This is the name given to the neonate that at birth is covered by a shiny, transparent and tight membrane. Approximately 25 cases have been described in the literature.
Description
Collodion babies are usually premature and their perinatal morbidity and mortality are increased. At birth, the newborn is covered by a shiny, transparent and tight membrane reminiscent of a cellophane wrap. They present ectropion, eclabium and hypoplasia of the nasal and auricular cartilages. Suctioning and pulmonary ventilation may be impaired and transepidermal water losses and risk of infections increased.
The collodion baby is usually the presentation of IL and ICD. Autosomal dominant IL, Sjögren-Larsson syndrome, trichothiodystrophy, childhood Gaucher disease, neutral lipid storage disease, Conradi-Hünermann-Happle syndrome, Hay-Wells syndrome, and ectodermal dysplasias can also be occasionally manifest as collodion baby. In 10-24% of neonates the membrane spontaneously disappears and leaves the skin completely normal. In the past these cases were known as IL of the newborn, and today as BCAR. Some authors propose to speak of a collodion baby with self-improvement, because many patients, when they are reexamined in youth or in adulthood, present a variable degree of anhidrosis and heat intolerance and mild signs of ichthyosis , such as xerosis and fine scaling, especially in the armpits and neck. Both the light microscopy and the ultrastructure of the collodion baby are not specific. Therefore, it is preferable to defer the skin biopsy until the definitive phenotype has developed.
Mutations in the TGM1, ALOXE3 and ALOX12B genes have been identified in patients with BCAR, with ALOX12B being the most frequently mutated gene. In a series of 15 BCAR patients from Scandinavia , mutations were identified in ALOX12B in 67%, in ALOXE3 in 25%, and in TGM1 in 8.3%. In some patients, no mutations were found, so other genes must be involved. These mutations have been speculated to reduce enzyme activity in utero., but not live. In the uterus, where hydrostatic pressure is high, the chelation of water molecules converts the mutated enzyme into an inactive conformation. After birth, by lowering the pressure, the enzyme returns to its active form and increases its activity to levels sufficient to maintain the normal or minimally altered phenotype.
epidemiology
The exact prevalence is unknown. Approximately 25 cases have been described in the literature.
Etiology
SCHB is due to mutations in the TGM1, ALOXE3 or ALOX12B genes, which encode, respectively, transglutaminase 1, involved in the cornification of the stratum corneum, and arachidonate lipoxygenases 3 and 12 (R), involved in lipid metabolism. Transmission is autosomal recessive.