# Qatar’s National Expanded Metabolic Newborn Screening Program: Incidence and Outcomes

## TL;DR

This study reports the incidence of inherited metabolic disorders in newborns in Qatar and highlights the effectiveness of genetic testing in diagnosing these conditions.

## Contribution

The study provides novel incidence data for inherited metabolic disorders in Qatar and evaluates the diagnostic yield of genetic testing methods.

## Key findings

- The incidence of inherited metabolic disorders in Qatar is 1:1105, with classical homocystinuria being the most common.
- Aminoacidopathies were the most prevalent category of disorders detected through newborn screening.
- Genetic testing confirmed 90% of cases, with high confirmation rates for targeted and single gene testing.

## Abstract

Background: Newborn screening is an essential public health strategy that aims to detect a range of conditions, including inborn errors of metabolism, in neonates shortly after birth. The timely identification is crucial due to the asymptomatic nature of many conditions at birth, but which can lead to significant health complications if left untreated. Through this study, we aimed to investigate the incidence of IEMs screened by the Qatar National Newborn Screening Program. Methods: We retrospectively analyzed a total of 351,223 newborns screened from 2010 to 2023. The incidence for the studied IEMs was calculated and correlated with demographics, consanguinity, and family history. In addition, the diagnostic yield of different tests utilized was assessed. Results: Our study revealed a total of 318 positive cases with IEMs, and a significantly high incidence of 1:1105 for IEMs in Qatar. Classical Homocystinuria was the most frequently detected condition, with a cumulative incidence of 1:6754 live births, linked to the founder variant p. Arg336Cys in the CBS gene. Aminoacidopathies were the most prevalent category, followed by fatty acid oxidation disorders, organic acidurias, biotinidase deficiency, and urea cycle disorders. Genetic testing showed a high diagnostic yield of 90%. Of the 60 cases that underwent targeted variant testing, 98% were confirmed, while 90% of the 59 cases tested by single gene testing were confirmed. Conclusions: Our study provides the incidence rates of IEMs in Qatar and novel insights that could facilitate setting up/developing IEM incidence-reducing strategies and improving outcomes for affected newborns and their families.