chr1-3857638-C-G

Variant names:

• chr1-3857638-C-G
• NM_004402.4:c.35C>G

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_004402.4(DFFB):​c.35C>G​(p.Ala12Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 15/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 34)
• Consequence: DFFB NM_004402.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.23
• Publications: 0 publications found

Genes affected

DFFB (HGNC:2773): (DNA fragmentation factor subunit beta) Apoptosis is a cell death process that removes toxic and/or useless cells during mammalian development. The apoptotic process is accompanied by shrinkage and fragmentation of the cells and nuclei and degradation of the chromosomal DNA into nucleosomal units. DNA fragmentation factor (DFF) is a heterodimeric protein of 40-kD (DFFB) and 45-kD (DFFA) subunits. DFFA is the substrate for caspase-3 and triggers DNA fragmentation during apoptosis. DFF becomes activated when DFFA is cleaved by caspase-3. The cleaved fragments of DFFA dissociate from DFFB, the active component of DFF. DFFB has been found to trigger both DNA fragmentation and chromatin condensation during apoptosis. Alternatively spliced transcript variants encoding distinct isoforms have been found for this gene but the biological validity of some of these variants has not been determined. [provided by RefSeq, Sep 2013]

CEP104 (HGNC:24866): (centrosomal protein 104) This gene encodes a centrosomal protein required for ciliogenesis and for ciliary tip structural integrity. The mammalian protein contains three amino-terminal hydrophobic domains, two glycosylation sites, four cysteine-rich motifs, and two regions with homology to the glutamate receptor ionotropic, NMDA 1 protein. During ciliogenesis, the encoded protein translocates from the distal tips of the centrioles to the tip of the elongating cilium. Knockdown of the protein in human retinal pigment cells results in severe defects in ciliogenesis with structural deformities at the ciliary tips. Allelic variants of this gene are associated with the autosomal-recessive disorder Joubert syndrome, which is characterized by a distinctive mid-hindbrain and cerebellar malformation, oculomotor apraxia, irregular breathing, developmental delay, and ataxia. [provided by RefSeq, Feb 2016]

CEP104 Gene-Disease associations (from GenCC):

• Joubert syndrome 25

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: G2P, Labcorp Genetics (formerly Invitae), Ambry Genetics
• Joubert syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.11582735).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
DFFB	NM_004402.4	c.35C>G	p.Ala12Gly	missense_variant	Exon 1 of 7	ENST00000378209.8	NP_004393.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DFFB	ENST00000378209.8	c.35C>G	p.Ala12Gly	missense_variant	Exon 1 of 7	1	NM_004402.4	ENSP00000367454.4

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Oct 24, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.35C>G (p.A12G) alteration is located in exon 1 (coding exon 1) of the DFFB gene. This alteration results from a C to G substitution at nucleotide position 35, causing the alanine (A) at amino acid position 12 to be replaced by a glycine (G). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.13
BayesDel_addAF	Benign	-0.28	T
BayesDel_noAF	Benign	-0.64
CADD	Benign	17
DANN	Uncertain	1.0
DEOGEN2	Benign	0.031	T;T;T;.
Eigen	Benign	-0.33
Eigen_PC	Benign	-0.26
FATHMM_MKL	Benign	0.038	N
LIST_S2	Benign	0.62	T;T;T;T
M_CAP	Benign	0.029	D
MetaRNN	Benign	0.12	T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.8	.;.;L;.
PhyloP100		1.2
PrimateAI	Benign	0.45	T
PROVEAN	Benign	-1.1	.;N;N;N
REVEL	Benign	0.072
Sift	Benign	0.28	.;T;T;T
Sift4G	Benign	0.29	T;T;T;T
Polyphen		0.12	.;B;B;.
Vest4		0.090
MutPred		0.44		Loss of stability (P = 0.038);Loss of stability (P = 0.038);Loss of stability (P = 0.038);Loss of stability (P = 0.038);
MVP		0.37
MPC		0.40
ClinPred		0.50	D
GERP RS		4.3
PromoterAI		0.14	Neutral
Varity_R		0.24
gMVP		0.38
Mutation Taster		=89/11	polymorphism

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

hg19: chr1-3774202;