Question about DMPK mosaicism

[Kristina Aleknavičienė]

Good morning, 

I hope this message finds you well. I would like to confirm the correct HGVS nomenclature for describing the following DMPK expansion mosaicism detected in our analysis.

Based on the results, we identified:

One normal-sized allele with 11 (±1) repeats
Mosaicism with 55 (±2) repeats and 71 (±2) repeats

Would the following notation be correct according to HGVS guidelines?

NM_004409.5:c.*224CTG[11]/[55]/[71] (±2)

If this notation is incorrect, could you please advise on the appropriate way to represent these findings?

Thank you for your time and expertise.

Best regards,

---

Kristina Aleknavičienė
Medicinos genetikė, kokybės vadybininkė

 

Lietuvos sveikatos mokslų universiteto ligoninė 

Kauno klinikos
Mob. tel. +37060529612
El. p. kristina.ale...@kaunoklinikos.lt
www.kaunoklinikos.lt

[Johan den Dunnen]

Dear Kristina,

following current recommendations, the correct description is NM_004409.5:c.*224_*283CTG[11];[55/71].

When you want to include the (±2) uncertainty about the allele length, the description is NM_004409.5:c.*224_*283CTG[(9_13)];[(53_57)/(69_73)].

Note it is recommended to describe the entire length of the repeated segment (c.*224_*283). Note also the ";" character is used to discriminate between the two alleles ([ ]:[ ]).

Best regards,

Johan den Dunnen
HUGO HGVS Variant Nomenclature Committee (HVNC)

Op zaterdag 1 maart 2025 om 12:06:18 UTC+1 schreef Kristina Aleknavičienė: