Submissions for variant NM_024753.5(TTC21B):c.795+3A>G

gnomAD frequency: 0.00008  dbSNP: rs753275145

Total submissions: 5

Submitter	RCV	SCV	Clinical significance	Condition	Last evaluated	Review status	Method	Comment
Illumina Laboratory Services, Illumina	RCV000360819	SCV000417669	uncertain significance	Asphyxiating thoracic dystrophy 4	2018-01-13	criteria provided, single submitter	clinical testing	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.
Illumina Laboratory Services, Illumina	RCV000270836	SCV000417670	uncertain significance	Nephronophthisis 12	2018-01-13	criteria provided, single submitter	clinical testing	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease.
Labcorp Genetics (formerly Invitae), Labcorp	RCV001326971	SCV001518026	uncertain significance	Jeune thoracic dystrophy; Nephronophthisis	2022-10-04	criteria provided, single submitter	clinical testing	This sequence change falls in intron 7 of the TTC21B gene. It does not directly change the encoded amino acid sequence of the TTC21B protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (rs753275145, gnomAD 0.008%). This variant has not been reported in the literature in individuals affected with TTC21B-related conditions. ClinVar contains an entry for this variant (Variation ID: 331837). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant is not likely to affect RNA splicing. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.
Fulgent Genetics, Fulgent Genetics	RCV002504118	SCV002815124	uncertain significance	Asphyxiating thoracic dystrophy 4; Nephronophthisis 12	2022-05-23	criteria provided, single submitter	clinical testing
PreventionGenetics, part of Exact Sciences	RCV004537841	SCV004742139	likely benign	TTC21B-related disorder	2024-07-25	no assertion criteria provided	clinical testing	This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications).