For many years, HFE was the only known gene associated with haemochromatosis, and the term "hereditary haemochromatosis" was used to describe haemochromatosis type 1. However, many different genetic associations with this condition are now known. The older the text, or the more general the audience, the more likely that HFE is implied. "Haemochromatosis" has also been used in contexts where a genetic cause for iron accumulation had not been known. In some cases, however, a condition that was thought to be due to diet or environment was later linked to a genetic polymorphism, as in African iron overload. History
In 1847, Virchow described a golden brown granular pigment that was soluble in sulfuric acid and produced red ash on ignition. The disease was first described in 1865 by Armand Trousseau in a report on diabetes in patients presenting with a bronze pigmentation of their skin. Two years later, Perls developed the first practical method for the analysis of iron in tissue. Despite Trousseau did not associate diabetes with iron accumulation, the recognition that infiltration of the pancreas with iron might disrupt endocrine function resulting in diabetes was made by Friedrich Daniel von Recklinghausen in 1890. In 1935, English gerontologist Joseph Sheldon described the cases of haemochromatosis. He established this as the name of the disorder and his detailed monograph.
Congenital hereditary corneal dystrophy (CHED) is a form of corneal endothelial dystrophy that presents at birth. CHED was previously subclassified into two subtypes: CHED1 and CHED2. However in 2015, the International Classification of Corneal Dystrophies (IC3D) renamed the condition "CHED1" to become posterior polymorphous corneal dystrophy, and renamed the condition "CHED2" to become, simply, CHED. Consequently, the scope of this article is restricted to the condition currently referred to as CHED

Signs and symptoms
CHED presents congenitally, but has a stationary course. The cornea exhibits a variable degree of clouding: from a diffuse haze, to a "ground glass" appearance, with occasional focal gray spots. The cornea thickens to between two and three times is normal thickness. Rarely, sub-epithelial band keratopathy and elevated intraocular pressure occur. Patients have blurred vision and nystagmus, however it is rare for the condition to be associated with either epiphora or photophobia with this. Genetics
CHED exhibits autosomal recessive inheritance, with 80% of cases linked to mutations in SLC4A11 gene. The SLC4A11 gene encodes solute carrier family 4, sodium borate transporter, member 11. Pathology
Histologically, the Descemets membrane in CHED becomes diffusely thickened and laminated. Multiple layers of basement membrane-like material appear to form on the posterior part of Descemets membrane. The endothelial cells are sparse - they become atrophic and degenerated, with many vacuoles. The corneal stroma becomes severely disorganised; the lamellar arrangement of the fibrils becomes disrupted. Diagnosis
Management
Management of CHED primarily involves corneal transplantation. The age that corneal transplantation is required is variable, however, it is usually necessary fairly early in life.