Long-term speech and language developmental issues among children with Duarte galactosemia.

PURPOSE: : There is limited information on long-term outcomes among children with Duarte galactosemia and controversy about treatment of this potentially benign condition. This study examined developmental disabilities and issues that required special education services within a population-based sample of children with Duarte galactosemia. METHODS: : Children born between 1988 and 2001 who were diagnosed with Duarte galactosemia and resided in the five-county metropolitan Atlanta area at birth and from 3 to 10 years of age were linked to the (1) Metropolitan Atlanta Developmental Disabilities Surveillance Program, an ongoing, population-based surveillance system for selected developmental disabilities and (2) Special Education Database of Metropolitan Atlanta. Special education records were reviewed for children who linked. Clinical genetics records were reviewed to assess laboratory levels at the time of diagnosis and metabolic control during treatment. RESULTS: : Of the 59 eligible children, none were found to have intellectual disability, cerebral palsy, hearing loss, vision impairment, or an autism spectrum disorder. However, five, 8.5% of 3 to 10 years or 15.2% of eligible 8 years, were identified as having received special education services, four of whom were confirmed with a speech or language disorder, or were receiving services for speech or language or both compared with 4.5% and 5.9% of children without Duarte galactosemia, respectively. CONCLUSIONS: : Despite galactose restriction until 1 year, select developmental issues associated with special education, specifically involving speech and language, have been found among some children with Duarte galactosemia.

Untreated PKU Patients without Intellectual Disability: What Do They Teach Us?

Phenylketonuria (PKU) management is aimed at preventing neurocognitive and psychosocial dysfunction by keeping plasma phenylalanine concentrations within the recommended target range. It can be questioned, however, whether universal plasma phenylalanine target levels would result in optimal neurocognitive outcomes for all patients, as similar plasma phenylalanine concentrations do not seem to have the same consequences to the brain for each PKU individual. To better understand the inter-individual differences in brain vulnerability to high plasma phenylalanine concentrations, we aimed to identify untreated and/or late-diagnosed PKU patients with near-normal outcome, despite high plasma phenylalanine concentrations, who are still alive. In total, we identified 16 such cases. While intellectual functioning in these patients was relatively unaffected, they often did present other neurological, psychological, and behavioral problems. Thereby, these "unusual" PKU patients show that the classical symptomatology of untreated or late-treated PKU may have to be rewritten. Moreover, these cases show that a lack of intellectual dysfunction despite high plasma phenylalanine concentrations does not necessarily imply that these high phenylalanine concentrations have not been toxic to the brain. Also, these cases may suggest that different mechanisms are involved in PKU pathophysiology, of which the relative importance seems to differ between patients and possibly also with increasing age. Further research should aim to better distinguish PKU patients with respect to their cerebral effects to high plasma phenylalanine concentrations.

Can untreated PKU patients escape from intellectual disability? A systematic review.

BACKGROUND: Phenylketonuria (PKU) is often considered as the classical example of a genetic disorder in which severe symptoms can nowadays successfully be prevented by early diagnosis and treatment. In contrast, untreated or late-treated PKU is known to result in severe intellectual disability, seizures, and behavioral disturbances. Rarely, however, untreated or late-diagnosed PKU patients with high plasma phenylalanine concentrations have been reported to escape from intellectual disability. The present study aimed to review published cases of such PKU patients. METHODS: To this purpose, we conducted a literature search in PubMed and EMBASE up to 8th of September 2017 to identify cases with 1) PKU diagnosis and start of treatment after 7 years of age; 2) untreated plasma phenylalanine concentrations ≥1200 µmol/l; and 3) IQ ≥80. Literature search, checking reference lists, selection of articles, and extraction of data were performed by two independent researchers. RESULTS: In total, we identified 59 published cases of patients with late-diagnosed PKU and unexpected favorable outcome who met the inclusion criteria. Although all investigated patients had intellectual functioning within the normal range, at least 19 showed other neurological, psychological, and/or behavioral symptoms. CONCLUSIONS: Based on the present findings, the classical symptomatology of untreated or late-treated PKU may need to be rewritten, not only in the sense that intellectual dysfunction is not obligatory, but also in the sense that intellectual functioning does not (re)present the full picture of brain damage due to high plasma phenylalanine concentrations. Further identification of such patients and additional analyses are necessary to better understand these differences between PKU patients.