Differential Phonological Awareness Skills in Children with Classic Galactosemia: A Descriptive Study of Four Cases

Abstract

Educational achievement, which for individuals with the metabolic disorder classic galactosemia (GAL) is significantly lower than in the wider population, correlates with self-reported quality of life. Phonological awareness skills underpin the development of literacy, and although literacy is a key contributor to successful academic outcomes, no study to date has investigated phonological awareness skills in children with GAL. This study investigated phonological awareness (PA) in four school-aged children with the disorder, two of whom were siblings. Age range for the children was 7 years 7 months to 9 years 2 months. Each child was assessed with the Phonological Awareness criterionreferenced subtest from the Clinical Evaluation of Language Fundamentals-Fourth Edition. Included in the data for analysis was each child's performance measures obtained from their most recent assessment of cognitive and lexical development. A number of descriptive analyses were undertaken on the data. One child, who met her age criterion for PA, had cognitive and lexical development skills in the average range. The remaining three children failed to meet their age criteria. Although these three children presented with clinically similar cognitive and lexical development skills, disparate PA skills were identified. The PA skills of one of the sibling pair were notably more advanced than his older sibling. The limitations of relying on behavioural test results in children with GAL to predict those most at risk of reduced skill development are discussed in terms future research directions.

Classical galactosemia: neuropsychological and psychosocial functioning beyond intellectual abilities

“…These abilities are referred to as cognitive functioning and encompass domains such as information processing speed, attention, memory, visuospatial functioning and executive functioning. Previous studies reporting on cognitive functioning in CG patients demonstrated below average to low functioning on several cognitive domains [5][6][7][8][9]. However, the outcomes on the cognitive domains differed between studies and results must be interpreted with care because studies mostly addressed only one cognitive domain, used one single test per cognitive domain and/or included small cohorts.…”

Affected functional networks associated with sentence production in classic galactosemia

“…In addition, patients with galactosemia have impairments in language planning (Potter et al, 2013). Vocabulary, grammar and word retrieval problems have been described (Schweitzer et al, 1993;Waggoner et al, 1990;Waisbren et al, 1983), as well as cases with clinically significant delays on pre-linguistic skills (at age 13 month) (Lewis et al, 2013), and failures to meet age-appropriate phonological awareness (aged 7-9) (Lewis et al, 2012). The majority of patients with galactosemia and history of speech sound disorders also have language disorders, which cannot be explained by lower cognitive abilities (Potter et al, 2008).…”

Classic Galactosemia Neurological Complications: An Overview

“…An over restricted galactose diet impairs myelin synthesis secondary to a deficit of galactolipids (galactocerebrosides) and glycoproteins, that is hypoglycosilated because of increased production of nongalactosylated or mono-galactosylated proteins [4,9,[11][12][13]. It has been observed In Vivo that the increased levels of galactose 1-phosphate inhibit glucose pyrophosphorylase reducing UDPglucose/galactose and responsible for impaired glycosylation of proteins and lipids, such problems are different between individual, because the activation of secondary pathways to metabolize galactose can be epigenetic regulated and depend on the individual's genetic characteristics [9,12].…”

“…The treatment goal to maintain galactose 1-phosphate levels below 5 mg/dl with food containing with galactose content of less than 25 mg/100 gr is the backbone of the over restricted diet but is responsible for the impaired glycosylation of proteins leading to decreased white matter synthesis and the posterior neurological symptoms; and increased levels of galactose 1-phosphate are prone to induce oxidative stress and caused neurotoxicity [2][3][4][11][12][13][17][18][19].…”

“…Classic galactosemia patients have impaired language secondary to decreased conceptualization at the early phase of syntactic processing, less efficient syntactic planning, increase time and word usage to express themselves, causing decreased language comprehension, interpretation and manipulation what they are taught; a posterior delay on attaining the literacy skills necessary to achieve a proper academic outcome, and a cause for the observed cognitive impairment [4,5].…”