A Say‐Barber‐Biesecker‐Young‐Simpson variant of Ohdo syndrome with a KAT6B 10‐base pair palindromic duplication: A recurrent mutation causing a severe phenotype mixed with genitopatellar syndrome

Abstract

The Say-Barber-Biesecker-Young-Simpson variant of Ohdo syndrome (SBBYSS) (MIM# 603736) and genitopatellar syndrome (GPS) (MIM#606170) are allelic diseases caused by KAT6B mutation. Genotype-phenotype correlation is assumed, but a few patients manifest overlapping features of both syndromes. Here we report the case of a boy with SBBYSS. He had a KAT6B mutation previously reported in typical SBBYSS, but he also manifested severe developmental delay, as well as genital features and laryngomalacia requiring tracheostomy that conformed to GPS.

Lin‐Gettig syndrome: Craniosynostosis expands the spectrum of the KAT6B related disorders

“…Affected fetuses may demonstrate joint contractures and/or talipes, agenesis of the corpus callosum, or renal abnormalities on prenatal ultrasound. Both patients in this report also presented with polyhydramnios, which has been described previously (Day et al, ; Lundsgaard et al, ; Niida et al, ). Polyhydramnios in KAT6B related disorders is likely multifactorial, due to a combination of abnormal fetal swallowing, micrognathia, hypotonia, and/or bowel malformations.…”

“…Affected fetuses may demonstrate joint contractures and/or talipes, agenesis of the corpus callosum, or renal abnormalities on prenatal ultrasound. Both patients in this report also presented with polyhydramnios, which has been described previously (Day et al, 2008;Lundsgaard et al, 2017;Niida et al, 2017).…”

Novel variants in KAT6B spectrum of disorders expand our knowledge of clinical manifestations and molecular mechanisms

“…Five other individuals (K6B_6, K6B_9, K6B_12, K6B_15, and K6B_20) had variants that were previously reported in the literature and their classifications based upon the (Gannon et al, 2015;Zhang et al, 2020) criteria were concordant with those reports (Bashir et al, 2017;Clayton-Smith et al, 2011;Gannon et al, 2015;Zhang et al, 2020;Zhu et al, 2020). These five individuals had clinical features similar to the individuals reported in the literature with the exception of K6B_20, who lacked every feature appraised in three other individuals with the same variant (Clayton-Smith et al, 2011;Gannon et al, 2015;Niida et al, 2017;Simpson et al, 2012;Szakszon et al, 2013;Zhang et al, 2020).…”

A neonate with Say–Barber–Biesecker–Young–Simpson syndrome with a novel pathogenic mutation in KAT6B gene: A case report

“…But he also had a corpus callosum agenesis, a typical feature of GPS. Another reported a boy that had a KAT6B mutation previously reported in typical SBBYSS, but he also manifested severe developmental delay, as well as genital features and laryngomalacia requiring tracheostomy that confirmed to GPS [14]. Our patient had three major features like distinctive face, long thumbs/great toes, and bleopharophimosis without structural brain defects or respiratory problems suggesting the SBBYSS.…”