The classic presentation is vomiting and failure to gain weight in a newborn with chalky bilateral adrenal calcifications on imaging, with life expectancy rarely exceeding a year.

Because of these digestive complications, affected infants usually fail to grow and gain weight at the expected rate for their age (failure to thrive).

[2] As the disease progresses in infants, increasing fat accumulation in the liver leads to other complications including yellowing of the skin and whites of the eyes (jaundice), and a persistent low-grade fever.

An ultrasound examination shows an accumulation of chalky material (calcification) in the adrenal gland in about half of infants with LAL-D.[2][4] Complications of LAL-D progress over time, eventually leading to life-threatening problems such as extremely low levels of circulating red blood cells (severe anemia), liver dysfunction or failure, and physical wasting (cachexia).

[3] When LAL functions normally, it breaks down cholesteryl esters and triglycerides in low density lipoprotein particles into free cholesterol and free fatty acids that the body can reuse; when LAL doesn't function, cholesteryl esters and triglycerides build up in the liver, spleen and other organs.

[2][5] The accumulation of fat in the walls of the gut and other organs in leads to serious digestive problems including malabsorption, a condition in which the gut fails to absorb nutrients and calories from food, persistent and often forceful vomiting, frequent diarrhea, foul-smelling and fatty stools (steatorrhea), and failure to grow.

[2] Lysosomal acid lipase deficiencies occur when a person has defects (mutations) in both copies of the LIPA gene.

[2] Liver biopsy findings will generally show a bright yellow-orange color, enlarged, lipid-laden hepatocytes and Kupffer cells, microvesicular and macrovesicular steatosis, fibrosis, and cirrhosis.

[2] Infants with LAL deficiencies typically show signs of disease in the first weeks of life and if untreated, die within 6–12 months due to multi-organ failure.

Jewish infants of Iraqi or Iranian origin appear to be most at risk based on a study of a community in Los Angeles in which there was a prevalence of 1 in 4200.

[13] Before the approval of that drug, as of 2009 the two oldest survivors of LAL-D in the world were then aged 4 and 11; both of them had been treated with hematopoietic stem cell treatment.