MYL1

Chr 2AR

myosin light chain 1

Also known as: CMYO14, CMYP14, MLC-1, MLC1, MLC1/3, MLC1F, MLC3F, MYOFTA

NCBI Gene: 4632 ENSG00000168530 UniProt: P05976 OMIM: 160780

The protein is a non-regulatory myosin light chain required for proper formation and maintenance of myofibers in fast skeletal muscle. Mutations cause autosomal recessive congenital myopathy with skeletal muscle involvement. The gene is not highly constrained against loss-of-function variants.

OMIM ResearchSummary from RefSeq, UniProt

Myosin is a hexameric ATPase cellular motor protein. It is composed of two heavy chains, two nonphosphorylatable alkali light chains, and two phosphorylatable regulatory light chains. This gene encodes a myosin alkali light chain expressed in fast skeletal muscle. Two transcript variants have been identified for this gene. [provided by RefSeq, Jul 2008]

OMIM ResearchGenerating clinical summary…

LOFmechanismARLOEUF 1.361 OMIM phenotype

Clinical Summary— MYL1

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Gene-Disease Validity (ClinGen)

congenital myopathy · ARLimited

Limited evidence — not for standalone diagnostic reporting

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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

2 unique Pathogenic / Likely Pathogenic· 23 VUS of 54 total submissions

Explore recent and relevant literature in Research Assistant →

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD

Tolerant — LoF & missense variants common in population

LoF Constraint?

1.36LOEUF

pLI 0.000

Z-score 0.79

OE 0.73 (0.41–1.36)

Tolerant

Highly tolerant — LoF variants common in population

Missense Constraint?

0.52Z-score

OE missense 0.86 (0.73–1.02)

95 obs / 110.5 exp

Tolerant

Mild missense constraint

Observed / Expected Ratios?

LoF OE?0.73 (0.41–1.36)

0≤0.351.4

Missense OE?0.86 (0.73–1.02)

0≤0.61.4

Synonymous OE?1.10

0≤1.21.6

LoF obs/exp: 7 / 9.7Missense obs/exp: 95 / 110.5Syn Z: -0.50

Curated Mechanism (G2P)Gene2Phenotype (DDG2P) ↗

moderateMYL1-related myopathy, congenital, with fast-twitch (type II) fiber atrophyLOFAR

This gene — mechanism propensity

Predictions shown for reference only — model trained on dominant genes, not applicable to AR conditions.

0.74top 25%

GOF

0.74top 25%

LOF

0.2775th %ile

The Badonyi & Marsh prediction model was trained exclusively on dominant disease genes. Predictions are not reliable for genes with autosomal recessive inheritance and are shown at reduced opacity for reference only.

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

ClinVar Variant Classifications

54 submitted variants in ClinVar

ClinVar

Classification Summary

Likely Pathogenic2

VUS23

Likely Benign9

Benign18

Likely Pathogenic

VUS

Likely Benign

Benign

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

Classification	LoF	Missense + Inframe	Non-coding	Synonymous	Total
Pathogenic	0	0	0	0	0
Likely Pathogenic	1	0	1	0	2
VUS	0	23	0	0	23
Likely Benign	1	3	1	4	9
Benign	2	1	15	0	18
Total	4	27	17	4	52

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

View in ClinVar →

23 pathogenic / likely-pathogenic (of 28) ClinVar copy-number / structural variants overlap MYL1 — these span large chromosomal regions, not the gene specifically, and are excluded from the counts above. Explore in CNV tools →