A molecular approach to galactosemia

Area of Science:

• Genetics
• Biochemistry
• Metabolic Disorders

Background:

• Classical galactosemia (G/G) results from absent galactose-1-phosphate uridyltransferase (GALT) activity, while Duarte/Classical (D/G) presents with partial impairment.
• While neonatal mortality is reduced, long-term G/G complications include growth issues, ovarian failure, speech deficits, and neurological problems.
• Over 32 GALT gene variants are known, with 9 demonstrating impaired GALT activity in cellular models.

Purpose of the Study:

• To determine the prevalence of two specific GALT gene mutations, Q188R and N314D.
• To investigate the clinical outcome associated with Q188R homozygosity.
• To define the biochemical phenotype and prevalence of the N314D mutation.

Main Methods:

• Population screening using polymerase chain reaction (PCR) to detect Q188R (HpaII site) and N314D (AVA II site) GALT gene mutations.
• Analysis of clinical outcomes in patients with G/G galactosemia, focusing on Q188R homozygosity.
• Biochemical assessment of patients carrying the N314D mutation.

Main Results:

• The Q188R mutation was found in 62% of 107 predominantly Caucasian G/G galactosemia patients.
• Homozygosity for Q188R correlated with poorer clinical outcomes in a subset of patients.
• The N314D mutation showed a strong association with the Duarte biochemical phenotype.

Conclusions:

• Q188R is a prevalent mutation in G/G galactosemia, and its homozygous state can negatively impact clinical outcomes.
• N314D is a significant mutation strongly linked to the Duarte biochemical phenotype, aiding in understanding galactosemia variants.