DDHD1

Chr 14AR

DDHD domain containing 1

NCBI Gene: 80821 ENSG00000100523 UniProt: Q8NEL9

Phospholipase A1 (PLA1) that hydrolyzes ester bonds at the sn-1 position of glycerophospholipids producing a free fatty acid and a lysophospholipid (Probable) (PubMed:20359546, PubMed:22922100). Prefers phosphatidate (1,2-diacyl-sn-glycero-3-phosphate, PA) as substrate in vitro, but can efficiently hydrolyze phosphatidylinositol (1,2-diacyl-sn-glycero-3-phospho-(1D-myo-inositol), PI), as well as a range of other glycerophospholipid substrates such as phosphatidylcholine (1,2-diacyl-sn-glycero-3-phosphocholine, PC), phosphatidylethanolamine (1,2-diacyl-sn-glycero-3-phosphoethanolamine, PE), phosphatidylserine (1,2-diacyl-sn-glycero-3-phospho-L-serine, PS) and phosphatidylglycerol (1,2-diacyl-sn-glycero-3-phospho-(1'-sn-glycerol), PG) (Probable) (PubMed:20359546). Involved in the regulation of the endogenous content of polyunsaturated PI and PS lipids in the nervous system. Changes in these lipids extend to downstream metabolic products like PI phosphates PIP and PIP2, which play fundamental roles in cell biology (By similarity). Regulates mitochondrial morphology (PubMed:24599962). These dynamic changes may be due to PA hydrolysis at the mitochondrial surface (PubMed:24599962). May play a regulatory role in spermatogenesis or sperm function (PubMed:24599962)

Primary Disease Associations & Inheritance

Spastic paraplegia 28, autosomal recessiveMIM #609340

603

ClinVar variants

Pathogenic / LP

0.90

pLI score· haploinsufficient

Active trials

Clinical Summary— DDHD1

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Population Constraint (gnomAD)

Highly constrained gene — heterozygous loss-of-function variants are very rare in the population (pLI 0.90). One damaged copy is likely sufficient to cause disease.

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ClinVar Variants

27 Pathogenic / Likely Pathogenic· 259 VUS of 603 total submissions

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.

0.34LOEUF

pLI 0.902

Z-score 4.93

OE 0.19 (0.11–0.34)

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.

1.18Z-score

OE missense 0.85 (0.79–0.92)

427 obs / 501.4 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.0.19 (0.11–0.34)

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 (0.79–0.92)

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.1.02

0≤1.21.6

LoF obs/exp: 8 / 42.8Missense obs/exp: 427 / 501.4Syn Z: -0.25