Newborn screening for Fabry disease in Oregon: Approaching the iceberg of A143T and variants of uncertain significance

Digital microfluidic platform for dried blood spot newborn screening of lysosomal storage diseases in Campania region (Italy): Findings from the first year pilot project

BACKGROUND

Newborn screening (NBS) is a simple, non-invasive test that allows for the early identification of genetic diseases within the first days of a newborn's life. The aim of NBS is to detect potentially fatal or disabling conditions in newborns as early as possible, before the onset of disease symptoms. Early diagnosis enables timely treatments and improves the quality of life for affected patients.

RESULTS

A pilot project for dried blood spot (DBS) NBS of lysosomal storage diseases (LSDs), including Mucopolysaccharidosis I (MPSI, IDUA α-L-iduronidase deficiency), Pompe disease (GAA α-glucosidase acid deficiency), Gaucher disease (GBA β-glucosidase deficiency) and Fabry disease (GLA α-galactosidase deficiency), was conducted using the digital microfluidic (DMF) technique. DBS were analyzed in a multiplexed assays for the enzymatic activities of four lysosomal enzymes (IDUA, GAA, GBA, GLA), and subjects identified as deficient in any of these enzymes were referred to the clinical reference center for diagnosis confirmation. From June 6th, 2022, to May 12th, 2023, a total of 7650 newborns were analyzed and 1 subject affected by Pompe disease was identified together with two additional subjects, suspected of Pompe and Fabry disease respectively, for whom continued follow-up is mandatory to determine the phenotype.

CONCLUSIONS

The pilot project for DBS NBS of four LSDs in Campania Region validated the effectiveness of DMF method, established enzymatic activity cut-offs, and identified newborns referred to the clinical center for integrated diagnostics, including genetic analyses. The results suggest that this technique can effectively detect potentially affected newborns, who will require further diagnostic confirmation and clinical follow-up. This diagnostic flow chart provides the opportunity to initiate early treatments and improve LSD patients' life span.

Prospective characterization of early symptom onset and progression in young pediatric patients with variants in the G LA gene across 5 years: Longitudinal data from the Fabry MOPPet Study

Purpose

This prospective, longitudinal study was designed to determine the natural history of Fabry disease (FD) in early pediatric patients across the disease spectrum.

Methods

In this observational study of children under 5 years of age with variants in the GLA gene, prospective phenotypic and urinary biomarker data were collected annually over 5 years.

Results

The study population included 40 participants (35 male, 5 female) with GLA variants including 15 with classic pathogenic variants (CFD), 6 with nonclassic pathogenic variants (NFD), and 19 with a variant of uncertain significance. The most common first symptoms reported were in participants with CFD and included gastrointestinal symptoms (13/15), heat intolerance (13/15), reduced sweating after previously sweating normally (6/15), and neuropathic pain/uncomfortable feet/hands (3/15). Mapping symptom onset and progression reveals a consistent pattern of frequency and severity occurring in the first years of life and beginning at an average age of 23.4 months (range 11-32 months) in males with CFD. Participants with nonclassic pathogenic variants and variant of uncertain significance did not exhibit consistency in symptom onset or progression during the study period.

Conclusion

This study highlights the onset and pattern of progression of the earliest Fabry-related symptoms in children with CFD.

Experience with cascade screening: A comprehensive family pedigree analysis of two index patients with Fabry disease

The wide range of clinical symptoms observed in patients with Fabry disease (FD) often leads to delays in diagnosis and initiation of treatment. Delayed initiation of therapy may result in end-organ damage, such as chronic renal failure, hypertrophic cardiomyopathy, and stroke. Although some tools are available to identify undiagnosed patients, new comprehensive screening methods are needed. In this study, the outcomes of the cascade screening applied to three index cases with FD from 2 familes were investigated. In the pedigree analysis, 280 individuals were included; out of them, 131 individuals underwent genetic testing and cascade screening for FD. During the screening program, a total of 45 individuals were diagnosed, with a diagnostic ratio of 1:15. The average age at diagnosis for all individuals was 30.9 ± 17.7 years, and %25 were pediatric cases (mean age 9.5 ± 5.9 years). Thirty affected relatives were diagnosed from the two index cases in Family 1 and 15 individuals were diagnosed from one index case in Family 2. There were 13 consanguineous marriages observed among 2 pedigres, in two both spouses  were affected, leading to two homozygous affected daughters in one couple. In regions where there is a high prevalence of consanguineous marriages, implementing the cascade screening approach to identify all individuals at risk can be beneficial for patients with FD, specifically women and children.

Current Status of Newborn Bloodspot Screening Worldwide 2024: A Comprehensive Review of Recent Activities (2020-2023)

Newborn bloodspot screening (NBS) began in the early 1960s based on the work of Dr. Robert "Bob" Guthrie in Buffalo, NY, USA. His development of a screening test for phenylketonuria on blood absorbed onto a special filter paper and transported to a remote testing laboratory began it all. Expansion of NBS to large numbers of asymptomatic congenital conditions flourishes in many settings while it has not yet been realized in others. The need for NBS as an efficient and effective public health prevention strategy that contributes to lowered morbidity and mortality wherever it is sustained is well known in the medical field but not necessarily by political policy makers. Acknowledging the value of national NBS reports published in 2007, the authors collaborated to create a worldwide NBS update in 2015. In a continuing attempt to review the progress of NBS globally, and to move towards a more harmonized and equitable screening system, we have updated our 2015 report with information available at the beginning of 2024. Reports on sub-Saharan Africa and the Caribbean, missing in 2015, have been included. Tables popular in the previous report have been updated with an eye towards harmonized comparisons. To emphasize areas needing attention globally, we have used regional tables containing similar listings of conditions screened, numbers of screening laboratories, and time at which specimen collection is recommended. Discussions are limited to bloodspot screening.

Newborn Screening for Fabry Disease: Current Status of Knowledge

Fabry disease is an X-linked progressive lysosomal disorder, due to α-galactosidase A deficiency. Patients with a classic phenotype usually present in childhood as a multisystemic disease. Patients presenting with the later onset subtypes have cardiac, renal and neurological involvements in adulthood. Unfortunately, the diagnosis is often delayed until the organ damage is already irreversibly severe, making specific treatments less efficacious. For this reason, in the last two decades, newborn screening has been implemented to allow early diagnosis and treatment. This became possible with the application of the standard enzymology fluorometric method to dried blood spots. Then, high-throughput multiplexable assays, such as digital microfluidics and tandem mass spectrometry, were developed. Recently DNA-based methods have been applied to newborn screening in some countries. Using these methods, several newborn screening pilot studies and programs have been implemented worldwide. However, several concerns persist, and newborn screening for Fabry disease is still not universally accepted. In particular, enzyme-based methods miss a relevant number of affected females. Moreover, ethical issues are due to the large number of infants with later onset forms or variants of uncertain significance. Long term follow-up of individuals detected by newborn screening will improve our knowledge about the natural history of the disease, the phenotype prediction and the patients' management, allowing a better evaluation of risks and benefits of the newborn screening for Fabry disease.