Abnormality of the nervous system

This page as data

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page <- fromJSON(url)
page$trait$name

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16 genes linked to Absent knee jerk reflex

Changes in these genes cause rare conditions in which Absent knee jerk reflex is seen. Most people with this trait have none of those conditions, and a gene on this list says nothing about anyone's own genome.

Gene	How often it is seen	Conditions
ARHGAP19Rho GTPase activating protein 19	Always	In 1 condition
BORCS8BLOC-1 related complex subunit 8	Always	In 1 condition
PSMC1proteasome 26S subunit, ATPase 1	Always	In 1 condition
SMN1survival of motor neuron 1, telomeric	Always	In 1 condition
SMN2survival of motor neuron 2, centromeric	Always	In 1 condition
GNB4G protein subunit beta 4	Very often (80–99%)	In 1 condition
FBLN5fibulin 5	Often (30–79%)	In 1 condition
HSPB3heat shock protein family B (small) member 3	Often (30–79%)	In 1 condition
KLHL9kelch like family member 9	Often (30–79%)	In 1 condition
LIFRLIF receptor subunit alpha	Often (30–79%)	In 2 conditions
MYH14myosin heavy chain 14	Often (30–79%)	In 1 condition
PMP2peripheral myelin protein 2	Often (30–79%)	In 1 condition
WARS1tryptophanyl-tRNA synthetase 1	Often (30–79%)	In 1 condition
BAG3BAG cochaperone 3	Sometimes (5–29%)	In 1 condition
ERLIN1ER lipid raft associated 1	Sometimes (5–29%)	In 1 condition
MFN2mitofusin 2	Sometimes (5–29%)	In 1 condition

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Broader traits

Areflexia of lower limbs

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the trait, its names, its definition and the genes linked to it. Find out more at hpo.jax.org.
Data release 2026.10.17-8666dff2.

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