Leukoencephalopathy, porphyria-related

Summary

Leukoencephalopathy, porphyria-related (MONDO:0958226) is a disease with 1 cohort gene.

At a glance

• Cohort genes: 1
• ClinVar variants: 7

Clinical features

No curated clinical features (Orphanet) for this disease.

Identifiers

Disease identifiers

Field	Value
Canonical name	leukoencephalopathy, porphyria-related
Mondo ID	MONDO:0958226
OMIM	620711
UMLS	C5935575
MedGen	1862491
GARD	0026976
Is cancer (heuristic)	no

Data availability: 7 ClinVar variants.

Disease family

Classification path: disease › human disease › disease by body system or component › nervous system disorder › central nervous system disorder › neurodegenerative disease › inherited neurodegenerative disorder › leukodystrophy › leukoencephalopathy, porphyria-related

Related subtypes (64): Alexander disease, cerebrotendinous xanthomatosis, polycystic lipomembranous osteodysplasia with sclerosing leukoencephaly, dermatoleukodystrophy, Krabbe disease, Sjogren-Larsson syndrome, Canavan disease, Pelizaeus-Merzbacher spectrum disorder, hereditary spastic paraplegia 2, megalencephalic leukoencephalopathy with subcortical cysts, ribose-5-P isomerase deficiency, hypomyelinating leukodystrophy 5, leukoencephalopathy with brain stem and spinal cord involvement-high lactate syndrome, hypomyelinating leukodystrophy 6, cystic leukoencephalopathy without megalencephaly, sterol carrier protein 2 deficiency, leukoencephalopathy-thalamus and brainstem anomalies-high lactate syndrome, hypomyelination with brain stem and spinal cord involvement and leg spasticity, leukoencephalopathy with mild cerebellar ataxia and white matter edema, progressive encephalopathy with leukodystrophy due to DECR deficiency, hypomyelinating leukodystrophy 9, multiple mitochondrial dysfunctions syndrome 4, hypomyelinating leukodystrophy 10, hypomyelinating leukodystrophy 12, hypomyelinating leukodystrophy 13, leukoencephalopathy with bilateral anterior temporal lobe cysts, progressive cavitating leukoencephalopathy, Pelizaeus-Merzbacher-like disease, CADDS, adrenoleukodystrophy, non-progressive predominantly posterior cavitating leukoencephalopathy with peripheral neuropathy, Aicardi-Goutieres syndrome, metachromatic leukodystrophy, peroxisome biogenesis disorder, unknown leukodystrophy, ravine syndrome, leukodystrophy, hypomyelinating, 22, leukodystrophy, hypomyelinating, 23, with ataxia, deafness, liver dysfunction, and dilated cardiomyopathy, neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination, leukodystrophy, hypomyelinating, 18, leukodystrophy, hypomyelinating, 19, transient infantile, spastic ataxia 8, autosomal recessive, with hypomyelinating leukodystrophy, leukodystrophy, hypomyelinating, 14, leukodystrophy, hypomyelinating, 20, early-onset calcifying leukoencephalopathy-skeletal dysplasia, c11orf73-related autosomal recessive hypomyelinating leukodystrophy, alkaline ceramidase 3 deficiency, leukodystrophy, hypomyelinating, 15, leukodystrophy, hypomyelinating, 16, leukodystrophy, hypomyelinating, 17, POLR-related leukodystrophy, leukoencephalopathy, diffuse hereditary, with spheroids 1, leukoencephalopathy with vanishing white matter, leukodystrophy, hypomyelinating, 24, leukodystrophy, childhood-onset, remitting, leukodystrophy, hypomyelinating, 25, leukodystrophy, hypomyelinating, 26, with chondrodysplasia, adult-onset progressive leukoencephalopathy-early-onset deafness, episodic memory defect leukoencephalopathy, leukodystrophy, hypomyelinating, 28, leukodystrophy, demyelinating, adult-onset, leukodystrophy, adult-onset, autosomal dominant, without amyloid angiopathy, leukoencephalopathy without lacunae, adult-onset, AARS1-related leukoencephalopathy

Genetics & variants

GWAS landscape

No GWAS associations recorded — common-variant (GWAS) studies don’t cover this disease (typical for Mendelian / rare diseases). See the curated gene cohort and Mendelian overlap below.

Variant details and genetic-evidence tiers

ClinVar germline variants

7 retrieved; paginated sample, class counts are floors:

3 uncertain significance, 2 pathogenic/likely pathogenic, 1 conflicting classifications of pathogenicity, 1 pathogenic

ClinVar	Variant (HGVS)	Gene	Classification	Review
1446	NM_000190.4(HMBS):c.500G>A (p.Arg167Gln)	HMBS	Pathogenic/Likely pathogenic	criteria provided, multiple submitters, no conflicts
1509204	NM_000190.4(HMBS):c.500G>C (p.Arg167Pro)	HMBS	Pathogenic/Likely pathogenic	criteria provided, multiple submitters, no conflicts
3024100	NM_000190.4(HMBS):c.251C>A (p.Ala84Asp)	HMBS	Pathogenic	no assertion criteria provided
161252	NM_000190.4(HMBS):c.257A>T (p.Glu86Val)	HMBS	Conflicting classifications of pathogenicity	criteria provided, conflicting classifications
1382821	NM_000190.4(HMBS):c.661G>A (p.Gly221Ser)	HMBS	Uncertain significance	criteria provided, multiple submitters, no conflicts
161253	NM_000190.4(HMBS):c.674G>A (p.Arg225Gln)	HMBS	Uncertain significance	criteria provided, multiple submitters, no conflicts
2735769	NM_000190.4(HMBS):c.604G>T (p.Val202Leu)	HMBS	Uncertain significance	criteria provided, multiple submitters, no conflicts

Genes & proteins

Mendelian disease overlap and somatic drivers

GenCC: 0 · Orphanet: 1 · OMIM-shared: 0 · Dual-evidence (GWAS+Mendelian): 0

Orphanet rare-disease linkage (cohort genes)

Gene	Orphanet ID	Rare disease
HMBS	Orphanet:79276	Acute intermittent porphyria

Cohort genes → proteins

1 cohort genes, 1 distinct canonical proteins.

Evidence partition

Subset	Genes
multi_evidence	1

Cohort genes (full)

Symbol	HGNC	Ensembl	UniProt	Name	Evidence
HMBS	HGNC:4982	ENSG00000256269	P08397	Porphobilinogen deaminase	clinvar

Cohort function summary

Lead sentence per gene, UniProt-curated.

Symbol	Protein name	Function (lead sentence)
HMBS	Porphobilinogen deaminase	As part of the heme biosynthetic pathway, catalyzes the sequential polymerization of four molecules of porphobilinogen to form hydroxymethylbilane, also known as preuroporphyrinogen.

Protein-family classification

Druggable: 1 · Difficult: 0 · Unknown: 0 · Druggable fraction: 1.0

Family distribution

Cohort families vs a genome-wide background (hypergeometric, BH-FDR; fold = observed/expected). Counts kept; sorted by enrichment, so the catch-all Other/Unknown bucket no longer leads.

Family	Genes	Fold	FDR
Enzyme (other)	1	12.0×	0.083

Per-gene assignment

Symbol	Family	Druggable?	EC	InterPro (top 3)
HMBS	Enzyme (other)	yes	2.5.1.61	HemC, Porphobilin_deaminase_N, Porphobilinogen_deaminase_C

Expression context

Cohort genes with no expression data: 0.

1 cohort gene are a single-cell marker in ≥1 SCXA experiment.

Breadth distribution (Bgee present_calls)

Bucket	Genes
narrow (1-5 tissues)	0
moderate (6-20)	0
broad (>20)	1
unknown	0

Top tissues across cohort

Tissue	Cohort genes
bone marrow	1
bone marrow cell	1
trabecular bone tissue	1

Per-gene tissue summary (top 30)

Symbol	Bgee breadth	FANTOM5 breadth	SCXA	Top tissues
HMBS	271	ubiquitous	marker	trabecular bone tissue, bone marrow, bone marrow cell

Protein interactions among cohort

Intra-cohort edges: 0.

Hub genes (top 10 by interactor count)

Symbol	Interactor count
HMBS	44

Structural data

PDB: 1 · AlphaFold-only: 0 · No structure: 0

Cohort genes with PDB structures (top 30)

Symbol	UniProt	PDB entries
HMBS	P08397	11

Function

Pathway analysis

Distinct Reactome pathways touched by cohort: 1. Enrichment computed across 1 evidence-associated genes (1 with Reactome annotation).

Pathways by enrichment

Over-representation of cohort genes vs the genome-wide background (hypergeometric test, Benjamini-Hochberg FDR; fold = observed/expected over 1 annotated cohort genes). Counts and members are kept as ground-truth; sorted by enrichment.

Pathway	Cohort genes	Fold	FDR	Sample cohort genes
Heme biosynthesis	1	761.3×	0.001	HMBS

GO biological processes by enrichment

Over-representation of cohort genes vs the genome-wide background (hypergeometric test, Benjamini-Hochberg FDR; fold = observed/expected over 1 annotated cohort genes). Counts and members are kept as ground-truth; sorted by enrichment.

GO term	Cohort genes	Fold	FDR	Sample cohort genes
obsolete protoporphyrinogen IX biosynthetic process	1	1685.2×	9e-04	HMBS
heme B biosynthetic process	1	1685.2×	9e-04	HMBS
heme A biosynthetic process	1	1532.0×	9e-04	HMBS
heme biosynthetic process	1	601.9×	0.002	HMBS

Therapeutics

Drug target analysis

Approved (phase 4): 0 · Phase ≥3: 0 · Phased (≥1): 0 · Undrugged: 1

Druggability breadth: 1 of 1 evidence-associated genes (100%) have a ChEMBL target (buckets above are over the deeply-mined display cohort).

Top cohort targets by molecule count

Symbol	Molecules	Max phase
HMBS	0	0

Bioactivity and enzyme data

Enzyme cohort genes (≥1 EC): 1.

Cohort genes with ChEMBL bioactivity (full, sorted by assay count)

Symbol	Assays	Type breakdown
HMBS	3	Binding:3

Cohort enzymes (BRENDA EC)

Symbol	EC numbers	Names
HMBS	2.5.1.61	hydroxymethylbilane synthase

Pharmacogenomics

Cohort genes with a PharmGKB record: 1; with CPIC/DPWG dosing guidelines: 0.

No cohort gene has a CPIC/DPWG genotype-guided dosing guideline (PharmGKB).

Chemical tractability of cohort targets

0 approved/phased compounds have measured bioactivity against a cohort gene (and aren’t yet in disease-level trials). This is a research / tractability signal, NOT a therapeutic recommendation — a bioactivity row often reflects off-target or screening binding (e.g. promiscuous kinase inhibitors against a cohort kinase), implying no disease mechanism.

Druggability pyramid

Cohort genes binned by druggability tier (high → low):

Tier	Definition	Genes	Symbols
A	Approved (phase 4 drug)	0
B	Phased (≥1) drug, not yet approved	0
C	Druggable family + PDB, no drug	1	HMBS
D	Druggable family + AlphaFold only, no drug	0
E	Difficult family or no structure, no drug	0

Undrugged target profiles

1 cohort genes are undrugged. Ranked by ‘starting-point quality’ (assay depth + drugged-partner adjacency).

Symbol	ChEMBL assays	Drugged partners (top 3)
HMBS	3	—

Clinical trials & evidence

Clinical trials

Clinical trials: 0.