OBJECTIVES: PKU is a rare, brain threatening, inherited metabolic disorder characterized by inability of the body to utilize the essential amino acid, phenylalanine. When left untreated, PKU patients are at risk of severe neurological complications, including IQ loss, memory loss, concentration problems, mood disorders, and, in some cases, severe mental retardation. Damage is irreversible, so early detection is crucial. In 2017, the National PKU Alliance Foundation and the National Organization for Rare Disorders with support from the US Food and Drug Administration launched a patient registry to understand the natural history of PKU. Here, we describe patient demographics, diagnosis, genetics, treatment, and disease burden in registry patients.

METHODS: The registry has enrolled 862 patients and collected information from 525 respondents through a secure web-based data collection tool.

RESULTS: The majority (95%, 374/392) of PKU registry patients reside in the United States. Patients ranged from 8 days to 65 years (median 10.8, mean 16.9 years), 96% (483/502) were white, and 59% (304/514) were female. Nearly all patients (95%, 370/389) were diagnosed via newborn screening and 21% (62/404) knew their mutational type. Common conditions reported by PKU patients were anxiety (43%, 117/275), depression (26%, 71/273), eczema (25%, 76/306), and dermatological disease (16%, 50/315). 27% (84/309) of patients reported having broken bones in their medical history. Most (82%, 289/351) patients followed a low protein diet, 59% (213/362) regularly used low protein modified foods, 89% (312/350) used medical foods, 11% (35/321) took Tyrosine regularly, and 13% (42/334) took Omega-3 fatty acid supplements. 74% (182/247) of patients reported problems with insurance coverage for low protein food and 58% (151/259) for medical food.

CONCLUSIONS: This PKU patient registry represents a unique longitudinal data source to understand the natural history of PKU and identify challenges in care.