FAM20B

Chr 1

FAM20B glycosaminoglycan xylosylkinase

Also known as: gxk1

Enables phosphotransferase activity, alcohol group as acceptor. Predicted to be involved in proteoglycan biosynthetic process. Located in Golgi apparatus and nucleoplasm. [provided by Alliance of Genome Resources, Jul 2025]

ResearchGenerating clinical summary…
LOEUF 0.91
Clinical SummaryFAM20B
🧬
Gene-Disease Validity (ClinGen)
congenital disorder of glycosylation · ARLimited

Limited evidence — not for standalone diagnostic reporting

Population Constraint (gnomAD)
Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.
📋
ClinVar Variants
53 VUS of 66 total submissions
Some data sources returned errors (1)

omim: Error: OMIM fetch failed: 429

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Tolerant — LoF & missense variants common in population
LoF Constraint?
0.91LOEUF
pLI 0.000
Z-score 1.86
OE 0.56 (0.360.91)
Tolerant

Typical tolerance to LoF variation

Missense Constraint?
0.98Z-score
OE missense 0.82 (0.730.93)
196 obs / 238.6 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?
LoF OE?0.56 (0.360.91)
00.351.4
Missense OE?0.82 (0.730.93)
00.61.4
Synonymous OE?0.98
01.21.6
LoF obs/exp: 12 / 21.3Missense obs/exp: 196 / 238.6Syn Z: 0.16

ClinVar Variant Classifications

66 submitted variants in ClinVar

Classification Summary

VUS53
Likely Benign1
53
VUS
1
Likely Benign

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
0
0
0
0
0
Likely Pathogenic
0
0
0
0
0
VUS
1
52
0
0
53
Likely Benign
0
0
0
1
1
Benign
0
0
0
0
0
Total1520154

LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly

View in ClinVar →

25 pathogenic / likely-pathogenic (of 28) ClinVar copy-number / structural variants overlap FAM20B — these span large chromosomal regions, not the gene specifically, and are excluded from the counts above. Explore in CNV tools →

Protein Context — Lollipop Plot

FAM20B · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

No active trials found for this gene.

Search ClinicalTrials.gov →