Is ALPL p.Tyr421= (c.1263C>T) pathogenic?

ALPL p.Tyr421= (c.1263C>T) is classified Conflicting classifications of pathogenicity in ALPL (ClinVar, Conflicting submitters, 3 submitters; last evaluated 2024-02-19). Very rare (popmax 0.000678%, nfe); Associated with hypophosphatasia.

What condition is associated with ALPL p.Tyr421= (c.1263C>T)?

ALPL p.Tyr421= (c.1263C>T) is associated with hypophosphatasia (ClinVar).

How common is ALPL p.Tyr421= (c.1263C>T) in the general population?

ALPL p.Tyr421= (c.1263C>T) is very rare (popmax 0.000678%, nfe) (gnomAD).

How is Hypophosphatasia inherited?

Typically Autosomal dominant, Autosomal recessive (Orphanet). A genetic counselor can assess individual risk for a family.

ALPL p.Tyr421=

c.1263C>T · rs780762265 · VCV876710

Conflicting classifications of pathogenicity Conflicting submitters

Classification

Conflicting classifications of pathogenicity

ClinVar

Review

Conflicting submitters ★☆☆☆

ClinVar · 3 submitters

gnomAD v4.1

Rare

very rare (popmax 0.000678%, nfe)

Conditions

hypophosphatasia

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 4	GERP 1.8, phastCons 1
Overall
CADD	11.5	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000678% European (non-Finnish) · 8/1,179,952 alleles

Filtering AF 0.000292% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000211%

Overall 0.000547% 8/1,461,796 alleles · very rare

Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.

Variant & gene context

Gene: ALPL
Protein: p.Tyr421=
Coding: c.1263C>T
MANE Select: NM_000478
dbSNP: rs780762265
Type: single nucleotide variant
Location: chr1:21576595 (GRCh38)
Gene constraint: LOEUF 0.987 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 93.74 · 5 PDB

Full ALPL gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

hypophosphatasia — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Hypophosphatasia (Orphanet):

Inheritance: Autosomal dominant, Autosomal recessive
Onset: All ages

Similar variants

ALPL p.Tyr421Cys Uncertain significance ★ ⚠ same residue
ALPL c.1190-2A>T Pathogenic ★★ same condition
ALPL c.182-1G>A Pathogenic/Likely pathogenic ★★ same condition
ALPL c.182-2A>G Pathogenic/Likely pathogenic ★★ same condition
ALPL c.297+1G>A Pathogenic/Likely pathogenic ★★ same condition
ALPL c.298-1G>A Pathogenic ★★ same condition
ALPL c.472+1G>A Pathogenic ★★ same condition
ALPL c.62-1G>C Pathogenic/Likely pathogenic ★★ same condition

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/alpl-p-tyr421 (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown