Galactosemia is a rare autosomal recessive disorder caused by the deficiency of galactose-1-phosphate uridyltransferase (GALT) enzyme activity. Classic galactosemia (G/G) is due to severe GALT deficiency in the presence of a GALT gene mutation, whereas Duarte variant (D/D) has 50% of normal GALT activity and benign clinical course. The D2 allele of Duarte variant is linked to a promoter deletion 5' to the translation start site (-119 to -116 delGTCA) in addition to N314D. So, Duarte variant/classical galactosemia (D/G) compound heterozygotes have relatively mild clinical manifestation than classical galactosemia and can be differentiated from classical galactosemia or Duarte variant by mutational analysis. We report a case of D/G galactosemia compound heterozygote proven by the reduction of GALT enzyme activity in erythrocytes and mutation analysis of GALT gene, which revealed N314D polymorphism and -119 to -116 delGTCA.
Alleles ; Erythrocytes ; Galactosemias* ; Heterozygote* ; UTP-Hexose-1-Phosphate Uridylyltransferase*

Galactosemia, a term that denotes the presence of galactose in the blood, is the name of rare inborn error of galactose metabolism due to a deficiency of the enzyme galactokinase (GALK), galactose-1-phosphate uridyltransferase (GALT) and uridine diphosphate-galactose 4-epimerase (GALE). GALT deficiency is the most common and shows the most severe clinical manifestation, including hepatomegaly, cataracts, and mental retardation. The main symptom of GALT deficiency is juvenile cataracts. GALE deficiency has two different forms; benign and severe forms. The benign form has no clinical significance, however, the severe form shows the same clinical manifestations as those of GALT deficiency.
Cataract ; Galactokinase ; Galactose ; Galactosemias* ; Hepatomegaly ; Intellectual Disability ; Metabolism ; Uridine ; UTP-Hexose-1-Phosphate Uridylyltransferase

OBJECTIVETo explore the genetic basis of two neonates suspected for galactosemia.

METHODSNext generation sequencing(NGS) was used to screen the whole exome of the neonates. Suspected mutation was validated by PCR and Sanger sequencing. Potential impact of novel mutation was predicted by using PolyPhen-2, MutationTaste and SIFT software.

RESULTSBoth neonates harbored compound heterozygous mutations of the GALT gene inherited from their parents. One has inherited two novel mutations c.564G>C(p.Q188H) and c.116A>T(p.D39V) respectively from his father and mother. The other has inherited mutations c.754C>T(p.Q252X) and c.904+1G>T from her father and mother, respectively.

CONCLUSIONThe galactosemia in the two neonates may be attributed to compound heterozygous mutations of the GALT gene. This is the first domestic report of using the NGS for the diagnosis of galactosemia.

Female ; Galactosemias ; diagnosis ; Heterozygote ; High-Throughput Nucleotide Sequencing ; methods ; Humans ; Infant, Newborn ; Male ; Mutation ; UTP-Hexose-1-Phosphate Uridylyltransferase ; genetics

Classical galactosemia is an autosomal recessive disorder of galactose metabolism, caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT). Buildup of galactose-1-phosphate is toxic at high levels and can damage the liver, brain, eyes, and other vital organs. The case presented here was that of an 11-day-old female infant who had elevated galatose levels upon initial neonatal screening test with persistent cholestatic jaundice, coagulopathy, and hepatomegaly. The patient was transferred due to aggravation of clinical symptoms including bleeding and jaundice. She had a delayed galactose free diet because of an inappropriate diagnosis. We quickly provided her with a lactose/ galactose-restricted diet as per her final diagnosis. Clinical and laboratory results were improved after a few days of treatment. For confirmatory testing for classical galactosaemia, we simultaneously analyzed for GALT enzyme activity and allele-specific PCR/fragments for seven mutations and two polymorphisms in the GALT gene. We were able to find several GALT-deficient and compound heterozygous mutations of the GALT gene.
Brain ; Diet ; Eye ; Female ; Galactose ; Galactosemias ; Galactosephosphates ; Hemorrhage ; Hepatomegaly ; Humans ; Infant ; Infant, Newborn ; Jaundice ; Jaundice, Obstructive ; Liver ; Neonatal Screening ; UTP-Hexose-1-Phosphate Uridylyltransferase