ITPR3

Chr 6AD

inositol 1,4,5-trisphosphate receptor type 3

NCBI Gene: 3710 ENSG00000096433 UniProt: Q14573

Inositol 1,4,5-trisphosphate-gated calcium channel that, upon 1D-myo-inositol 1,4,5-trisphosphate binding, transports calcium from the endoplasmic reticulum lumen to cytoplasm, thus releasing the intracellular calcium and therefore participates in cellular calcium ion homeostasis (PubMed:32949214, PubMed:37898605, PubMed:8081734, PubMed:8288584, PubMed:39560673). 1D-myo-inositol 1,4,5-trisphosphate binds to the ligand-free channel without altering its global conformation, yielding the low-energy resting state, then progresses through resting-to preactivated transitions to the higher energy preactivated state, which increases affinity for calcium, promoting binding of the low basal cytosolic calcium at the juxtamembrane domain (JD) site, favoring the transition through the ensemble of high-energy intermediate states along the trajectory to the fully-open activated state (PubMed:30013099, PubMed:35301323, PubMed:37898605). Upon opening, releases calcium in the cytosol where it can bind to the low-affinity cytoplasmic domain (CD) site and stabilizes the inhibited state to terminate calcium release (PubMed:30013099, PubMed:35301323, PubMed:37898605)

Primary Disease Associations & Inheritance

Charcot-Marie-Tooth disease, demyelinating, type 1JMIM #620111

Immunodeficiency 133 with ectodermal dysplasia with or without peripheral neuropathyMIM #621254

539

ClinVar variants

Pathogenic / LP

0.00

pLI score

Active trials

Clinical Summary— ITPR3

⚡

Population Constraint (gnomAD)

Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.

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ClinVar Variants

10 Pathogenic / Likely Pathogenic· 297 VUS of 539 total submissions

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

Missense constrained — critical functional residues

LoF Constraint?LOEUF (Loss-of-function Observed/Expected Upper bound Fraction) is the upper bound of the 90% CI for LoF OE — the preferred gnomAD v4 metric. Lower = more intolerant to LoF. LOEUF < 0.35 = highly constrained.

0.57LOEUF

pLI 0.000

Z-score 5.70

OE 0.46 (0.37–0.57)

Moderately constrained

More LoF-intolerant than ~75% of genes

Missense Constraint?Missense Z-score: standard deviations fewer missense variants observed vs. expected. Z > 3.09 (p < 0.001) = gene does not tolerate missense variation. OE missense < 0.6 is also considered constrained.

4.55Z-score

OE missense 0.69 (0.65–0.72)

1144 obs / 1667.0 exp

Constrained

Highly missense-constrained (top ~0.1%)

Observed / Expected Ratios?Shaded band = 90% confidence interval. Vertical tick = point estimate. Grey threshold line = gnomAD constraint cutoff for that variant class.

LoF OE?Ratio of observed to expected LoF variants. Upper CI bound (LOEUF) ≤ 0.35 = strong LoF constraint signal.0.46 (0.37–0.57)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.69 (0.65–0.72)

0≤0.61.4

Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.0.92

0≤1.21.6

LoF obs/exp: 59 / 128.8Missense obs/exp: 1144 / 1667.0Syn Z: 1.69