[Neonatal screening of severe combined immunodeficiencies]

Severe combined immunodeficiency is the first immune deficiency disorder which was included in the newborn screening program in the United States in 2010. In Hungary, newborn screening for severe combined immunodeficiencies is crucial because of the routine BCG vaccination, as in the case of an affected newborn with negative family history, the vaccine may lead to fatal BCG-itis. This paper analyzes the possibilities of introducing newborn screening for severe combined immunodeficiencies and summarizes current experiences and results. Orv Hetil. 2018; 159(23): 948-956.

[Maternal and neonatal vitamin B12 deficiency detected by expanded newborn screening]

INTRODUCTION

Infant vitamin B₁₂ deficiency can manifest as a severe neurodegenerative disorder and is usually caused by maternal deficiency due to vegetarian diet or pernicious anaemia. Its early recognition and treatment can prevent potentially serious and irreversible neurologic damage. Biochemically, vitamin B₁₂ deficiency leads to an accumulation of methylmalonic acid, homocysteine, and propionylcarnitine. Expanded newborn screening using tandem mass spectrometry may identify neonatal and maternal vitamin B₁₂ deficiency by measurement of propionylcarnitine and other metabolites in the dried blood spot sample of newborns.

AIM

To summarize our experiences gained by screening for vitamin B₁₂ deficiency.

METHOD

Clinical and laboratory data of vitamin B₁₂-deficient infants diagnosed in Szeged Screening Centre were retrospectively analysed.

RESULTS

In Hungary, expanded newborn screening was introduced in 2007. Since then approximately 395 000 newborns were screened in our centre and among them, we identified four newborns with vitamin B₁₂ deficiency based on their screening results. In three cases an elevated propionylcarnitine level and in the fourth one a low methionine level were indicative of vitamin B₁₂ deficiency. We also detected an additional vitamin B₁₂-deficient infant with neurological symptoms at 4 months of age, after a normal newborn screening, because of elevated urinary methylmalonic acid concentration. Vitamin B₁₂ deficiency was secondary to maternal autoimmune pernicious anaemia in all the five infants. As a result of the recognized cases the incidence of infant vitamin B₁₂ deficiency in the East-Hungarian region was 1.26/100 000 births, but the real frequency may be higher. Conslusions: Optimizing the cut off values of current screening parameters and measuring of methylmalonic acid and/or homocysteine in the dried blood spot, as a second tier test, can improve recognition rate of vitamin B₁₂ deficiency. Orv Hetil. 2017; 158(48): 1909-1918.

[Diagnostics of inborn errors of metabolism: laboratory approaches]

Inherited errors of metabolism are rare genetic disorders characterized by diverse clinical and biochemical phenotypes. The complexity of signs and symptoms often presents a challenge for both clinicians and laboratory specialists. In many cases, prevention of permanent neurological symptoms or death in patients presenting these disorders is dependent on early diagnosis and introduction of appropriate therapy. For professionals it is indispensable to be familiar with the major clinical signs of inborn errors of metabolism and with the necessary and available laboratory studies to achieve an early diagnosis. The review tries to give a way of approach, diagnostic algorithm of laboratory measurements for the correct diagnosis in inherited errors of metabolism. The combination of biochemical and clinical signs, results of special metabolic investigations represent a portentous challenge in general practice. For the correct diagnosis of an inherited error of metabolism, the teamwork between clinicians and laboratory specialists is indispensable. Orv Hetil. 2017; 158(48): 1903-1907.