Criteria Specification Registry

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Criteria Specification

ClinGen Cerebral Creatine Deficiency Syndromes Expert Panel Specifications to the ACMG/AMP Variant Interpretation Guidelines for SLC6A8 Version 1

Description : Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel ACMG Classification Rules Specified for Solute Carrier Family 6, Member 8 (SLC6A8; Creatine Transporter) Summary of ACMG-AMP Criteria for SLC6A8 Variants

Version : 1.0.0

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Cerebral Creatine Deficiency Syndromes VCEP

Released

3/21/2022

05:00:00

Rules for SLC6A8

Gene: SLC6A8 (HGNC:11055) HGNC Name: solute carrier family 6 member 8 Transcripts: NM_005629.4 Disease: creatine transporter deficiency (MONDO:0010305)

Criteria & Strength Specifications
PVS1 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Null variant (nonsense, frameshift, canonical +/−1 or 2 splice sites, initiation codon, single or multi-exon deletion) in a gene where loss of function (LOF) is a known mechanism of disease. Caveats: • Beware of genes where LOF is not a known disease mechanism (e.g. GFAP, MYH7). • Use caution interpreting LOF variants at the extreme 3’ end of a gene. • Use caution with splice variants that are predicted to lead to exon skipping but leave the remainder of the protein intact. • Use caution in the presence of multiple transcripts. Stand Alone Very Strong Loss of function is a known mechanism of disease for Creatine Transporter Deficiency. Specifications are based on the decision tree as outlined in Tayoun etal, 2018 (Hum Mutat. 2018 Nov;39(11):1517-1524; PMID: 30192042) SLC6A8: PVS1 is applicable as described in Abou Tayoun et al, 2018 (PMID: 30192042) Modification Type: None Strong Moderate Supporting Not Applicable
PS1 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Same amino acid change as a previously established pathogenic variant regardless of nucleotide change. Example: Val->Leu caused by either G>C or G>T in the same codon. Caveat: Beware of changes that impact splicing rather than at the amino acid/protein level. Stand Alone Very Strong Strong PS1 is applicable as described. Modification Type: None Moderate Supporting Not Applicable
PS2 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary De novo (both maternity and paternity confirmed) in a patient with the disease and no family history. Note: Confirmation of paternity only is insufficient. Egg donation, surrogate motherhood, errors in embryo transfer, etc. can contribute to non-maternity. Stand Alone Very Strong Strong Note: Confirmation of paternity in females only is insufficient. Egg donation, surrogate motherhood, errors in embryo transfer, etc. can contribute to non-maternity Modification Type: None Moderate Newly hemizygous male with variant identified in mother. Modification Type: Strength,Disease-specific Supporting Not Applicable
PS3 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Well-established in vitro or in vivo functional studies supportive of a damaging effect on the gene or gene product. Note: Functional studies that have been validated and shown to be reproducible and robust in a clinical diagnostic laboratory setting are considered the most well-established. Stand Alone Very Strong Strong RT-PCR evidence of mis-splicing for non-canonical intronic variants For non-canonical splicing variants, RT-PCR evidence demonstrating transcripts of alternative length or specific intron or exon inclusion/exclusion. These studies can be performed in patient derived cells, by placing the mutant genomic DNA into plasmid vectors, or by over-expressing mutant transcript. Assays should demonstrate defective splicing with RT-PCR analysis or RNA sequencing to confirm alternative transcripts. Modification Type: Disease-specific Moderate Supporting Creatine transport activity <10% wild type with less than or equal to 125uM creatine used in SLC6A8 deficient fibroblasts RT-PCR evidence of mis-splicing for non-canonical intronic variants with evidence of normal splice products. For non-canonical splicing variants, RT-PCR evidence demonstrating transcripts of alternative length or specific intron or exon inclusion/exclusion. These studies can be performed in patient derived cells, by placing the mutant genomic DNA into plasmid vectors, or by over-expressing mutant transcript. Assays should demonstrate defective splicing with RT-PCR analysis or RNA sequencing to confirm alternative transcripts. Modification Type: Disease-specific Not Applicable
PS4 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary The prevalence of the variant in affected individuals is significantly increased compared to the prevalence in controls. Note 1: Relative risk (RR) or odds ratio (OR), as obtained from case-control studies, is >5.0 and the confidence interval around the estimate of RR or OR does not include 1.0. See manuscript for detailed guidance. Note 2: In instances of very rare variants where case-control studies may not reach statistical significance, the prior observation of the variant in multiple unrelated patients with the same phenotype, and its absence in controls, may be used as moderate level of evidence. Stand Alone Very Strong 4 independent male probands with elevated urine creatine/creatinine ratio on one occasion at minimum, in addition to any proband used for PP4. Variant must meet PM2_Supporting criterion for PS4 to apply. Modification Type: Strength Strong 3 independent male probands with elevated urine creatine/creatinine ratio on one occasion at minimum, in addition to any proband used for PP4. Variant must meet PM2_Supporting criterion for PS4 to apply. Modification Type: Disease-specific Moderate 2 independent male probands with elevated urine creatine/creatinine ratio on one occasion at minimum, in addition to any proband used for PP4. Variant must meet PM2_Supporting criterion for PS4 to apply. Modification Type: Strength Supporting One independent male proband in addition to any proband used for PP4. Modification Type: Strength Not Applicable
PM1 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Located in a mutational hot spot and/or critical and well-established functional domain (e.g. active site of an enzyme) without benign variation. Stand Alone Very Strong Strong Moderate Supporting Not Applicable Comments: Not applicable
PM2 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes or Exome Aggregation Consortium. Caveat: Population data for indels may be poorly called by next generation sequencing. Stand Alone Very Strong Strong Moderate Supporting Absent/rare from controls in an ethnically-matched cohort population sample. Threshold: <0.00002 (0.002%) AND 0 hemizygotes in gnomAD. Modification Type: Disease-specific Not Applicable
PM3 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary For recessive disorders, detected in trans with a pathogenic variant Note: This requires testing of parents (or offspring) to determine phase. Stand Alone Very Strong Strong Moderate Supporting Not Applicable Comments: SLC6A8 is an X-linked gene, therefore PM3 is not applicable
PM4 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Protein length changes due to in-frame deletions/insertions in a non-repeat region or stop-loss variants. Stand Alone Very Strong Strong Moderate Protein length changes due to in-frame deletions/insertions in a non-repeat region or stop-loss variants. Modification Type: None Supporting Not Applicable
PM5 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Novel missense change at an amino acid residue where a different missense change determined to be pathogenic has been seen before. Example: Arg156His is pathogenic; now you observe Arg156Cys. Caveat: Beware of changes that impact splicing rather than at the amino acid/protein level. Stand Alone Very Strong Strong Moderate Missense change at an amino acid residue where a different missense change determined to be pathogenic has been seen before. Modification Type: None Supporting Missense change at an amino acid residue where a different missense change determined to be likely pathogenic has been seen before. Modification Type: Strength Not Applicable
PM6 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Assumed de novo, but without confirmation of paternity and maternity. Stand Alone Very Strong Strong Moderate Supporting Not Applicable
PP1 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Co-segregation with disease in multiple affected family members in a gene definitively known to cause the disease. Note: May be used as stronger evidence with increasing segregation data. Stand Alone Very Strong Strong 3 affected segregations + 0 unaffected segregations OR 2 affected segregations + 3 unaffected segregations Modification Type: Strength Moderate 2 affected segregations + 0 unaffected segregations. Modification Type: Strength Supporting 1 affected family member + 3 unaffected segregations. Modification Type: Disease-specific Not Applicable
PP2 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Missense variant in a gene that has a low rate of benign missense variation and where missense variants are a common mechanism of disease. Stand Alone Very Strong Strong Moderate Supporting Not Applicable Comments: Not applicable, gnomAD (01/2019) expected missense 243.5, observed missense 117, for Z=2.94 (o/e =0.48). No constraint against missense variation.
PP3 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Multiple lines of computational evidence support a deleterious effect on the gene or gene product (conservation, evolutionary, splicing impact, etc.). Caveat: As many in silico algorithms use the same or very similar input for their predictions, each algorithm should not be counted as an independent criterion. PP3 can be used only once in any evaluation of a variant. Stand Alone Very Strong Strong Moderate Supporting REVEL score >0.75 for missense variants In frame deletion or insertion predicted deleterious by PROVEAN, MutPred indel, and MutationTaster. Predicted impact on splicing by SpliceAI and varSEAK. Modification Type: None Not Applicable
PP4 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Patient’s phenotype or family history is highly specific for a disease with a single genetic etiology. Stand Alone Very Strong Strong See points scheme in main document 4 or more points are required for PP4_Strong; two or more data types must be available to apply PP4_Strong, full sequencing of SLC6A8, including all coding exons and intron/exon boundaries, must have been carried out. If not, consider downgrading. For PP4, assign points for each type of data present, and then add up the points. PP4 = 1-2 points, PP4_Moderate = 3 points, PP4_Strong = 4 points Two or more data types are recommended to reach moderate and required to reach strong. An individual used to assign PP4, at any weight, cannot be also included for PS4 count. If multiple unrelated probands with the variant have been identified, it is recommended that the case with the highest PP4 points is assigned the appropriate weight for PP4, and the other cases are used for PS4. Variant must meet PM2_Supporting for PP4 to apply at any strength. For PP4 to be applied at strong, full SLC6A8 gene sequencing, including all coding exons and intron/exon boundaries, must have been carried out. If not, consider downgrading. Modification Type: Disease-specific Moderate See points scheme in main document. 3 points required for PP4_Moderate. For PP4, assign points for each type of data present, and then add up the points. PP4 = 1-2 points, PP4_Moderate = 3 points, PP4_Strong = 4 points Two or more data types are recommended to reach moderate and required to reach strong. An individual used to assign PP4, at any weight, cannot be also included for PS4 count. If multiple unrelated probands with the variant have been identified, it is recommended that the case with the highest PP4 points is assigned the appropriate weight for PP4, and the other cases are used for PS4. Variant must meet PM2_Supporting for PP4 to apply at any strength. For PP4 to be applied at strong, full SLC6A8 gene sequencing, including all coding exons and intron/exon boundaries, must have been carried out. If not, consider downgrading. Modification Type: Strength Supporting Elevated urine creatine/creatinine ratio. • 1-2 points required for PP4; at minimum, elevated urine creatine/creatinine level on one occasion. For PP4, assign points for each type of data present, and then add up the points. PP4 = 1-2 points, PP4_Moderate = 3 points, PP4_Strong = 4 points Two or more data types are recommended to reach moderate and required to reach strong. An individual used to assign PP4, at any weight, cannot be also included for PS4 count. If multiple unrelated probands with the variant have been identified, it is recommended that the case with the highest PP4 points is assigned the appropriate weight for PP4, and the other cases are used for PS4. Variant must meet PM2_Supporting for PP4 to apply at any strength. For PP4 to be applied at strong, full SLC6A8 gene sequencing, including all coding exons and intron/exon boundaries, must have been carried out. If not, consider downgrading. Modification Type: Disease-specific Not Applicable
PP5
Original ACMG Summary Reputable source recently reports variant as pathogenic, but the evidence is not available to the laboratory to perform an independent evaluation. Not Applicable This criterion is not for use as recommended by the ClinGen Sequence Variant Interpretation VCEP Review Committee. PubMed : 29543229
BA1 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Allele frequency is above 5% in Exome Sequencing Project, 1000 Genomes or Exome Aggregation Consortium. Stand Alone Allele frequency >0.0020 (0.2%) OR ≥10 hemizygotes in gnomAD Modification Type: Disease-specific Very Strong Strong Moderate Supporting Not Applicable
BS1 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Allele frequency is greater than expected for disorder. Stand Alone Very Strong Strong Allele frequency > 0.0002 (0.02%) OR ≥ 5 hemizygotes in gnomAD Modification Type: Disease-specific Moderate Supporting Not Applicable
BS2 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Observed in a healthy adult individual for a recessive (homozygous), dominant (heterozygous), or X-linked (hemizygous) disorder, with full penetrance expected at an early age. Stand Alone Very Strong Strong Observed in the homozygous state in a healthy adult Modification Type: None Moderate Supporting Not Applicable
BS3 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Well-established in vitro or in vivo functional studies show no damaging effect on protein function or splicing. Stand Alone Very Strong Strong Moderate Supporting Creatine transport assay demonstrating ≥50% normal transport activity using physiological creatine concentrations (≤125μM creatine). RT-PCR evidence demonstrating no observable effect of splicing. Expression assay demonstrating wild type transcript levels Modification Type: Strength,Disease-specific Not Applicable
BS4 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Lack of segregation in affected members of a family. Caveat: The presence of phenocopies for common phenotypes (i.e. cancer, epilepsy) can mimic lack of segregation among affected individuals. Also, families may have more than one pathogenic variant contributing to an autosomal dominant disorder, further confounding an apparent lack of segregation. Stand Alone Very Strong Strong Lack of segregation in affected members of a family. Modification Type: None Moderate Supporting Not Applicable
BP1 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Missense variant in a gene for which primarily truncating variants are known to cause disease. Stand Alone Very Strong Strong Moderate Supporting Not Applicable
BP2 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Observed in trans with a pathogenic variant for a fully penetrant dominant gene/disorder or observed in cis with a pathogenic variant in any inheritance pattern. Stand Alone Very Strong Strong Moderate Supporting Not Applicable
BP3 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary In frame-deletions/insertions in a repetitive region without a known function. Stand Alone Very Strong Strong Moderate Supporting Not Applicable
BP4 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Multiple lines of computational evidence suggest no impact on gene or gene product (conservation, evolutionary, splicing impact, etc) Caveat: As many in silico algorithms use the same or very similar input for their predictions, each algorithm cannot be counted as an independent criterion. BP4 can be used only once in any evaluation of a variant. Stand Alone Very Strong Strong Moderate Supporting REVEL score <0.2 for missense variants In frame deletion or insertion predicted benign by PROVEAN, MutPred indel, and MutationTaster. No predicted impact on splicing by SpliceAI and varSEAK. Modification Type: None Not Applicable
BP5 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary Variant found in a case with an alternate molecular basis for disease. Stand Alone Very Strong Strong Moderate Supporting Variant found in a case with an alternate molecular basis for disease. BP5 applicable as described; the case must have specific features of creatine transporter deficiency, such as low creatine on brain magnetic resonance spectroscopy, or elevated urine creatine in order to apply this criterion. Presence of developmental delay and seizures is not sufficient. Modification Type: None Not Applicable
BP6
Original ACMG Summary Reputable source recently reports variant as benign, but the evidence is not available to the laboratory to perform an independent evaluation. Not Applicable This criterion is not for use as recommended by the ClinGen Sequence Variant Interpretation VCEP Review Committee. PubMed : 29543229
BP7 PVS1 PS1 PS2 PS3 PS4 PM1 PM2 PM3 PM4 PM5 PM6 PP1 PP2 PP3 PP4 PP5 BA1 BS1 BS2 BS3 BS4 BP1 BP2 BP3 BP4 BP5 BP6 BP7 Files References
Original ACMG Summary A synonymous variant for which splicing prediction algorithms predict no impact to the splice consensus sequence nor the creation of a new splice site AND the nucleotide is not highly conserved. Stand Alone Very Strong Strong Moderate Supporting A synonymous (silent) variant for which splicing prediction algorithms predict no impact to the splice consensus sequence nor the creation of a new splice site AND the nucleotide is not highly conserved. Modification Type: None Not Applicable