# NM_000263.4(NAGLU):c.1662C>T (p.Pro554=)

https://sugi.bio/variant/naglu-p-pro554

## Summary

**NAGLU p.Pro554= (c.1662C>T)** is classified **Conflicting classifications of pathogenicity** in NAGLU (ClinVar, Conflicting submitters, 6 submitters; last evaluated 2026-01-14). Ultra-rare (popmax 0.0337%, nfe); Associated with mucopolysaccharidosis type 3B.

**At a glance:** Conflicting classifications of pathogenicity · review: Conflicting submitters · rsID rs368521316 · 6 submitters · 2 linked conditions · ultra-rare (popmax 0.0337%, nfe)

## For patients & families {#patients}

This is a change in the NAGLU gene that is of uncertain or conflicting significance (submitters disagree on it), submitted by 6 submitters, and is linked to mucopolysaccharidosis type 3B.

*Reference information, not medical advice, and not a prediction for any individual. A genetic counselor or clinician can interpret what it means for you and your family.*

|  |  |
| --- | --- |
| Typical inheritance (of this condition) | Autosomal recessive |
| Age of onset (of this condition) | Childhood |
| Prevalence | 1-9 / 1 000 000 (Brazil) |
| Clinical trials | 15 registered for this condition — see ClinicalTrials.gov |
| Diagnostic panels | NAGLU is a diagnostic-grade gene on 11 Genomics England panels |

**Commonly reported features of Mucopolysaccharidosis type 3** (across patients with this condition; presentation varies — frequencies from Orphanet):

- Chronic otitis media — Very frequent (99-80%)
- Delayed speech and language development — Very frequent (99-80%)
- Malabsorption — Very frequent (99-80%)
- Coarse hair — Very frequent (99-80%)
- Generalized hirsutism — Very frequent (99-80%)
- Progressive neurologic deterioration — Very frequent (99-80%)
- Sleep abnormality — Very frequent (99-80%)
- Urinary glycosaminoglycan excretion — Very frequent (99-80%)

**Support & next steps:** [Condition overview & support (NIH GARD)](https://rarediseases.info.nih.gov/diseases/0007072/index) · [Find a genetic counselor (NSGC)](https://findageneticcounselor.nsgc.org/).

## Identity {#identity}

| Field | Value |
| --- | --- |
| Gene | [NAGLU](https://sugi.bio/atlas/gene/NAGLU/) |
| Protein change (HGVS p.) | p.Pro554= |
| Coding change (HGVS c.) | c.1662C>T |
| MANE Select transcript | [NM_000263](https://www.ncbi.nlm.nih.gov/nuccore/NM_000263) |
| dbSNP | [rs368521316](https://www.ncbi.nlm.nih.gov/snp/rs368521316/) |
| Variant type | single nucleotide variant |
| Location | chr17:42543668-42543668 (GRCh38) |
| ClinVar | [VCV323302](https://www.ncbi.nlm.nih.gov/clinvar/variation/323302/) |

**All HGVS expressions:** `NC_000017.10:g.40695686C>T`, `NC_000017.11:g.42543668C>T`, `NG_011552.1:g.12736C>T`, `NM_000263.4:c.1662C>T`

## Computational & population evidence {#evidence}

**Concordance:** Mixed / partial computational evidence (see below).

- **Missense predictors (AlphaMissense/REVEL/SaProt) do not apply** to this variant type — they score amino-acid substitutions only. For non-missense variants the computational signal comes from conservation (below), not from a missing predictor score.
- Conservation: phyloP -9.784, GERP -4.76 — fast-evolving / accelerated position
- CADD: **PHRED 0.043**. No single ClinGen-calibrated threshold exists and the expert panels that use CADD disagree — GUCY2D/AIPL1 require ≥ 20.0 for an untranslated-region variant, ABCA4 ≥ 28.1 for a synonymous or indel variant, the Pulmonary Hypertension panel imports Pejaver 2022's missense-calibrated numbers, and the Antibody Deficiencies panel declines CADD entirely for PIK3CD. CADD v1.7 also incorporates Zoonomia phyloP, so it partly re-expresses the conservation above. *Descriptive; no threshold applied.*
- SpliceAI: **not assessed** — no allele at this position is in our SpliceAI release, either because it lies outside the scored MANE transcript scope or because every allele is below Δ0.2. We cannot tell which, so this claims neither; absence is not evidence against a splicing effect.
- Population frequency (gnomAD v4.1): grpmax **0.0337%** (nfe) · FAF95 0.0309% · FAF99 0.0299% · 398/1,180,022 in the highest group · 426/1,613,062 alleles overall — ultra-rare (popmax 0.0337%, nfe).

| Ancestry group | Allele frequency | 1 in |
| --- | --- | --- |
| European (non-Finnish) (grpmax) | 0.0337% | 2,965 |
| Remaining individuals (not grpmax-eligible) | 0.024% | 4,165 |
| Middle Eastern | 0.0164% | 6,084 |
| South Asian | 0.011% | 9,109 |
| African / African-American | 0.00267% | 37,475 |

*Computational predictors are not independent (ClinGen Variant Classification guidance): AlphaMissense (Cheng et al. 2023) carries the ACMG weight for missense and conservation (phyloP/GERP/phastCons) for non-missense; REVEL (Pejaver-2022 calibrated strength bands) and SaProt (Su et al. 2023, structure-aware, ClinVar-independent protein language model, raw LLR) are shown as orthogonal agreement signals, not additive. For frequency, the gnomAD v4.1 grpmax filtering allele frequency (FAF95) is ClinGen's designated BA1/BS1 input (gnomAD v4 guidance v3.0, June 2025); BA1/BS1 thresholds are disease-specific, not a blanket 5%. Predictions, not a clinical determination.*

## Gene constraint & dosage {#gene-context}

**NAGLU** population constraint: LOEUF 1.029, pLI 2.3821e-09, missense-Z 0.096459. *Lower LOEUF and higher pLI indicate a gene that tolerates loss-of-function poorly; ClinGen dosage is the curated haploinsufficiency call.*

Curated gene–disease validity (ClinGen):

- **mucopolysaccharidosis type 3B** — Definitive (AR)

## Protein context {#protein}

Residue **554** lies in an α-helix; a UniProt-annotated variant site (in mps3b).

AlphaFold model confidence (whole protein): pLDDT 97.19, 97% of residues very-high.

**1 experimental structure(s)** (PDB): [4XWH](https://www.rcsb.org/structure/4XWH).

## What this gene does {#gene-function}

*Describes the biological roles of NAGLU (the gene this variant disrupts) — not effects measured for this specific variant. A damaging variant is expected to affect these functions and pathways; the degree depends on the variant.*

**How this variant is thought to act:** NAGLU participates in disease-associated pathways. In Reactome, NAGLU is annotated in disease pathway(s) including **MPS IIIB - Sanfilippo syndrome B**.

**Disease mechanism (Reactome):** NAGLU loss or alteration is curated in [MPS IIIB - Sanfilippo syndrome B](https://reactome.org/content/detail/R-HSA-2206282).

### Pathways affected {#pathways}

NAGLU participates in **2 Reactome pathways** (⚕ = disease pathway):

| Pathway (Reactome) | Evidence |
| --- | --- |
| ⚕ [MPS IIIB - Sanfilippo syndrome B](https://reactome.org/content/detail/R-HSA-2206282) | curated |
| [HS-GAG degradation](https://reactome.org/content/detail/R-HSA-2024096) | curated |

## Clinical significance {#significance}

**Conflicting classifications of pathogenicity** — review status Conflicting submitters *(criteria provided, conflicting classifications)*, last evaluated 2026-01-14.

**Submitter consensus:** conflicting (5 Likely benign, 1 Uncertain significance).

**Submission history:** 6 submissions (2018–2026); classifications have differed over time.

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Labcorp Genetics (formerly Invitae), Labcorp | Likely benign | criteria provided, single submitter | clinical testing | 2026-01-14 |
| Blueprint Genetics | Likely benign | criteria provided, single submitter | clinical testing | 2024-11-15 |
| Illumina Laboratory Services, Illumina | Uncertain significance | criteria provided, single submitter | clinical testing | 2018-01-13 |
| Natera, Inc. | Likely benign | no assertion criteria provided | clinical testing | 2020-12-29 |
| PreventionGenetics, part of Exact Sciences | Likely benign | no assertion criteria provided | clinical testing | 2019-10-28 |
| Women's Health and Genetics/Laboratory Corporation of America, LabCorp | Likely benign | criteria provided, single submitter | clinical testing | 2025-10-13 |

## Associated conditions {#conditions}

[mucopolysaccharidosis type 3B](https://sugi.bio/atlas/disease/mucopolysaccharidosis-type-3b/), [Charcot-Marie-Tooth disease axonal type 2V](https://sugi.bio/atlas/disease/charcot-marie-tooth-disease-axonal-type-2v/).

**Reported phenotype names (ClinVar):** Mucopolysaccharidosis, MPS-III-B, Charcot-Marie-Tooth disease axonal type 2V, NAGLU-related disorder, not specified, NAGLU-related condition, MUCOPOLYSACCHARIDOSIS, TYPE IIIB, N-ACETYL-ALPHA-D-GLUCOSAMINIDASE DEFICIENCY, NAGLU DEFICIENCY, SANFILIPPO SYNDROME B, Mucopolysaccharidosis type IIIB (Sanfilippo B).

## Similar variants {#similar}

Related NAGLU variant pages (same residue, condition, or type): [NAGLU p.Pro554Leu](/variant/naglu-p-pro554leu), [NAGLU p.Pro554Ser](/variant/naglu-p-pro554ser), [NAGLU c.1021+1G>A](/variant/naglu-c-1021-plus-1g-a), [NAGLU c.1022-2A>G](/variant/naglu-c-1022-minus-2a-g), [NAGLU c.383+1G>T](/variant/naglu-c-383-plus-1g-t), [NAGLU c.384-1G>A](/variant/naglu-c-384-minus-1g-a), [NAGLU c.531+1G>A](/variant/naglu-c-531-plus-1g-a), [NAGLU c.531+1G>C](/variant/naglu-c-531-plus-1g-c).

### Data sources & attribution {#sources}

ClinVar (NCBI — public domain, built 2026-10-14); gnomAD v4.1 (Broad Institute, built 2026-10-06); AlphaMissense (Cheng et al. 2023, © Google DeepMind — CC BY 4.0, built 2026-01-27); REVEL (Ioannidis et al. 2016 — ODbL, built 2026-07-13); SaProt (Su et al. 2023 — MIT, built 2026-07-14); SpliceAI (Illumina — free for non-commercial use, built 2026-10-13); CADD (Rentzsch et al. 2019, University of Washington — free for non-commercial use, built 2026-10-10); Conservation (phyloP/phastCons/GERP) (UCSC hg38 470-way mammal (Hiller Lab) + Ensembl Compara, built 2026-07-12); gnomAD Non-coding Constraint (Gnocchi) (Chen et al. 2024, Broad Institute — CC0, built 2026-10-11); gnomAD Regional Missense Constraint (Broad Institute — CC0, built 2026-10-13); Pangolin (Zeng & Li 2022 — CC BY 4.0, built 2026-10-11); Repeat regions (UCSC — RepeatMasker, TRF, segmental duplications, built 2026-10-11); ClinGen (ClinGen, built 2026-09-22); UniProt (CC BY 4.0); Reactome / GO (CC BY 4.0, built 2026-09-23); MaveDB (per-record license, built 2026-10-11); CIViC (CC0, built 2026-09-22); Orphanet (Orphanet, built 2026-06-12)

*Primary record: NCBI ClinVar (variation 323302). Classifications reflect these databases as of the page's build date and may change. Free reference use — not medical advice; consult the primary submitters and a clinician.*