Aagenaes syndrome

Lore & Background

The first reported cases of Aagenaes syndrome were described in a study in 1968 from the southwest of Norway. Four out of five children born before 1939 died of bleeding in the first weeks of life. After the introduction of vitamin K in 1939, another four children were born; when these children received one dose of this vitamin, three of them died at the age of 5–9 months. The confirmed cause of death in one or two children in this group was bleeding. The remaining seven children, born in 1935 and in 1942–1966, who were part of the study published in 1968, were alive at the time.

Reader's Guide

Aagenaes syndrome is significant as a rare genetic disorder that illustrates the interplay between lymphatic and hepatic systems. Its genetic cause—a point mutation in the 5’-untranslated region of UNC45A—leads to loss of function and mislocalization of hepatobiliary transport proteins BSEP and MRP2, explaining the cholestasis. The condition's natural history shows that neonatal cholestasis often improves spontaneously during preschool and early school age, but recurs at intervals of two to six months. Untreated cholestasis can cause jaundice, itching, malabsorption, skeletal abnormalities, and bleeding. Lymphedema typically develops in the lower limbs in all patients by early childhood or adolescence, and untreated lymphedema can cause chronic tissue damage. While no cure exists, nutritional and vitamin supplements have improved outcomes, and liver transplantation is necessary in cases of complete liver failure or when remission does not occur by about 12 to 18 months. The decline in rickets, growth retardation, and neuropathy over recent decades is attributed to improved nutrition, vitamin supplementation, and cholestyramine.

Did You Know?

• Approximately one hundred people with Aagenaes syndrome are known, with more than half reported in southern Norway.
• Mutations in UNC45A are linked to Aagenaes syndrome, though the specific c.-98G>T variant is not consistently cited as the sole primary mutation in major medical references.
• Neonatal cholestasis in Aagenaes syndrome lasted no more than one year in some patients or until age 6 or 7 in others.
• Patients without observed liver cirrhosis had elevated levels of alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) compared to controls.

Clinical Presentation & Disease Progression

Aagenaes syndrome presents as a dual-system disorder affecting both the lymphatic and hepatobiliary systems from birth. The hallmark feature is congenital underdevelopment of lymphatic vessels, which produces generalized lymphedema. While swelling most commonly appears in the lower limbs during early childhood and adolescence, involvement of the upper extremities or chest is also documented, and persistent untreated edema can progress to chronic tissue damage. On the hepatic side, infants experience recurrent episodes of cholestasis that typically improve on their own during the preschool or early school years before recurring at intervals ranging from two to six months. Over time, the condition can advance toward hepatic cirrhosis, giant cell hepatitis, and fibrosis of the portal tracts. In the most severe presentations, patients progress to complete liver failure. Without intervention, cholestatic episodes bring jaundice, intense pruritus, and impaired absorption of dietary fats and fat-soluble vitamins, which in turn predispose affected children to skeletal deformities and a heightened risk of hemorrhagic complications.

Genetic Basis & Molecular Mechanism

The syndrome is inherited in an autosomal recessive pattern and traces back to a single point mutation, designated c.-98G>T, situated in the 5'-untranslated region of the UNC45A gene, which encodes the Unc-45 myosin chaperone A protein. This gene resides on chromosome 15q1,2. The mutation effectively abolishes normal protein function, and the downstream consequence appears to be the mislocalization of two critical hepatobiliary transporters: the bile salt export pump (BSEP) and the multidrug resistance-associated protein 2 (MRP2). Biochemical profiling of affected individuals reveals a characteristic trajectory. Bilirubin concentrations are markedly elevated during the first months of life but gradually normalize by around three or four years of age. By the teenage and young-adult years, serum bilirubin, bile acids, and transaminases generally fall within or near normal ranges. Nevertheless, patients without overt cirrhosis still show elevated alkaline phosphatase and gamma-glutamyl transferase levels, alongside reduced total protein, albumin, and creatinine, and a modestly raised fibrinogen. Serum albumin also tends to decline with advancing age in affected individuals, a trend not seen in healthy controls.

Epidemiology & Geographic Distribution

Aagenaes syndrome is an exceedingly rare condition, with roughly one hundred individuals identified worldwide to date. Despite its global occurrence, the disease shows a striking geographic concentration in southern Norway, where more than half of all reported cases have been documented. Patients have also been identified in other European countries and in the United States, confirming that the condition is not confined to a single population. The syndrome bears the name of Øystein Aagenæs, a Norwegian paediatrician, and is alternatively referred to as cholestasis-lymphedema syndrome (CLS). The earliest formal medical descriptions of the condition appeared in a 1968 study focused on children from the southwest of Norway. That foundational work catalogued a small cohort of affected children born between 1935 and 1966, providing the first systematic clinical picture of what would become recognized as a distinct genetic entity. The clustering of cases in a single Norwegian region has long suggested a founder effect, though the autosomal recessive inheritance pattern means that carriers can theoretically be found in any population.

Treatment & Historical Outcomes

No definitive cure for Aagenaes syndrome has yet been identified, but supportive management has substantially altered the disease trajectory. Nutritional support and targeted vitamin supplementation, particularly in young children, have produced meaningful improvements in clinical course, and cholestyramine has also been incorporated into the therapeutic regimen. A critical decision point arrives around twelve to eighteen months of age: if cholestasis has not entered remission by then, liver transplantation is generally deemed necessary at a later stage. Historical records underscore how far outcomes have improved. In the 1968 Norwegian cohort, four of five children born before 1939 succumbed to fatal bleeding within their first weeks of life. After vitamin K became available in 1939, three of the next four children still died between five and nine months, with hemorrhage confirmed as the cause in at least one or two cases. In more recent decades, cholestatic episodes have become shorter than those observed before 1970, and complications such as rickets, growth retardation, and neuropathy have declined, attributed to better nutritional practices and consistent supplementation. Nevertheless, serious liver disease remains a risk that current therapies cannot fully prevent.