ABSTRACT: Arboleda-Tham syndrome (OMIM#616268) is a newly named neurodevelopmental disorder, which is an autosomal dominant hereditary disease characterized by genetic variants. The clinical manifestations include global developmental delay, primary microcephaly, and craniofacial dysmorphism, as well as more varied features such as feeding difficulties, cardiac defects, and ocular anomalies. Currently, due to restricted knowledge of Arboleda-Tham syndrome and less specific pathological manifestations, it is difficult to diagnose at the early stages of the disease. Here, we present a case with obvious growth retardation and intellectual disability, accompanied by other manifestations including dysmorphic features of the ears, facial dysmorphism, right cryptorchidism, and inguinal hernia. Routine laboratory tests including blood-urine tandem mass spectrometry, urine gas chromatographic mass spectrometry, karyotype, echocardiography, automatic auditory brainstem responses, serum levels of calcium, phosphorus, vitamin D, creatine kinase (CK), and CK isoenzyme (CK-MB), and brain magnetic resonance imaging showed negative results. A de novo heterozygous variant in KAT6A, c.57delA (p.Val20*), was detected by trio-based whole exome sequencing and subsequent validation by Sanger sequencing in the patient, which was absent in both the parents. The patient received rehabilitation and nutritional intervention. The testis reduction and orchiopexy was scheduled when he was 1 year old. Our report extends the phenotype-genotype map of Arboleda-Tham syndrome, and also expands the mutant spectrum of the KAT6A gene. Moreover, this case emphasizes the timely conduction of whole exome sequencing for the early diagnosis of Arboleda-Tham syndrome, and spares patients from meaningless examinations and ineffective treatments.
