| Galactokinase deficiency | |
|---|---|
| Other names | Galactosemia type 2 or GALK deficiency,[1] |
 | |
| Galactitol | |
| Specialty | Endocrinology  |
Galactokinase deficiency is an autosomal recessive metabolic disorder marked by an accumulation of galactose and galactitol secondary to the decreased conversion of galactose to galactose-1-phosphate by galactokinase.[2] The disorder is caused by mutations in the GALK1 gene, located on chromosome 17q24.[1] Galactokinase catalyzes the first step of galactose phosphorylation in the Leloir pathway of intermediate metabolism. Galactokinase deficiency is one of the three inborn errors of metabolism that lead to hypergalactosemia. The disorder is inherited as an autosomal recessive trait. Unlike classic galactosemia, which is caused by a deficiency of galactose-1-phosphate uridyltransferase, galactokinase deficiency does not present with severe manifestations in early infancy. Its major clinical symptom is the development of cataracts during the first weeks or months of life, as a result of the accumulation, in the lens, of galactitol, a product of an alternative route of galactose utilization. The development of early cataracts in homozygous affected infants is fully preventable through early diagnosis and treatment with a galactose-restricted diet. Some studies have suggested that, depending on milk consumption later in life, heterozygous carriers of galactokinase deficiency may be prone to presenile cataracts at 20–50 years of age.[3]
- ^ a b Online Mendelian Inheritance in Man (OMIM): Galactokinase Deficiency - 230200
- ^ Holton JB (1990). "Galactose disorders: an overview". J Inherit Metab Dis. 13 (4): 476–486. doi:10.1007/BF01799505. PMID 2122114. S2CID 20585794.
- ^ Kalaydjieva L, Perez-Lezaun A, Angelicheva D, et al. (November 1999). "A founder mutation in the GK1 gene is responsible for galactokinase deficiency in Roma (Gypsies)". Am. J. Hum. Genet. 65 (5): 1299–307. doi:10.1086/302611. PMC 1288282. PMID 10521295.