Answer by  
                                                                                          LeheckaG (1826)
                                                            
                          
                          
                                                          Harlequin-type ichthyosis is caused by a genetic-disorder, either inherited or a mutation;
 milder cases might be caused by a Vitamin-A deficiency.
 
 In severe cases, the skin's keratin-layer thickens and appears like diamond-shaped scales.
 
 It can be diagnosed either via amniocentisis of by modern (3D) ultra-sound techniques.
 
 Isotretinoin(Isotrex) can be used to treat it; previously victims died within a few days.