Genetic Variant HMBS:c.33+135dupT (chr11-119085172-C-CT) – ACMG Classification: Benign (-8 pts)

Variant summary

Our verdict is Benign. The variant received -8 ACMG points: 0P and 8B. BS1BS2

The NM_000190.4(HMBS):c.33+135dupT variant causes a intron change involving the alteration of a non-conserved nucleotide. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: 𝑓 0.0039 ( 11 hom., cov: 0)

Exomes 𝑓: 0.0061 ( 34 hom. )

Consequence

HMBS
NM_000190.4 intron

Scores

Not classified

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -0.497

Publications

0 publications found

Variant links:

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]

HMBS Gene-Disease associations (from GenCC):

acute intermittent porphyria
Inheritance: SD, AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Orphanet

HMBS links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -8 ACMG points.

BS1

Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00386 (258/66784) while in subpopulation AFR AF = 0.00565 (104/18394). AF 95% confidence interval is 0.00477. There are 11 homozygotes in GnomAd4. There are 118 alleles in the male GnomAd4 subpopulation. Median coverage is 0. This position passed quality control check.

BS2

High AC in GnomAd4 at 258 SD,AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HMBS	NM_000190.4 link	c.33+135dupT		intron_variant	Intron 1 of 13	ENST00000652429.1	NP_000181.2	P08397-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
HMBS	ENST00000652429.1 link	c.33+106_33+107insT		intron_variant	Intron 1 of 13		NM_000190.4	ENSP00000498786.1		P08397-1

Frequencies

GnomAD3 genomes

AF:

0.00387

AC:

258

AN:

66748

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00566

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00418

Gnomad ASJ

AF:

0.0117

Gnomad EAS

AF:

0.000713

Gnomad SAS

AF:

0.000762

Gnomad FIN

AF:

0.000888

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00282

Gnomad OTH

AF:

0.00469

GnomAD4 exome

AF:

0.00605

AC:

4423

AN:

730766

Hom.:

Cov.:

AF XY:

0.00610

AC XY:

2204

AN XY:

361404

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00278

AC:

AN:

18364

American (AMR)

AF:

0.0226

AC:

264

AN:

11692

Ashkenazi Jewish (ASJ)

AF:

0.00706

AC:

AN:

10342

East Asian (EAS)

AF:

0.00758

AC:

AN:

7780

South Asian (SAS)

AF:

0.00808

AC:

403

AN:

49848

European-Finnish (FIN)

AF:

0.00914

AC:

103

AN:

11268

Middle Eastern (MID)

AF:

0.00471

AC:

AN:

1910

European-Non Finnish (NFE)

AF:

0.00555

AC:

3287

AN:

592020

Other (OTH)

AF:

0.00632

AC:

174

AN:

27542

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.370

Heterozygous variant carriers

197

393

590

786

983

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

122

244

366

488

610

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.00386

AC:

258

AN:

66784

Hom.:

Cov.:

AF XY:

0.00400

AC XY:

118

AN XY:

29534

show subpopulations

African (AFR)

AF:

0.00565

AC:

104

AN:

18394

American (AMR)

AF:

0.00417

AC:

AN:

4792

Ashkenazi Jewish (ASJ)

AF:

0.0117

AC:

AN:

2142

East Asian (EAS)

AF:

0.000712

AC:

AN:

1404

South Asian (SAS)

AF:

0.000765

AC:

AN:

1308

European-Finnish (FIN)

AF:

0.000888

AC:

AN:

1126

Middle Eastern (MID)

AF:

0.00

AC:

AN:

European-Non Finnish (NFE)

AF:

0.00282

AC:

102

AN:

36226

Other (OTH)

AF:

0.00466

AC:

AN:

858

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.505

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Genome Hom

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

-0.50

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

Details are displayed if max score is > 0.2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over