Study On Clinical Character And Genetic Model Of Dyschromatosis Symmetrical Hereditaria And Freckle

Study on clinical character and genetic model ofDyschromatosis Symmetrical Hereditaria and FrecklePigmentary inherited disease, which occupies a part of population ingenodermatosis, is disease of monogenic inheritance. The genes of some diseases havebeen identified, such as Xeroderma, incontinentia pigmentation and PJS syndromes. Butthe pattems of inheritance and candidate genes of some pigmntary diseases have notbeen clarified so far In this st-Udy, we tried to demonstrate the genetic mode of them bythe pedigree analyses of freckles and DSH, namely, independent heredity or linkageheredity In addition, the result will be helpful for the study of the pathogenic genes ofthese diseases.Freckles are common brown guttate pigmeniations on face and can extend to bothuPper extremities or all over the body. At present, the foreign reports show that Freck1eis the followed trait of some diseases such as xeroderma pigmeniosa, incontineniiapigmenti and PJS syndrome. As for genetic model has been unknown. DSH isatosomal dominam inheritance disease with properties of synunetric mixedpigmentation and depigmen skin eruptions on backs of extremities. The candidate genesand chromosomaI location of DSH have not been determined.We analyzed genetic type, clinical situation, histopathology and clinicalexamination of tWo freckle families and three dyschromatosis symmetrical hereditallafaInilies with the method of family investigation. The results showed that: l ) of the twofreckle families, the episodes of male and female of the two freckle pedigrees wereidentical and the incidence rate was 50% in every generation. So we concluded thatfreckle is an auosomal dominan inheritance; all skin eruPtion found on face, werebrown pigment plaques and are as large as needlepoint or needle head. There is ahomozygote families in the tWo families, whose skin eruPtion fall in on the both upperextremities and trunk. Furthermore, their mothers are all sporadic cases, which suggested that the inheritance of the two families was incomplete penetrance and diffferent expressity and mothers may be carrier of fleck gene. Histopathology showed apparently the hyperpigmentation and no nevus cells were found in the basal layer and the above layers. Melanocytes were found in the above of dermis, which differentiated with freckle-like mole. Differing from the foreign reports, the disease has no linkage phenomena because of the normality of the health examination of the patients. In addition, the disease is not a follow symptom of other diseases and an independent disease. 2) There are patients in every generation on the three DSH families (total number of 130 in four generations). About half of their children suffered from DSH and the episodes of male and female were identical. This property is consistent with autosomal dominant inheritance; Skin eruption, which like pigmentation locus as large as needlepoint or bean and reticular depigmentation plaque, occurs mainly on extremities. Pigment deposition is similar to freckle; particularly, skin eruption of analogical freckle on the face. Histopathology showed apparently the increase of melanin granules in the basal layer and no nevus cells were found. Melanocytes were found in the above of dermis. Systemic health examination is normal. 3) Comparative analytical results of two diseases indicated that their skin eruptions began to appear all from the child. Skin eruption on face was similar to freckle, which of color and big and small was very alike. Pathology of skin eruption was not different between the two diseases and their genetic models were all autosomal dominant inheritance. But property, distribution and provocative factors of skin eruption were different between the two diseases. So we suppose that freckle and DSH can exist identical pathogenic gene.