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Case Reports
. 2025 Jul 2;25(1):997.
doi: 10.1186/s12903-025-06197-7.

Syndromic gingival fibromatosis associated with pathogenic variation in the voltage-gated potassium channel gene KCNH1: a case report and proposed treatment protocol

Nhat Minh Do #  1   2   3 , Pierre Klienkoff #  4   5 , Anne de Saint Martin  6   7 , Alexandra Jimenez-Armijo  8   9   7 , Elise Schaefer  10 , Gaétan Caravello  9   11 , Lucas Geyer  12 , Sarah Baer  6   7 , Laurent Marcoux  13 , François Clauss  8   9   14   15 , Agnès Bloch-Zupan  8   9   14   7   16
Affiliations
Case Reports

Syndromic gingival fibromatosis associated with pathogenic variation in the voltage-gated potassium channel gene KCNH1: a case report and proposed treatment protocol

Nhat Minh Do et al. BMC Oral Health. .

Abstract

Background: The KCNH1 gene (OMIM #603,305) encodes a voltage-gated potassium channel primarily found in the central nervous system. Recent discoveries have linked pathogenic variations in this gene to Temple-Baraitser syndrome (TMBTS, OMIM #611,816) and Zimmermann-Laband syndrome (ZLS, OMIM #135,500). A common manifestation of these syndromes is gingival fibromatosis, which may partially or completely cover tooth crowns, leading in some cases to functional and aesthetic problems, as well as delayed tooth eruption.

Case presentation: A four-year-old boy and his parents first consulted for delayed primary molars eruption. Shortly after birth, he was diagnosed with a developmental encephalopathy caused by a de novo pathogenic variant in KCNH1.

Treatment: The first step of oral treatment consisted of myofunctional and speech/language therapy to stimulate biting and chewing. It also helped with the rehabilitation of proper tongue function. This was followed by a gingivoplasty to expose the submerged teeth. We propose a clinical approach to optimize disease management. This aims to minimize complications associated with this rare disorder.

Conclusion: This case illustrates the need for appropriate and early gingivoplasty to prevent teeth impaction and restore dental function. Additionally, it explores potential complications and provides grounds for a comprehensive protocol for managing gingival fibromatosis for patients with KCNH1 variant.

Keywords: Gingival fibromatosis; Gingival hyperplasia; Gingivoplasty; KCNH1 developmental and epileptic encephalopathy; Temple-Baraitser Syndrome; Zimmermann-Laband Syndrome.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Informed consent about clinical management was obtained from the parents in this case. Consent for publication: Written informed consent was obtained from the parents for the publication of any potentially identifiable images or data included in this article. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Intra-oral photos of the maxilla and mandible and intra oral radiographs
Fig. 2
Fig. 2
Gene panel used for epilepsy and brain development anomaly (333 genes)
Fig. 3
Fig. 3
Examples of chewing toys
Fig. 4
Fig. 4
The patient with his chew toy
Fig. 5
Fig. 5
Incision line for gingivectomy using an electric scalpel
Fig. 6
Fig. 6
Surgical luxation in order to check for ankylosis and stimulate re-eruption of the impacted tooth
Fig. 7
Fig. 7
Incision line of one of the two gingival samples sent for pathological analysis (on the left) and tissue sample for histological analysis (on the right)
Fig. 8
Fig. 8
Final postoperative appearance of gingivectomies performed in the 4 temporary molar sectors (maxilla on the left, mandible on the right)
Fig. 9
Fig. 9
Hematoxylin and eosin staining of gum sector 2 (A) and sector 4 (B) showing hyperparakeratinized hyperplastic squamous epithelium with dense fibrocollagenous tissue and mild inflammatory infiltrate. Original magnification 10x
Fig. 10
Fig. 10
Clinical appearance of the gingiva 10 days after surgery
Fig. 11
Fig. 11
Healing aspect at 12 months post-operatively. A Frontal occlusion, B profile. Close-up view of molars, C sector 5, D sector 6
Fig. 12
Fig. 12
proposed protocol for the management of gingival fibromatosis in patients diagnosed with KCNH1 mutations
See this image and copyright information in PMC

References

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    1. Gripp KW, et al. Syndromic disorders caused by gain-of-function variants in KCNH1, KCNK4, and KCNN3—a subgroup of K+ channelopathies. Eur J Hum Genet. 2021;29(9):1384–95. 10.1038/s41431-021-00818-9. - PMC - PubMed
    1. Simons C, et al. Mutations in the voltage-gated potassium channel gene KCNH1 cause Temple-Baraitser syndrome and epilepsy. Nat Genet. 2015;47(1):73–7. 10.1038/ng.3153. - PubMed
    1. Kortüm F, et al. Mutations in KCNH1 and ATP6V1B2 cause Zimmermann-Laband syndrome. Nat Genet. 2015;47(6):661–7. 10.1038/ng.3282. - PubMed
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