Nomenclature complex variant in the COQ8B gene

[Evelien Van Hoof]

Dear HGVS team,

 

I was hoping to ask for you advice on a complex rearrangement we have identified. We would like the correct nomenclature to report this variant.

 

We identified a homozygous deletion of exons 5-6 of the COQ8B gene (NM_024876.4) using whole exome sequencing. We performed a PCR-based test to confirm the presence of this deletion and encountered a more complex variant.

We see a deletion of the following region: chr19-40711423-40705323 with an insertion of the complement of chr19:40709896-40709804 (which is a part of intron 5).

 

The figure shows a schematic overview:

 

What is the correct nomenclature to use and how can be best describe this in the clinical report?

 

Thanks,

Kind regards,

 

Evelien

 

Evelien Van Hoof
pijler Inwendige ziekten
Centrum Menselijke Erfelijkheid

 

evelien...@uzleuven.be

tel secr. + 32 16 34 59 03
fax secr. + 32 16 34 60 60 

 

UZ Leuven | campus Gasthuisberg | Herestraat 49 | B - 3000 Leuven | Belgie

www.uzleuven.be 

 

KU Leuven 

www.kuleuven.be

 

[Johan den Dunnen]

Dear Evelien,

based on your description, following HGVS nomenclature, I get to NC_000019.10:g.40705323_40711423delins40709804_40709896inv to describe the variant.

Best regards,

Johan den Dunnen
HUGO HGVS Variant Nomenclature Committee (HVNC)

Op woensdag 11 februari 2026 om 17:03:26 UTC+1 schreef Evelien Van Hoof:

[Mihai Lefter]

Dear Johan,

I was wondering whether NC_000019.10:g.[40705326_40709803del;40709804_40709893inv;40709894_40711423del] might better reflect the structure depicted in the data and accompanying image provided in the original question.

Best regards.

Mihai

[Johan den Dunnen]

Dear Mihai,

when there is a large deletion in which part of the deleted region is inserted in an inverted position, there are two options to describe the variant.

      1.  NC_000019.10:g.A_DdelinsB_Cinv or

      2.  NC_000019.10:g.[A_B-1del;B_Cinv;C+1_Ddel]

However, since the delins description (#1) is shorter, this is the description suggested. However, as far as I know, there is currently no recommendation which would make the second description not HGVS compliant.

Best regards,

Johan den Dunnen
HUGO HGVS Variant Nomenclature Committee (HVNC)

Op maandag 2 maart 2026 om 15:20:48 UTC+1 schreef mihai....@gmail.com: