chr11-119085041-GTAACGGCAATGCGGCTGCAACGGCGGTGAGTGCTGA-G

Position:

• chr11-119085041-GTAACGGCAATGCGGCTGCAACGGCGGTGAGTGCTGA-G

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_000190.4(HMBS):​c.9_33+11del variant causes a splice donor, splice donor 5th base, coding sequence, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: HMBS NM_000190.4 splice_donor, splice_donor_5th_base, coding_sequence, intron
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.51

Genes affected

HMBS (HGNC:4982): (hydroxymethylbilane synthase) This gene encodes a member of the hydroxymethylbilane synthase superfamily. The encoded protein is the third enzyme of the heme biosynthetic pathway and catalyzes the head to tail condensation of four porphobilinogen molecules into the linear hydroxymethylbilane. Mutations in this gene are associated with the autosomal dominant disease acute intermittent porphyria. Alternatively spliced transcript variants encoding different isoforms have been described. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.17034991 fraction of the gene. Cryptic splice site detected, with MaxEntScore 3.3, offset of -21, new splice context is: ccgGTgacc. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 11-119085041-GTAACGGCAATGCGGCTGCAACGGCGGTGAGTGCTGA-G is Pathogenic according to our data. Variant chr11-119085041-GTAACGGCAATGCGGCTGCAACGGCGGTGAGTGCTGA-G is described in ClinVar as [Pathogenic]. Clinvar id is 3254787.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
HMBS	NM_000190.4	c.9_33+11del		splice_donor_variant, splice_donor_5th_base_variant, coding_sequence_variant, intron_variant	1/14	ENST00000652429.1	NP_000181.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
HMBS	ENST00000652429.1	c.9_33+11del		splice_donor_variant, splice_donor_5th_base_variant, coding_sequence_variant, intron_variant	1/14		NM_000190.4	ENSP00000498786	P3

Frequencies

GnomAD3 genomes Cov.: 31

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Acute intermittent porphyria Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Jul 17, 2023

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with acute intermittent porphyria (AIP; MIM#176000). (I) 0107 - This gene is associated with autosomal dominant disease. (I) 0112 - The condition associated with this gene has incomplete penetrance. AIP is a disease with low clinical penetrance, with hormonal changes and commonly used drugs as triggering factors (PMIDs: 33445488, 27539938). (I) 0211 - Canonical splice site variant without proven consequence on splicing (no functional evidence available). (SP) 0251 - This variant is heterozygous. (I) 0301 - Variant is absent from gnomAD (both v2 and v3). (SP) 0505 - Abnormal splicing is predicted by in silico tools and affected nucleotide is highly conserved. (SP) 0701 - Other variants comparable to the one identified in this case have very strong previous evidence for pathogenicity. Multiple variants affecting the same canonical splice donor site, as well as other variants affecting non-canonical nucleotides in the same region, have been reported in patients with acute intermittent porphyria (PMIDs: 31044425, 17298216) . (SP) 0807 - This variant has no previous evidence of pathogenicity. (I) 0905 - No published segregation evidence has been identified for this variant. (I) 1007 - No published functional evidence has been identified for this variant. (I) 1101 - Very strong and specific phenotype match for this individual. (SP) 1206 - This variant has been shown to be paternally inherited (by trio analysis). (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

Computational scores

Source: dbNSFP v4.3

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr11-118955751;