chr3-15645288-G-C

Variant names:

• chr3-15645288-G-C
• rs181396238
• NM_001370658.1:c.1372G>C

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_001370658.1(BTD):​c.1372G>C​(p.Ala458Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000616 in 1,461,884 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A458T) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000062 (0 hom.)
• Consequence: BTD NM_001370658.1 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.87
• Publications: 1 publications found

Genes affected

BTD (HGNC:1122): (biotinidase) The protein encoded by this gene functions to recycle protein-bound biotin by cleaving biocytin (biotin-epsilon-lysine), a normal product of carboxylase degradation, resulting in regeneration of free biotin. The encoded protein has also been shown to have biotinyl transferase activity. Mutations in this gene are associated with biotinidase deficiency. Multiple transcript variants encoding different isoforms have been described. [provided by RefSeq, Aug 2013]

BTD Gene-Disease associations (from GenCC):

• biotinidase deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Myriad Women’s Health, ClinGen, Orphanet, Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae)
• Leigh syndrome

  Inheritance: AR Classification: MODERATE Submitted by: ClinGen

ACMG classification

Our verdict: Pathogenic. The variant received 19 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_001370658.1
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-15645288-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 25108.
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 88 curated pathogenic missense variants (we use a threshold of 10). The gene has 9 curated benign missense variants. Gene score misZ: -0.52516 (below the threshold of 3.09). Trascript score misZ: 0.15371 (below the threshold of 3.09). GenCC associations: The gene is linked to Leigh syndrome, biotinidase deficiency.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.965
• PP5: Variant 3-15645288-G-C is Pathogenic according to our data. Variant chr3-15645288-G-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 25089.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001370658.1. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BTD	NM_001370658.1	MANE Select	c.1372G>C	p.Ala458Pro	missense	Exon 4 of 4	NP_001357587.1
	BTD	NM_001281723.4		c.1372G>C	p.Ala458Pro	missense	Exon 4 of 4	NP_001268652.2
	BTD	NM_001281724.3		c.1372G>C	p.Ala458Pro	missense	Exon 6 of 6	NP_001268653.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	BTD	ENST00000643237.3	MANE Select	c.1372G>C	p.Ala458Pro	missense	Exon 4 of 4	ENSP00000495254.2
	BTD	ENST00000303498.10	TSL:1	c.1372G>C	p.Ala458Pro	missense	Exon 5 of 5	ENSP00000306477.6
	BTD	ENST00000427382.2	TSL:4	c.1372G>C	p.Ala458Pro	missense	Exon 4 of 4	ENSP00000397113.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.0000159 AC: 4 AN: 251444 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000616 AC: 9 AN: 1461884 Hom.: 0 Cov.: 31 AF XY: 0.00000550 AC XY: 4 AN XY: 727248

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.0000927 AC: 8 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112006

Other (OTH) AF: 0.0000166 AC: 1 AN: 60396

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Biotinidase deficiency Pathogenic:3

Feb 02, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 478 of the BTD protein (p.Ala478Pro). This variant is present in population databases (rs181396238, gnomAD 0.01%). This missense change has been observed in individual(s) with biotinidase deficiency (PMID: 19757147). ClinVar contains an entry for this variant (Variation ID: 25089). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt BTD protein function with a positive predictive value of 95%. This variant disrupts the p.Ala478 amino acid residue in BTD. Other variant(s) that disrupt this residue have been observed in individuals with BTD-related conditions (PMID: 26810761), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic.

Jul 03, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: BTD c.1372G>C (p.Ala458Pro) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 1.6e-05 in 251444 control chromosomes. c.1372G>C has been reported in the literature as biallelic homozygous or compound heterozygous genotypes in individuals affected with Biotinidase Deficiency (example, Sarafoglou_2009, Sharma_2024). These data indicate that the variant is likely to be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in <10% of normal activity in an individual with a homozygous genotype (Sarafoglou_2009). The following publications have been ascertained in the context of this evaluation (PMID: 36684547, 20556795, 19757147, 38299772). ClinVar contains an entry for this variant (Variation ID: 25089). Based on the evidence outlined above, the variant was classified as pathogenic.

Feb 07, 2024

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not provided Pathogenic:1

Mar 24, 2022

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 19757147)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.51
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D
Eigen	Pathogenic	0.84
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Benign	0.83	T
M_CAP	Pathogenic	0.31	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.1	M
PhyloP100		7.9
PrimateAI	Uncertain	0.56	T
PROVEAN	Pathogenic	-4.6	D
REVEL	Pathogenic	0.93
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0030	D
Polyphen		1.0	D
Vest4		0.94
MutPred		0.77		Loss of helix (P = 0.0558)
MVP		1.0
MPC		0.47
ClinPred		0.98	D
GERP RS		5.6
Varity_R		0.85
gMVP		0.96
Mutation Taster		=2/98	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs181396238; hg19: chr3-15686795;