HBQ1

Chr 16

hemoglobin subunit theta 1

Also known as: HBQ

NCBI Gene: 3049 ENSG00000086506 UniProt: P09105

Theta-globin mRNA is found in human fetal erythroid tissue but not in adult erythroid or other nonerythroid tissue. The theta-1 gene may be expressed very early in embryonic life, perhaps sometime before 5 weeks. Theta-1 is a member of the human alpha-globin gene cluster that involves five functional genes and two pseudogenes. The order of genes is: 5' - zeta - pseudozeta - mu - pseudoalpha-2 -pseudoalpha-1 - alpha-2 - alpha-1 - theta-1 - 3'. Research supports a transcriptionally active role for the gene and a functional role for the peptide in specific cells, possibly those of early erythroid tissue. [provided by RefSeq, Jul 2008]

Active trials

Pathogenic / LP

101

ClinVar variants

Pubs (1 yr)

0.6

Missense Z

1.91

LOEUF

Clinical Summary— HBQ1

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Population Constraint (gnomAD)

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

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ClinVar Variants

61 Pathogenic / Likely Pathogenic· 38 VUS of 101 total submissions

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GeneReview available — HBQ1

Authoritative clinical overview · Recommended first read

Open GeneReview ↗

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

Tolerant — LoF & missense variants common in population

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.

1.91LOEUF

pLI 0.001

Z-score -0.51

OE 1.32 (0.59–1.91)

Tolerant

Highly tolerant — LoF variants common in population

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.

0.59Z-score

OE missense 0.81 (0.66–1.00)

60 obs / 74.3 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.1.32 (0.59–1.91)

0≤0.351.4

Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.81 (0.66–1.00)

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: 4 / 3.0Missense obs/exp: 60 / 74.3Syn Z: 0.03

0.6357th %ile

GOF

0.6735th %ile

LOF

0.2385th %ile

This gene has evidence for multiple mechanisms of pathogenicity (gain-of-function and dominant-negative). Both the Badonyi & Marsh prediction and the broader genomic evidence point to gain-of-function as the predominant mechanism. Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.

GOFprediction above median

DNprediction above median

Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.