Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PVS1
The NM_020320.5(RARS2):c.1055delA(p.Lys352SerfsTer10) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,611,730 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Variant results in nonsense mediated mRNA decay.
RARS2 (HGNC:21406): (arginyl-tRNA synthetase 2, mitochondrial) This nuclear gene encodes a protein that localizes to the mitochondria, where it catalyzes the transfer of L-arginine to its cognate tRNA, an important step in translation of mitochondrially-encoded proteins. Defects in this gene are a cause of pontocerebellar hypoplasia type 6 (PCH6). Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2016]
RARS2 Gene-Disease associations (from GenCC):
mitochondrial disease
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
pontocerebellar hypoplasia type 6
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics, PanelApp Australia
complex neurodevelopmental disorder
Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.
African (AFR)
AF:
0.00
AC:
0
AN:
33438
American (AMR)
AF:
0.00
AC:
0
AN:
44714
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
26120
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39664
South Asian (SAS)
AF:
0.00
AC:
0
AN:
86208
European-Finnish (FIN)
AF:
0.0000377
AC:
2
AN:
53054
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5766
European-Non Finnish (NFE)
AF:
0.00000270
AC:
3
AN:
1110416
Other (OTH)
AF:
0.00
AC:
0
AN:
60334
⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000031), which strongly suggests a high chance of mosaicism in these individuals.