Barth syndrome is associated with a cognitive phenotype

Abstract

Objective: Barth syndrome is a rare, X-linked recessive disorder that affects only boys. The cardinal characteristics include growth retardation, cardioskeletal myopathy, chronic or cyclic neutropenia, and 3-methylglutaconic aciduria. A preliminary study of five young boys with Barth syndrome suggested a distinct cognitive phenotype.

Methods: The present study was designed to explore whether additional evidence for a cognitive phenotype emerged from a larger sample. A psychoeducational assessment battery was administered to 15 boys with Barth syndrome. Data from these boys were compared to data from 15 typically developing boys individually matched on age and grade in school to each of the 15 boys with Barth syndrome.

Results: Although boys with Barth syndrome had age-appropriate performance on all measures of reading-related skills, their performance on mathematics and visual spatial tasks was significantly lower than that of boys in the comparison group. Moreover, specific aspects of visual short-term memory also differed from available norms.

Conclusion: Our findings support the validity of the preliminary findings and reflect a higher incidence of cognitive difficulties in boys with Barth syndrome relative to boys in the comparison group. Coupled with the fatigue regularly experienced by boys with Barth syndrome, our findings indicate that educational support should be implemented during the early school-age years for children with Barth syndrome.

Figure 1

Individual test scores for participant 16, and group means (with SD bars) for the Barth syndrome and comparison groups. All scores except Reaction Times (RTs) are converted to a common standard scale (mean = 100, SD = 15). Note that RTs for RAN numbers and letters are imputed because participant #16 could not complete either of these two subtests. The imputed scores used as best estimates of performance were based on the total study sample group mean + 2 SDs. SB-IV, Stanford-Binet, Fourth Edition; WJ-R, Woodcock Johnson-Revised; RAN, Rapid Automatized Naming; TEMA-2, Test of Early Math Ability, Second Edition; VMI, Beery-Buktenica Developmental Test of Visual-Motor Integration; DVTP, Developmental Test of Visual Perception.