ClinGen Dosage Sensitivity Curation Page

HMBS

  • Curation Status: Complete

Location Information

  • 11q23.3
  • GRCh37/hg19 chr11: 118,955,587-118,964,259
  • View: NCBI | Ensembl | UCSC
  • GRCh38/hg38 chr11: 119,084,864-119,093,549
  • View: NCBI | Ensembl | UCSC
Select assembly: (NC_000011.9) (NC_000011.10)
Evidence for haploinsufficiency phenotype
PubMed ID Description
19460837 Whatley et al. studied 467 unrelated patients with proven or putative porphyria. Amongst 123 different HMBS mutations detected by sequencing or qPCR were four multi-exon deletions: exons 3-15, 3-4, 9-15, and 3-11. Article associated with porphyria and hepatocellular carcinoma PMID: 23344888 Sardh et al. studied the incidence of primary liver cancer and clinical characteristics in a cohort of 179 acute porphyria patients above the age of 50 years. Out of 20 acute intermittent porphyria patients with hepatocellular carcinoma (HCC), 18 patients had nonsense, frameshift or splice variants. W198X was the most common variant in this cohort. It was found in 9 patients. The other reported variants were: c.826-2A>G, c.499-1G>A, c.345-2A>G, c.88-2A>G, c.207delT.
12372055 Floderus et al. studied patients with acute intermittent porphyria (AIP). HMBS mutations were detected by DGGE and confirmed by sequencing. A wide mutation spectrum was reported, including: an M1 variant, nonsense variants (in exons 4, 10, and 12), several canonical splice site variants, and several frameshift variants. Article associated with porphyria and hepatocellular carcinoma PMID: 25445397 Xiaoye Schneider-Yin et al. studied 1 patient with two variants in HMBS gene. A 68-year old Swiss female was diagnosed as an asymptomatic carrier of germline mutation p.G111R variant in the HMBS gene was known in her family with AIP. She had never experienced an acute porphyric attack and her urinary PBG concentrations were only slightly above the normal range. She had two solid lesions of 1.7 cm and 2.7 cm, highly suspicious of HCC, in liver. Authors detected a second somatic variant, only in the cancerous tissue i.e. p.L220X in the HMBS gene of this patient, located in trans to the respective germline mutation.
10790212 di Montemuros et al. report seven mutations in eight patients with AIP (biochemically confirmed) detected by DGGE and sequencing: two splicing variants, three frameshift variants, and two nonsense variants.

Haploinsufficiency phenotype comments:

Haploinsufficiency of the HMBS gene causes acute intermittent porphyria. Haploinsufficiency of the HMBS gene also causes HCC in patients above age 50 with incidence rates range from 0.16 to 0.35% according to the populations studied.

  • Triplosensitivity score: 0
  • Strength of Evidence (disclaimer): No evidence for dosage pathogenicity

Triplosensitivity phenotype comment:

No duplications involving only the entire HMBS gene reported