Total submissions: 9
Submitter | RCV | SCV | Clinical significance | Condition | Last evaluated | Review status | Method | Comment |
---|---|---|---|---|---|---|---|---|
Undiagnosed Diseases Network, |
RCV000735432 | SCV000746562 | uncertain significance | Noonan syndrome 2 | 2017-05-01 | criteria provided, single submitter | clinical testing | This family has been reported in PMID:29469822. |
Gene |
RCV000681140 | SCV000808598 | pathogenic | not provided | 2022-02-11 | criteria provided, single submitter | clinical testing | Non-canonical splice site variant demonstrated to result in loss-of-function; inclusion of 117bp from an alternate exon lead to a truncated protein, p.(T648fs*36), that was subject to nonsense mediated decay (Johnston et al., 2018; Hanses et al. 2020); This variant is associated with the following publications: (PMID: 29469822, 32623905, 34747535) |
Broad Center for Mendelian Genomics, |
RCV000735432 | SCV001445972 | pathogenic | Noonan syndrome 2 | 2023-05-02 | criteria provided, single submitter | curation | The heterozygous c.1943-256C>T variant in LZTR1 was identified by our study in the compound heterozygous state, along with another likely pathogenic variant, in 2 siblings with Noonan syndrome 2. The variant has been reported in 8 individuals of unknown ethnicity with Noonan syndrome 2 (PMID: 29469822, 32623905) and segregated with disease in 4 affected relatives from 3 families (PMID: 29469822, 32623905). This variant has been identified in 0.019% (3/15796) of African chromosomes by the Genome Aggregation Database (gnomAD, http://gnomad.broadinstitute.org; dbSNP ID: rs761685529). Although the c.1943-256C>T variant has been seen in the general population in a heterozygous state, its frequency is not high enough to rule out a pathogenic role. This variant has also been reported in ClinVar (Variation ID: 522800) as pathogenic by OMIM and GeneDx, and as having unknown significance by the Undiagnosed Diseases Network, NIH. Of the 10 affected individuals, 2 of those were homozygotes, 5 were compound heterozygotes that carried a reported pathogenic/likely pathogenic variants in trans, and 3 were compound heterozygotes that carried a variants of uncertain significance in trans, which increases the likelihood that the c.1943-256C>T variant is pathogenic (VariationID: 522799, 372684; PMID: 29469822, 32623905). In vitro functional studies provide some evidence that the variant may impact protein function (PMID: 29469822, 32623905). However, these types of assays may not accurately represent biological function. Computational prediction tools and conservation analyses do not provide strong support for or against an impact to the protein. In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive Noonan syndrome 2. ACMG/AMP Criteria applied: PM3_strong, PP1_strong, PS3_moderate (Richards 2015). |
Ambry Genetics | RCV002413779 | SCV002719307 | pathogenic | Hereditary cancer-predisposing syndrome; Cardiovascular phenotype | 2021-10-20 | criteria provided, single submitter | clinical testing | The c.1943-256C>T intronic pathogenic mutation results from a C to T substitution 256 nucleotides upstream from coding exon 17 in the LZTR1 gene. This alteration has been reported in multiple individuals with autosomal recessive Noonan syndrome in trans with other mutations or in the homozygous state and was shown to segregate with disease in several families (Johnston JJ et al. Genet Med. 2018 Oct;20(10):1175-1185). RNA studies demonstrated that this alteration results in the retention of a 117-base pair alternate exon that lies within intron 16 (Johnston JJ et al. Genet Med. 2018 Oct;20(10):1175-1185; Hanses U et al. Circulation, 2020 Sep;142:1059-1076; Ambry internal data). Based on the supporting evidence, this variant is pathogenic for an increased risk of LZTR1-related schwannomatosis (SWN) and would be expected to cause autosomal recessive Noonan syndrome when present along with a second pathogenic or likely pathogenic variant on the other allele. |
Women's Health and Genetics/Laboratory Corporation of America, |
RCV000735432 | SCV002766330 | pathogenic | Noonan syndrome 2 | 2022-11-11 | criteria provided, single submitter | clinical testing | Variant summary: LZTR1 c.1943-256C>T is located within intron 16 at a position not widely known to affect splicing. However, several computational tools predict a significant impact on normal splicing: Four predict the variant strengthens a cryptic 5' donor site. At least two publications report experimental evidence that this variant indeed affects mRNA splicing, resulting in the inclusion of the additional 117 bp cryptic exon between exons 16 and 17 (e.g. Johnston_2018, Hanses_2020). The variant allele was found at a frequency of 4.1e-05 in 147296 control chromosomes (gnomAD). c.1943-256C>T has been reported in the literature as a biallelic genotype in multiple individuals affected with Noonan Syndrome 2 from at least five different families in which the variant was found to segregate with the disease in an autosomal recessive pattern of inheritance (e.g. Johnston_2018, Hanses_2020). These data indicate that the variant is very likely to be associated with disease. Four submitters have provided clinical-significance assessments for this variant to ClinVar after 2014. The majority classified the variant as pathogenic (n=3) and one classified it as VUS. Based on the evidence outlined above, the variant was classified as pathogenic. |
Labcorp Genetics |
RCV000681140 | SCV003021760 | pathogenic | not provided | 2024-01-18 | criteria provided, single submitter | clinical testing | This sequence change falls in intron 16 of the LZTR1 gene. It does not directly change the encoded amino acid sequence of the LZTR1 protein. RNA analysis indicates that this variant induces altered splicing and may result in an absent or disrupted protein product. This variant is present in population databases (rs761685529, gnomAD 0.02%). This variant has been observed in individuals with Noonan syndrome (PMID: 29469822, 32623905). ClinVar contains an entry for this variant (Variation ID: 522800). Studies have shown that this variant results in activation of a cryptic splice site and introduces a premature termination codon (PMID: 29469822, 32623905). The resulting mRNA is expected to undergo nonsense-mediated decay. For these reasons, this variant has been classified as Pathogenic. |
Rady Children's Institute for Genomic Medicine, |
RCV003336096 | SCV004046353 | pathogenic | Noonan syndrome | criteria provided, single submitter | clinical testing | This variant has been previously reported as a homozygous and compound heterozygous change in individuals with Noonan syndrome and shown to moderately segregate with disease in two families (PMID: 29469822). Heterozygous carrier parents demonstrated mild or no clinical manifestations (PMID: 29469822). Splicing studies using the RNA from a patient's lymphoblasts showed an abnormal product retaining a 117bp sequence from intron 16 (PMID: 29469822). It is present in the heterozygous state in the gnomAD population database at a frequency of 0.006% (11/178598) and is absent in the homozygous state, and thus is presumed to be rare. Based on the available evidence, the c.1943-256C>T variant is classified as Pathogenic. | |
Baylor Genetics | RCV003465362 | SCV004191286 | pathogenic | Schwannomatosis 2 | 2023-12-21 | criteria provided, single submitter | clinical testing | |
OMIM | RCV000735432 | SCV000863567 | pathogenic | Noonan syndrome 2 | 2018-12-17 | no assertion criteria provided | literature only |