Newborn screening (NBS) is an important public health program that aims to identify pre-symptomatic healthy babies that will develop significant disease if left undiagnosed and untreated. The number of conditions being screened globally is expanding rapidly in parallel with advances in technology, diagnosis, and treatment availability for these conditions. In Hong Kong, NBS for inborn errors of metabolism (NBSIEM) began as a pilot program in October 2015 and was implemented to all birthing hospitals within the public healthcare system in phases, with completion in October 2020. The number of conditions screened for increased from 21 to 24 in April 2016 and then to 26 in October 2019. The overall recruitment rate of the NBS program was 99.5%. In the period between October 2015 and December 2022, 125,688 newborns were screened and 295 were referred back for abnormal results. The recall rate was reduced from 0.26% to 0.12% after the implementation of second-tier testing. An inherited metabolic disorder (IMD) was eventually confirmed in 47 infants, making the prevalence of IMD in Hong Kong 1 in 2674. At the time of the NBS result, 78.7% of the newborns with IMD were asymptomatic. There were two deaths reported: one newborn with methylmalonic acidemia cobalamin B type (MMACblB) died after the initial crisis and another case of carnitine palmitoyltransferase II deficiency (CPTII) died at 18 months of age after metabolic decompensation. The most common IMD noted were disorders of fatty acid oxidation metabolism (40%, 19 cases), closely followed by disorders of amino acid metabolism (38%, 18 cases), with carnitine uptake defect (19.1%, 9 cases) and citrullinemia type II (17%, 8 cases) being the two most common IMD picked up by the NBSIEM in Hong Kong. Out of the all the IMDs identified, 19.1% belonged to diverse ethnic groups. False negative cases were reported for citrullinemia type II and congenital adrenal hyperplasia during this period.

Mitochondrial disorders are multiorgan disorders resulting in significant morbidity and mortality. We aimed to characterize death-associated factors in an international cohort of deceased individuals with mitochondrial disorders. This cross-sectional multicenter observational study used data provided by 26 mitochondrial disease centers from 8 countries from January 2022 to March 2023. Individuals with genetically confirmed mitochondrial disorders were included, along with patients with clinically or genetically diagnosed Leigh syndrome. Collected data included demographic and genetic diagnosis variables, clinical phenotype, involvement of organs and systems, conditions leading to death, and supportive care. We defined pediatric and adult groups based on age at death before or after 18 years, respectively. We used Kruskal-Wallis with post hoc Dunn test with Bonferroni correction and Fisher exact test for comparisons, Spearman rank test for correlations, and multiple linear regression for multivariable analysis. Data from 330 deceased individuals with mitochondrial disorders (191 [57.9%] pediatric) were analyzed. The shortest survival times were observed in hepatocerebral syndrome (median 0.3, interquartile range [IQR] 0.2-0.6 years) and mitochondrial cardiomyopathy (median 0.3, IQR 0.2-5.2 years) and the longest in chronic progressive external ophthalmoplegia plus (median 26.5, IQR 22.8-40.2 years) and sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (median 21.0, IQR 13.8-28.5 years). Respiratory failure and pulmonary infections were the most common conditions associated with death (52/330, 15.7% and 46/330, 13.9%, respectively). Noninvasive ventilation was required more often in children (57/191, 29.8%) than adults (12/139, 8.6%, p < 0.001), as was nasogastric or gastric tube (131/191, 68.6% in children and 39/139, 28.1% in adults, p < 0.001). On multivariate analysis, individuals with movement disorders and nuclear gene involvement had increased odds of any respiratory support use (OR 2.42 (95% CI 1.17-5.22) and OR 2.39 (95% CI 1.16-5.07), respectively). This international collaboration highlights the importance of respiratory care and infection management and provides a reference for prognostication across different mitochondrial disorders.

DNAJC12 deficiency is a recently described inherited metabolic disorder resulting in hyperphenylalaninemia and neurotransmitter deficiency. The effect of treatment on the prevention of neurological manifestations in this newly reported and heterogenous disorder is not fully understood, and the optimal treatment strategy remains to be elucidated. The global or regional incidence of the disease is yet to be estimated. Here, we report the first individual diagnosed with DNAJC12 deficiency in Hong Kong; the condition was picked up by newborn screening due to hyperphenylalaninemia after ruling out phenylalanine hydroxylase deficiency and other tetrahydrobiopterin related disorders. Compound heterozygous variants in the DNAJC12 gene were identified, which included a novel missense change and a nonsense pathogenic variant. Treatment with neurotransmitter precursors (tetrahydrobiopterin, levodopa, and oxitriptan) was initiated at four months of age, and dietary protein restriction was started at four years and six months of age. He remains asymptomatic at four and a half years of age, apart from having mildly impaired socio-communication and language development. In this report, we discuss the current diagnostic approach to hyperphenylalaninemia in newborn screening and the uncertainties that exist in the clinical outcome from earlier detection, treatment, and monitoring of DNAJC12-deficiency patients.

Pyridoxamine 5-phosphate oxidase (PNPO) deficiency is an autosomal recessive inborn error of metabolism that typically manifests as seizures resistant to conventional anticonvulsants, often presenting in the neonatal period to early infancy. One of the main treatments, pyridoxal 5-phosphate (PLP), carry a risk of liver toxicity. Concerns about liver toxicity have emerged not only with high doses of PLP but also with lower doses, prompting further investigation into the relationship between PLP treatment and liver complications in patients with PNPO deficiency. This report presents the first case report of hepatocellular carcinoma (HCC) in a patient with PNPO deficiency receiving PLP Pyridoxamine 5-phosphate oxidase (PNPO), identified before reaching teenager. This case underscores the importance of regular liver function monitoring for patients on long-term PLP therapy, suggesting a potential association between PLP treatment and the development of HCC, which has significant implications for clinical management strategies.

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder and is associated with serious clinical consequences. While newborn screening (NBS) could facilitate early identification and timely intervention, its implementation for X-ALD remains controversial due to ethical concerns arising from its X-linked recessive inheritance pattern, particularly regarding female newborns. This study aims to explore the perspectives of healthcare professionals and the general public on NBS for X-ALD in Hong Kong. An online survey with 20 quantitative questions on ethical considerations was conducted from May to August 2024. Among a total of 259 responses, most respondents (99.2%) supported NBS for their male newborns, primarily because it facilitates early diagnosis and effective management. The majority of the respondents were in favor of offering NBS to female newborns, citing potential benefits for the management of adult-onset disease, enhanced family planning and support, and opportunities for extended family screening. However, some respondents expressed concerns regarding (1) psychological stress and anxiety from uncertain disease onset and frequent monitoring; (2) potential genetic discrimination and adverse impact on insurance premiums/coverage; (3) affordability and accessibility of expensive treatments, such as gene therapy; and (4) ethical issues regarding children’s “right to an open future”, particularly for late-onset female X-ALD. To address these concerns while respecting family autonomy, we propose an opt-in system with clear, balanced information for parents, combined with a three-tier screening algorithm. In summary, while inclusion of X-ALD in Hong Kong’s NBS program receives strong community support, targeted measures are needed to mitigate the identified ethical and practical barriers.