The report, authored by Joanna Rokosz-Mierzwa, Katarzyna Reszka, Łucja Walczak and Monika Lejman, was published on 20 October 2026 as volume 53, article number 1763 of the journal.
ARTHS is a genetic condition caused by heterozygous pathogenic or likely pathogenic variants in KAT6A. According to the authors, the main features reported in affected individuals include developmental delay, dysmorphism, low-set posteriorly rotated ears, a prominent nasal bridge, epicanthal folds, hypotonia, poor speech development, feeding difficulties, and cardiovascular anomalies.
The proband in this case was born to healthy parents, and diagnostic evaluation began when he was 18 months old because he reached developmental milestones significantly later than expected. Genetic testing identified a pathogenic, de novo nonsense variant in KAT6A, designated c.3055C>T (p.Arg1019Ter). On the basis of this finding and the boy’s clinical features, the team attributed his presentation to ARTHS.
The authors emphasise that the diagnosis was reached through genomic sequencing even though the boy did not display the full clinical picture classically associated with the syndrome.
A distinctive contribution of the report is its longitudinal character. By providing clinical documentation across several years of the boy’s development, the authors say the case broadens the recognised phenotypic spectrum of ARTHS and adds to understanding of KAT6A-related phenotypic variability and natural history.
As a single-patient case report, the findings describe one child’s experience and cannot by themselves establish how frequently particular features occur across all people with KAT6A variants. Nevertheless, the authors present the case as evidence that genomic sequencing can secure a molecular diagnosis in children with unexplained developmental delay, and that detailed long-term clinical documentation of such patients can refine the recognised boundaries of a rare syndrome’s presentation.
Subject of Research: Phenotypic variability of Arboleda-Tham syndrome in a Polish patient with a pathogenic KAT6A variant
Article Title: Phenotypic variability in Arboleda-Tham syndrome: a report of a polish patient with a pathogenic KAT6A variant
Article References: Rokosz-Mierzwa, J., Reszka, K., Walczak, Ł., & Lejman, M. (2026). Phenotypic variability in Arboleda-Tham syndrome: a report of a polish patient with a pathogenic KAT6A variant. Molecular Biology Reports, 53(1), Article 1763. https://doi.org/10.1007/s11033-026-12943-z
Image Credits: AI Generated
DOI: 10.1007/s11033-026-12943-z
Keywords: Arboleda-Tham syndrome, KAT6A, genetic variant, developmental delay, genomic sequencing, case report, de novo mutation, nonsense variant, phenotypic variability, rare disease, Phenotypic, variability
News Source: Juliet Wilcox. (October 28, 2026). Polish boy’s KAT6A variant expands known spectrum of Arboleda-Tham syndrome. Scienmag.
