Rubinstein-Taybi Syndrome (RSTS) is a rare multiple congenital autosomal dominant disorder, with an incidence of roughly 1/125,000 live births (Milani et al., 2015). RSTS is characterized by several typical somatic characteristics and developmental disabilities. Common neurological findings in patients with RSTS include mild or moderate intellectual impairment and delays in gross motor development (Taupiac et al., 2021; Hamilton et al., 2016). Additional characteristics observed among individuals with RSTS include hyperactivity, abnormalities in expressive language, inattention, motor difficulties, noise intolerance, maladaptive behaviors, and fewer modes of communication (Waite et al., 2015). Due to the condition’s rarity, very few studies have investigated the cognitive profiles of RSTS patients with clinical features of EP300 (Type 2; Morel et al., 2018) in effected youth. This case study represents the first reported comprehensive neuropsychological description to our knowledge of an individual with this condition.

Participant: The participant is an 8-year, 4-month-old young girl referred for neuropsychological evaluation. LX was diagnosed with failure to thrive due to her small size, although she met all developmental milestones on time. LX was diagnosed with RSTS, Type 2 through genetic testing and blood work following concerns about small stature, microcephaly discovered on an MRI, and feeding difficulties. A 4kb deletion of 22q13.2 which contains exon 2 of EP300 was identified. Method: Medical and school records review, a clinical interview with LX and her family, neuropsychological assessment, and parent-and teacher-report questionnaires were used to assess functioning. Raw scores were standardized for comparison against age- and (where appropriate) gender-matched peers.

In addition to her medical diagnoses of RSTS, Type 2, and her prior diagnosis of ADHD - Combined Subtype, LX also met diagnostic criteria for Specific Learning Disability with Impairment in Reading and a Mixed Receptive-Expressive Language Disorder. LX also met criteria for Encephalopathy as characterized by weakness in visual perception, visuospatial judgment and reasoning, and working memory. LX demonstrated adaptive functioning weaknesses in domains such as self-direction, and self-care, while communication skills were reported to be average. Overall, LX’s current levels of general cognitive ability and adaptive functioning were consistent with Borderline Intellectual Functioning; however, the diagnosis was deferred at present. Parents and teachers reported difficulties with peer relationships, hyperactivity, and aggression, consistent with known features of this condition. Strengths were noted in verbal and nonverbal reasoning, spelling, math calculation, verbal and visual memory, and improvement in attention with medication, which all fell within the broadly average range of functioning.

LX’s presentation and pattern of neuropsychological findings are consistent with the current conceptualization of development in RSTS, Type 2, but reflect a more nuanced clinical picture. In particular, although general cognitive ability was borderline overall, deficits were largely circumscribed to spatial reasoning, with broadly average verbal and nonverbal reasoning abilities. This case highlights the importance of comprehensive neuropsychological testing of patients with RSTS. Reporting of general cognitive ability scores alone may obscure underlying patterns of relative strengths and weaknesses that have important ramifications for both targeted interventions and for a more positive prognosis related to functioning in academic, home, and community environments.