Genetic Variant HMBS:c.33+134_33+135dupTT (chr11-119085172-C-CTT) – 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+134_33+135dupTT 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 0.0012 ( 6 hom., cov: 0)

Exomes 𝑓: 0.0037 ( 96 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:

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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 = 0.00124 (83/66804) while in subpopulation AFR AF = 0.0037 (68/18402). AF 95% confidence interval is 0.00299. There are 6 homozygotes in GnomAd4. There are 38 alleles in the male GnomAd4 subpopulation. Median coverage is 0. This position passed quality control check.

BS2

High AC in GnomAd4 at 83 SD,AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
HMBS	NM_000190.4 link	c.33+134_33+135dupTT		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+107insTT		intron_variant	Intron 1 of 13		NM_000190.4	ENSP00000498786.1		P08397-1

Frequencies

GnomAD3 genomes

AF:

0.00124

AC:

AN:

66768

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00370

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000626

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000304

Gnomad OTH

AF:

0.00117

GnomAD4 exome

AF:

0.00374

AC:

2733

AN:

731304

Hom.:

Cov.:

AF XY:

0.00369

AC XY:

1334

AN XY:

361734

show subpopulations

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

African (AFR)

AF:

0.00294

AC:

AN:

18364

American (AMR)

AF:

0.00976

AC:

115

AN:

11780

Ashkenazi Jewish (ASJ)

AF:

0.00319

AC:

AN:

10346

East Asian (EAS)

AF:

0.0120

AC:

AN:

7770

South Asian (SAS)

AF:

0.00589

AC:

294

AN:

49918

European-Finnish (FIN)

AF:

0.00841

AC:

AN:

11294

Middle Eastern (MID)

AF:

0.00260

AC:

AN:

1920

European-Non Finnish (NFE)

AF:

0.00327

AC:

1935

AN:

592382

Other (OTH)

AF:

0.00396

AC:

109

AN:

27530

⚠️ 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: 0.389

Heterozygous variant carriers

113

225

338

450

563

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

112

168

224

280

<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:

0.00124

AC:

AN:

66804

Hom.:

Cov.:

AF XY:

0.00129

AC XY:

AN XY:

29542

show subpopulations

African (AFR)

AF:

0.00370

AC:

AN:

18402

American (AMR)

AF:

0.000626

AC:

AN:

4796

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

2142

East Asian (EAS)

AF:

0.00

AC:

AN:

1404

South Asian (SAS)

AF:

0.00

AC:

AN:

1308

European-Finnish (FIN)

AF:

0.00

AC:

AN:

1126

Middle Eastern (MID)

AF:

0.00

AC:

AN:

European-Non Finnish (NFE)

AF:

0.000304

AC:

AN:

36234

Other (OTH)

AF:

0.00117

AC:

AN:

858

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.562

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

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

Publications

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11-119085172-CTTTTTTTTTTTTTTTTTTTTTT-CTTTTTTTTTTTTTTTTTTTTTTTT

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