Variant 6-25097070-C-T details in Genebe, Genetics Data Aggregator

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2BP4_Moderate

The NR_002174.2(CMAHP):n.1141G>A variant causes a non coding transcript exon change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000633 in 315,980 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000063 ( 0 hom. )

Consequence

CMAHP
NR_002174.2 non_coding_transcript_exon

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 3.17

Variant links:

Genes affected

CMAHP (HGNC:2098): (cytidine monophospho-N-acetylneuraminic acid hydroxylase, pseudogene) Sialic acids are terminal components of the carbohydrate chains of glycoconjugates involved in ligand-receptor, cell-cell, and cell-pathogen interactions. The two most common forms of sialic acid found in mammalian cells are N-acetylneuraminic acid (Neu5Ac) and its hydroxylated derivative, N-glycolylneuraminic acid (Neu5Gc). Studies of sialic acid distribution show that Neu5Gc is not detectable in normal human tissues although it was an abundant sialic acid in other mammals. Neu5Gc is, in actuality, immunogenic in humans. The absense of Neu5Gc in humans is due to a deletion within the human gene CMAH encoding cytidine monophosphate-N-acetylneuraminic acid hydroxylase, an enzyme responsible for Neu5Gc biosynthesis. Sequences encoding the mouse, pig, and chimpanzee hydroxylase enzymes were obtained by cDNA cloning and found to be highly homologous. However, the homologous human cDNA differs from these cDNAs by a 92-bp deletion in the 5' region. This deletion, corresponding to exon 6 of the mouse hydroxylase gene, causes a frameshift mutation and premature termination of the polypeptide chain in human. It seems unlikely that the truncated human hydroxylase mRNA encodes for an active enzyme explaining why Neu5Gc is undetectable in normal human tissues. Human genomic DNA also shows evidence of this deletion which does not occur in the genomes of African great apes. Nonetheless, the CMAH gene maps to 6p21.32 in humans and great apes indicating that mutation of the CMAH gene occurred following human divergence from chimpanzees and bonobos. [provided by RefSeq, Jul 2008]

CMAHP links:

(HGNC:):

links:

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ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 0 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.38).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CMAHP	NR_002174.2 linkuse as main transcript	n.1141G>A		non_coding_transcript_exon_variant	8/13

Ensembl

Gene	Transcript	HGVSc	Effect	#exon/exons	TSL
CMAHP	ENST00000377993.8 linkuse as main transcript	n.1149G>A	non_coding_transcript_exon_variant	9/14	1
	ENST00000643807.1 linkuse as main transcript	n.1505G>A	non_coding_transcript_exon_variant	11/16
	ENST00000648291.1 linkuse as main transcript	n.392+18359C>T	intron_variant, non_coding_transcript_variant

Frequencies

GnomAD3 genomes

Cov.:

GnomAD3 exomes

AF:

0.0000134

AC:

AN:

149444

Hom.:

AF XY:

0.00

AC XY:

AN XY:

80184

show subpopulations

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 SAS exome

AF:

0.0000916

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000633

AC:

AN:

315980

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

178600

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000340

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.38

CADD

Benign

DANN

Uncertain

0.99

Splicing

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Computational scores

Splicing

Publications

LitVar

Other links and lift over