# NM_016356.5(DCDC2):c.447C>T (p.Leu149=)

https://sugi.bio/variant/dcdc2-p-leu149

## Summary

**DCDC2 p.Leu149= (c.447C>T)** is classified **Likely benign** in DCDC2 (ClinVar, Single submitter, 1 submitter; last evaluated 2023-11-09). Very rare (popmax 0.00254%, nfe).

**At a glance:** Likely benign · review: Single submitter · 1 submitter · very rare (popmax 0.00254%, nfe)

## For patients & families {#patients}

This is a change in the DCDC2 gene that is classified as likely benign — not considered disease-causing, submitted by 1 submitter.

*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.*

**Support & next steps:** [Find a genetic counselor (NSGC)](https://findageneticcounselor.nsgc.org/).

## Identity {#identity}

| Field | Value |
| --- | --- |
| Gene | [DCDC2](https://sugi.bio/atlas/gene/DCDC2/) |
| Protein change (HGVS p.) | p.Leu149= |
| Coding change (HGVS c.) | c.447C>T |
| MANE Select transcript | [NM_016356](https://www.ncbi.nlm.nih.gov/nuccore/NM_016356) |
| Variant type | single nucleotide variant |
| Location | chr6:24301825-24301825 (GRCh38) |
| ClinVar | [VCV4973897](https://www.ncbi.nlm.nih.gov/clinvar/variation/4973897/) |

**All HGVS expressions:** `NC_000006.11:g.24302053G>A`, `NC_000006.12:g.24301825G>A`, `NG_012829.2:g.86468C>T`, `NM_001195610.2:c.447C>T`, `NM_016356.5:c.447C>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 2.355, GERP 0.964, phastCons 0.998 — highly conserved position (PP3-type support)
- CADD: **PHRED 11.77**. 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: **below the reporting threshold**. This position is scored for a different substitution (G>T, Δ0.26 acceptor gain), so this allele was evaluated and its deltas all fell under Δ0.2 — a prediction of no splicing effect for this allele, not a gap in our data. *No ACMG code assigned.*
- Population frequency (gnomAD v4.1): grpmax **0.00254%** (nfe) · FAF95 0.0018% · FAF99 0.00156% · 30/1,180,032 in the highest group · 37/1,614,176 alleles overall — very rare (popmax 0.00254%, nfe).

| Ancestry group | Allele frequency | 1 in |
| --- | --- | --- |
| Finnish (not grpmax-eligible) | 0.00937% | 10,673 |
| European (non-Finnish) (grpmax) | 0.00254% | 39,334 |
| Remaining individuals (not grpmax-eligible) | 0.0016% | 62,510 |

Finnish shows a higher raw frequency than the grpmax group. gnomAD excludes bottlenecked groups — Finnish, Ashkenazi Jewish, Amish and "Remaining individuals" — from grpmax, because founder effects make their frequencies unrepresentative for filtering. The table is sorted by frequency, so an excluded group can sit above the grpmax row.

*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}

**DCDC2** population constraint: LOEUF 1.062, pLI 1.1753e-09, missense-Z 0.58407. *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):

- **ciliopathy** — Definitive (AR)
- **nonsyndromic genetic hearing loss** — Limited (AR)

## Protein context {#protein}

Residue **149** lies in the doublecortin 2 domain; a β-strand.

AlphaFold model confidence (whole protein): pLDDT 63.93, 17% of residues very-high.

**1 experimental structure(s)** (PDB): [2DNF](https://www.rcsb.org/structure/2DNF).

## Clinical significance {#significance}

**Likely benign** — review status Single submitter *(criteria provided, single submitter)*, last evaluated 2023-11-09.

**Submitter consensus:** unanimous (1/1 Likely benign).

### Submitter classifications {#submitters}

| Submitter | Classification | Review | Method | Date |
| --- | --- | --- | --- | --- |
| Blueprint Genetics | Likely benign | criteria provided, single submitter | clinical testing | 2023-11-09 |

**Reported phenotype names (ClinVar):** not specified, AllHighlyPenetrant.

## Similar variants {#similar}

Related DCDC2 variant pages (same residue, condition, or type): [DCDC2 p.Leu149Phe](/variant/dcdc2-p-leu149phe), [DCDC2 c.294-2A>G](/variant/dcdc2-c-294-minus-2a-g), [DCDC2 c.349-2A>G](/variant/dcdc2-c-349-minus-2a-g), [DCDC2 c.705-2A>G](/variant/dcdc2-c-705-minus-2a-g), [DCDC2 p.Leu297Ter](/variant/dcdc2-p-leu297ter), [DCDC2 p.Met1Arg](/variant/dcdc2-p-met1arg), [DCDC2 p.Ser128Ter](/variant/dcdc2-p-ser128ter), [DCDC2 p.Ala153Gly](/variant/dcdc2-p-ala153gly).

### Data sources & attribution {#sources}

ClinVar (NCBI — public domain, built 2026-10-14); gnomAD v4.1 (Broad Institute, built 2026-10-14); 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 2026-10-14); 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 4973897). 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.*