Identification of newborns with galactosemia based on altered amino acids profile in the metabolic newborn screening

Marcão, Ana; Carvalho, Ivone; Sousa, Carmen; Fonseca, Helena; Rocha, Hugo; Lopes, Lurdes; Neiva, Raquel; Vilarinho, Laura

http://hdl.handle.net/10400.18/5518

Use this identifier to reference this record.

Name:	Description:	Size:	Format:
Identification of newborns with galactosemia.pdf		130.04 KB	Adobe PDF	Download

Send Feedback

Authors

Abstract(s)

Classic galactosemia (CG) is an autosomal recessive disorder caused by deficient activity of galactose-1-phosphate uridyltransferase (GALT). Clinically, this pathology presents in the neonatal period, with acute manifestations following milk intake, and is often fatal during infancy. Galactose restricted diet, the only currently available therapeutic strategy, can prevent or resolve the acute symptoms, but it is ineffective in preventing long-term complications, even in the cases with early identification and treatment. This pathology is frequently included in newborn screening (NBS) programs; nevertheless the risks and benefits of this screening are not sufficiently evaluated and its inclusion in NBS panels is not consensual. In Europe, it is only included in a minority of programs, while it is performed in all states of US. The Portuguese NBS program doesn’t include CG screening; however, several cases have been identified due to increased values of phenylalanine or, since the introduction of mass spectrometry analysis in 2004, due to the combination of increased values of phenylalanine and tyrosine or methionine in the metabolic screening. These three amino acids are markers of four different metabolic diseases, included in the Portuguese NBS panel, namely, phenylketonuria, tyrosinemia, classical homocystinuria and methionine adenosyltransferase I/III deficiency. Their combined increase is suggestive of galactosemia and, as differential diagnosis, in these cases total galactose is determined in the NBS sample. If an increased value of total galactose is found, these results are urgently reported to the metabolic center closer to the parents’ house. Since 2004, from the 1 016 168 newborns included in expanded NBS, eighteen positive cases for CG come to our knowledge, but only eight of this cases presented NBS results suggestive of CG. With the available data it wasn’t possible to establish any correlation between the NBS result and the sampling day or the specific mutations found in each case.