[Diagnosis of a child with Say-Barber-Biesecker-Young-Simpson syndrome due to variant of KAT6B gene].

OBJECTIVE
To analyze the genotype and clinical phenotype of a 3-month-old female infant featuring unresponsiveness.


METHODS
The infant was subjected to genetic testing, and her clinical features were compared with syndromes associated with variants of the candidate gene.


RESULTS
The patient has featured long fingers, long and overlapped toes, musk-like face, blepharophimosis, ptosis, and lacrimal duct anomaly. She was found to harbor a heterozygous de novo variant NM_012330.3: c.3040C>T (p.Gln1014*) in exon 16 of the KAT6B gene. Her clinical phenotype and genotype have both conformed to Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS).


CONCLUSION
The child was diagnosed with SBBYSS syndrome due to the c.3040C>T (p.Gln1014*) variant of the the KAT6B gene. Discovery of the unique features has expanded the phenotypic spectrum of this syndrome.