Importance of Studying Older Siblings of Patients Identified by Newborn Screening: a Single-Center Experience in Mexico

Isabel Ibarra-González,Cynthia Fernández-Lainez,Sara Guillén-López,Marcela Vela-Amieva,Lizbeth López-Mejía,Leticia Belmont-Martínez,Rosa Itzel Nieto-Carrillo

doi:10.1590/2326-4594-jiems-2021-0001

Abstract

Abstract Introduction: Any abnormal newborn screening (NBS) test should be subjected to appropriate diagnostic tests and should be followed. Once the newborn has been diagnosed and treated, the family should receive comprehensive genetic services. Aim: To present the experience of studying older siblings of patients with inborn errors of metabolism (IEM) identified by NBS in a single-national follow-up reference center. Methods: A retrospective analysis of medical files of the IEM patients detected by NBS was conducted. All those older siblings who tested positive for the same IEM of the patient detected by newborn screening were included. Results: A total of 26 positive siblings from 18 families with seven different IEM were found (phenylketonuria, argininemia, glucose-6-phosphate dehydrogenase deficiency, 3-methylcrotonyl-CoA carboxylase deficiency, dihydropteridine reductase deficiency, tyrosinemia type 3, and medium chain acyl-CoA dehydrogenase deficiency). The age range of the affected siblings was 2 to 19 years old, with a mean age of 8.5 years. Ten older siblings (38.5%) had clinical consequences for the disease, including severe intellectual disability. Conclusions: It is necessary to study older siblings, and family history and genetic counseling of all NBS-detected families should be recommended, especially in countries where expanded NBS programs are beginning.

Highlights

Any abnormal newborn screening (NBS) test should be subjected to appropriate diagnostic tests and should be followed
Almost all the diseases detected by NBS are genetic, and most of them have an autosomal recessive mode of inheritance, which means that both parents are asymptomatic carriers and that in each pregnancy, there is a 25% risk of having an affected child [4]
Any abnormal NBS test should be subjected to appropriate diagnostic tests and must be closely followed, preferably in specialized reference centers [5,6]

Summary

Introduction

Any abnormal newborn screening (NBS) test should be subjected to appropriate diagnostic tests and should be followed. In some high-income countries, follow-up NBS activities are carried out by metabolic teams in which geneticists and genetic counselors are fundamental members, along with other specialists, social workers, and metabolic nurses [1]. Even in those countries, there is variability in the access to genetic services [7]; Received January 12, 2021, and in revised form March 08, 2021.

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