TTBK2

Chr 15AD

tau tubulin kinase 2

NCBI Gene: 146057 ENSG00000128881 UniProt: Q6IQ55

Serine/threonine kinase that acts as a key regulator of ciliogenesis: controls the initiation of ciliogenesis by binding to the distal end of the basal body and promoting the removal of CCP110, which caps the mother centriole, leading to the recruitment of IFT proteins, which build the ciliary axoneme. Has some substrate preference for proteins that are already phosphorylated on a Tyr residue at the +2 position relative to the phosphorylation site. Able to phosphorylate tau on serines in vitro (PubMed:23141541). Phosphorylates MPHOSPH9 which promotes its ubiquitination and proteasomal degradation, loss of MPHOSPH9 facilitates the removal of the CP110-CEP97 complex (a negative regulator of ciliogenesis) from the mother centrioles, promoting the initiation of ciliogenesis (PubMed:30375385). Required for recruitment of CPLANE2 and INTU to the mother centriole (By similarity)

Primary Disease Associations & Inheritance

Spinocerebellar ataxia 11MIM #604432

532

ClinVar variants

Pathogenic / LP

1.00

pLI score· haploinsufficient

Active trials

Clinical Summary— TTBK2

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Population Constraint (gnomAD)

Highly constrained gene — heterozygous loss-of-function variants are very rare in the population (pLI 1.00). One damaged copy is likely sufficient to cause disease.

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ClinVar Variants

23 Pathogenic / Likely Pathogenic· 316 VUS of 532 total submissions

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Clinical Trials

1 active or recruiting trial — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

LoF intolerant — likely haploinsufficient

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.

0.26LOEUF

pLI 0.999

Z-score 5.66

OE 0.14 (0.08–0.26)

Highly constrained

Highly LoF-intolerant (top ~10% 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.

1.39Z-score

OE missense 0.85 (0.79–0.91)

558 obs / 658.5 exp

Tolerant

Mild missense constraint

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.0.14 (0.08–0.26)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.85 (0.79–0.91)

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.0.99

0≤1.21.6

LoF obs/exp: 7 / 50.3Missense obs/exp: 558 / 658.5Syn Z: 0.10