New Diagnostic Method for Lysosomal Acid Lipase Deficiency and the Need to Recognize Its Manifestation in Infants (Wolman Disease)

A female patient born (birth: 3.5 kg; 49 cm; 90th percentile) to non-consanguineous parents was taken to the local pediatrician in Mexico for rhinorrhea and fever in June 2012 when she was 2.5 months old. Her pediatrician noted hepatosplenomegaly (liver: 7 cm below the right costal margin at the mid-clavicular line; spleen 9 cm below the left costal margin), moderate jaundice, and evidence of growth failure (4.7 kg; 59 cm; 5th percentile) and the patient was admitted for further evaluation. The patient had 2 healthy, older brothers. In 2005, a sister developed similar symptoms at 3 months and died soon after. Laboratory examination was: hemoglobin: 8.8 g/dL; WBC: 29 × 109 cells/L; platelets: 107 × 109 cells/L; international normalized ratio: 4.5; partial thromboplastin time: 74.4 sec; alanine transaminase: 109 U/L; aspartate aminotransferase: 662 U/L; GGT: 256 U/L; total bilirubin: 1.8 mg/dL; direct bilirubin: 1.4 mg/dL; ammonia: 31 μmol/L; cholesterol: 200 mg/dL (5.1 mmol/L); triglycerides: 949 mg/dL (10.7 mmol/L). Foamy macrophages on peripheral blood smear are shown in Figure 1A. Gaucher and Niemann Pick were ruled out by a normal bone marrow examination and enzyme assay. Abdominal computed tomography revealed hepatosplenomegaly and bilateral adrenal calcifications (Fig. 1B).FIGURE 1: A, Peripheral blood smear showing foamy macrophages in lysosomal acid lipase deficiency. B, Abdominal computed tomography demonstrates hepatosplenomegaly and bilateral adrenal calcifications. C, Mutation analysis showed 2 mutations in the LIPA gene on chromosome 10: E8 c.894G>C, p.Gln298His, and E10 c.1024G>A, p.Gly342Arg.The infant was started on intravenous fluids, albumin, ursodeoxycholic acid, and fat-soluble vitamins and was transfused. Moderate anemia and thrombocytopenia persisted and liver failure progressed. The presumptive diagnosis of lysosomal acid lipase (LAL) deficiency was made because testing was not available at local laboratories. The patient continued to deteriorate and developed liver failure, severe anemia, thrombocytopenia and respiratory failure. Ascites, edema, and oliguria progressed to pulmonary edema and cardiogenic shock, resulting in death at approximately 5 months of age. LAL deficiency was confirmed post-mortem by documentation of deficient LAL activity from a dry blood spot (DBS) sample taken a few days before death and was analyzed at Massachusetts General Hospital (Neurogenetics Diagnostic Laboratory, Cambridge, MA). Mutation analysis (HIBM Research Group, Los Angeles, CA) revealed compound heterozygosity with 2 mutations, E8c.894G>C and E10c.1024G>A (Fig. 1C). DISCUSSION LAL deficiency is an autosomal recessive disease caused by deficiency or absence of LAL enzyme activity resulting from mutations in the lysosomal acid lipase A (LIPA) gene on chromosome 10 (1). This deficiency results in the accumulation of cholesteryl esters and triglycerides within the lysosome (1). LAL deficiency in infants, also known as Wolman disease, often present shortly after normal birth with diarrhea, hepatomegaly, and growth failure and die within the first year of life. Anemia, elevated transaminases, and bilateral adrenal calcification may also be seen. LAL-deficient infants have significant lipid accumulation in intestinal villi that impairs normal intestinal absorption and nutrition leading to malabsorption and growth failure (1). Given the rapid deterioration, LAL deficiency is a medical emergency and should be considered in the differential diagnosis for infants with acute gastroenterological signs/symptoms and growth failure (Table 1). In contrast, LAL deficiency in children and adults typically presents with elevated transaminases, hepatomegaly, microvesicular steatosis, and/or dyslipidemia, which often progresses to cirrhosis, liver failure, and accelerated atherosclerosis. The estimated incidence of LAL deficiency is widely variant depending on the population (1:4200–528,000) (2,3).TABLE 1: Typical findings and differential diagnoses of lysosomal acid lipase deficiency in infantsDiagnosis of LAL deficiency has typically been confirmed by demonstration of markedly decreased enzyme activity, in leukocytes/fibroblasts; however, both of these sample types are subject to sample handling deterioration during shipping and skin biopsies are required to obtain fibroblasts. The recent development of the LAL fluorometric enzymatic assay in DBS provides an alternative to traditional testing (4). A few drops of whole blood are collected on filter paper via capillary puncture or spotted after venipuncture. The blood saturates the paper and is then air-dried for a minimum of 4 hours. DBS samples are best stored refrigerated or frozen to enhance the stability before processing and should be shipped in low gas permeability plastic bags with desiccant. The DBS sample is not considered biohazardous, which can be a logistical advantage over other sample types when shipping to a reference laboratory. LAL enzyme activity in DBS is determined by subtracting LAL enzyme activity, in the presence of a specific inhibitor of LAL (Lalistat 2), from total lipase enzyme activity. DBS testing provides a minimally invasive, rapid, and low-cost method compared with traditional assays, and has been validated at multiple laboratories across the globe (Table 2).TABLE 2: Lysosomal acid lipase deficiency dry blood spot testing centers*There are no approved pharmacological therapies for LAL deficiency. Hematopoietic stem cell transplant and liver transplant have been attempted and reported in the literature. Three long-term survivors of hematopoietic stem cell transplant have been reported (maximal survival of >12 years after transplant), but complications related to poor growth and cognitive development were noted in all 3 cases (5–7). The high mortality rates may be related to the necessary intensive conditioning regimens in patients with significant preexisting liver disease (8). Liver transplantation may provide an option for those with liver failure, but extrahepatic organ involvement has also been reported resulting in morbidity and mortality in some cases (9). Clinical trials to assess the safety and efficacy of sebelipase alfa, a recombinant human lysosomal acid lipase, are underway (Synageva BioPharma Corp, Lexington, MA). There is an open-label trial for LAL-deficient infants presenting with growth failure within the first 6 months of life (http://www.clinicaltrials.gov/ct2/show/NCT01371825). Additionally, open-label, long-term data with sebelipase alfa from an ongoing phase 1/2 trial in LAL-deficient adults demonstrated a reduction from baseline of 56% in alanine transaminase, 40% in aspartate aminotransferase, 63% in low-density lioprotein cholesterol, and 47% in triglycerides, along with a 29% improvement in low-density lioprotein cholesterol after 1 year of treatment (P = 0.031 for each parameter) (10,11). Presently, a double-blind, placebo-controlled phase 3 trial in LAL-deficient patients (≥4 years of age) is enrolling (http://www.clinicaltrials.gov/ct2/show/NCT01757184). Unfortunately, this infant rapidly declined and diagnosis was only confirmed postmortem. The delay in diagnosis underscores the importance of disease awareness and rapid diagnosis. As such, clinicians should have heightened clinical suspicion in infants with the relevant symptoms/signs (Table 1), so that patients may have access to potential trials for LAL deficiency.