Galactosemia is an inherited metabolic disorder with a variable natural history. It can lead to severe systemic complications if neglected. The prognosis depends on various factors.

Acute neonatal illness is experienced by most patients. A reported lower enzyme activity leads to more severe presentation while newborn screening results in detection at more favorable stages of the disease. Clinical features include ^[1] having one or more of:

• Elevated liver enzymes
• Hypoglycemia
• Encephalopathy
• Sepsis
• Bleeding diathesis
• Cataract

A younger age of diagnosis and early introduction of dietary changes exert a positive effect on the natural history of galactosemia ^{[2] [3]}.

Despite dietary modifications, most of the galactosemic patients develop neurological and/or gonadal complications and are at risk of bone damage ^[1].

• Tremor: Most often seen in the second decade of life ^[1]
• General motor abnormality ataxia
• Seizures
• Dystonia
• Anxiety disorder: It is the most frequently reported mental problem and common in all age categories, usually after the second decade.
• ADHD, ASD: More likely before the second decade

• Premature ovarian insufficiency and subfertility ^[5]
• Cryptorchidism ^[6]
• Delayed psychosexual development ^[7]

Reduced bone mineral density ^[8]

The prognostic outcome of galactosemia depends on a number of factors ^[1]:

• Newborn screening: Associated with lower rates of neurological symptoms
• Enzyme activity: Enzyme acitivity <1% correlates with more severe mental and behavioral symptoms.
• Diet: Onset of diet in the first week of life is associated with a more favorable prognosis. Moreover, a relaxed diet (lactose free without any further restrictions) has been proven to be more beneficial than a strict diet for long-term clinical outcomes ^[9].