Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2BP4_Strong
The NM_001042432.2(CLN3):c.126-4C>T variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000138 in 1,452,588 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.
CLN3 (HGNC:2074): (CLN3 lysosomal/endosomal transmembrane protein, battenin) This gene encodes a protein that is involved in lysosomal function. Mutations in this, as well as other neuronal ceroid-lipofuscinosis (CLN) genes, cause neurodegenerative diseases commonly known as Batten disease or collectively known as neuronal ceroid lipofuscinoses (NCLs). Many alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Jul 2008]
CLN3 Gene-Disease associations (from GenCC):
inherited retinal dystrophy
Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
neuronal ceroid lipofuscinosis
Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
neuronal ceroid lipofuscinosis 3
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics, Genomics England PanelApp, G2P, Labcorp Genetics (formerly Invitae), Myriad Women’s Health
⚠️ 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:
33292
American (AMR)
AF:
0.00
AC:
0
AN:
43712
Ashkenazi Jewish (ASJ)
AF:
0.00
AC:
0
AN:
25952
East Asian (EAS)
AF:
0.00
AC:
0
AN:
39412
South Asian (SAS)
AF:
0.00
AC:
0
AN:
84862
European-Finnish (FIN)
AF:
0.00
AC:
0
AN:
52910
Middle Eastern (MID)
AF:
0.00
AC:
0
AN:
5760
European-Non Finnish (NFE)
AF:
0.00000181
AC:
2
AN:
1106680
Other (OTH)
AF:
0.00
AC:
0
AN:
60008
⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000081), which strongly suggests a high chance of mosaicism in these individuals.