Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2
The NM_002880.4(RAF1):c.1655A>C(p.Asn552Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N552K) has been classified as Uncertain significance.
RAF1 (HGNC:9829): (Raf-1 proto-oncogene, serine/threonine kinase) This gene is the cellular homolog of viral raf gene (v-raf). The encoded protein is a MAP kinase kinase kinase (MAP3K), which functions downstream of the Ras family of membrane associated GTPases to which it binds directly. Once activated, the cellular RAF1 protein can phosphorylate to activate the dual specificity protein kinases MEK1 and MEK2, which in turn phosphorylate to activate the serine/threonine specific protein kinases, ERK1 and ERK2. Activated ERKs are pleiotropic effectors of cell physiology and play an important role in the control of gene expression involved in the cell division cycle, apoptosis, cell differentiation and cell migration. Mutations in this gene are associated with Noonan syndrome 5 and LEOPARD syndrome 2. [provided by RefSeq, Jul 2008]
MKRN2 (HGNC:7113): (makorin ring finger protein 2) This gene encodes a probable E3 ubiquitin ligase containing several zinc finger domains, that is a member of the makorin RING zinc-finger protein family. This gene overlaps the v-raf-1 murine leukemia viral oncogene homolog 1 (RAF1) gene in an antisense orientation and may have a co-regulatory function with RAF1. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Nov 2012]
This sequence change replaces asparagine, which is neutral and polar, with threonine, which is neutral and polar, at codon 552 of the RAF1 protein (p.Asn552Thr). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with RAF1-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt RAF1 protein function. 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. -