chr7-100101771-CTG-C

Position:

• chr7-100101771-CTG-C

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_004722.4(AP4M1):​c.58+1_58+2del variant causes a splice donor, coding sequence change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000199 in 1,507,784 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: 𝑓 0.000014 (0 hom., cov: 33)
  • Exomes 𝑓: 7.3e-7 (0 hom.)
• Consequence: AP4M1 NM_004722.4 splice_donor, coding_sequence
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.27

Genes affected

AP4M1 (HGNC:574): (adaptor related protein complex 4 subunit mu 1) This gene encodes a subunit of the heterotetrameric AP-4 complex. The encoded protein belongs to the adaptor complexes medium subunits family. This AP-4 complex is involved in the recognition and sorting of cargo proteins with tyrosine-based motifs from the trans-golgi network to the endosomal-lysosomal system. [provided by RefSeq, Jul 2008]

MCM7 (HGNC:6950): (minichromosome maintenance complex component 7) The protein encoded by this gene is one of the highly conserved mini-chromosome maintenance proteins (MCM) that are essential for the initiation of eukaryotic genome replication. The hexameric protein complex formed by the MCM proteins is a key component of the pre-replication complex (pre_RC) and may be involved in the formation of replication forks and in the recruitment of other DNA replication related proteins. The MCM complex consisting of this protein and MCM2, 4 and 6 proteins possesses DNA helicase activity, and may act as a DNA unwinding enzyme. Cyclin D1-dependent kinase, CDK4, is found to associate with this protein, and may regulate the binding of this protein with the tumorsuppressor protein RB1/RB. Alternatively spliced transcript variants encoding distinct isoforms have been reported. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-100101771-CTG-C is Pathogenic according to our data. Variant chr7-100101771-CTG-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1493893.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
AP4M1	NM_004722.4	c.58+1_58+2del		splice_donor_variant, coding_sequence_variant	1/15	ENST00000359593.9	NP_004713.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
AP4M1	ENST00000359593.9	c.58+1_58+2del		splice_donor_variant, coding_sequence_variant	1/15	1	NM_004722.4	ENSP00000352603	P3

Frequencies

GnomAD3 genomes AF: 0.0000138 AC: 2 AN: 145114 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000503

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 7.34e-7 AC: 1 AN: 1362670 Hom.: 0 AF XY: 0.00000148 AC XY: 1 AN XY: 677716

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: 0.0000117

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000138 AC: 2 AN: 145114 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 70650

Gnomad4 AFR AF: 0.0000503

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hereditary spastic paraplegia 50 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 13, 2023

This sequence change affects a splice site in intron 1 of the AP4M1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in AP4M1 are known to be pathogenic (PMID: 24700674, 25496299, 25558065). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with AP4M1-related conditions. ClinVar contains an entry for this variant (Variation ID: 1493893). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.94		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.94		Position offset: 1

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

Publications

LitVar

Other links and lift over

dbSNP: rs1796054104; hg19: chr7-99699394;