[show abstract][hide abstract] ABSTRACT: Progressive osseous heteroplasia (POH) is a rare genetic disorder characterized by dermal ossification during infancy and progressive ossification into deep connective tissue during childhood. POH is at the severe end of a spectrum of GNAS-associated ossification disorders that include osteoma cutis and Albright Hereditary Osteodystrophy (AHO). Here we describe two girls who have different clinical presentations that reflect the variable expression of GNAS-associated disorders of cutaneous ossification. Each girl had a novel heterozygous inactivating mutation in the GNAS gene. One girl had POH limited to the left arm with severe contractures and growth retardation resulting from progressive heterotopic ossification in the deep connective tissues. The other girl had AHO with widespread, superficial heterotopic ossification but with little functional impairment. While there is presently no treatment or prevention for GNAS-associated ossification disorders, early diagnosis is important for genetic counselling and for prevention of iatrogenic harm.
[show abstract][hide abstract] ABSTRACT: Variegate porphyria (VP), one of the acute hepatic porphyrias, results from an autosomal dominantly inherited deficiency of protoporphyrinogen oxidase (PPOX), the seventh enzyme in heme biosynthesis. Affected individuals can develop both cutaneous symptoms and potentially life-threatening neurovisceral attacks. Thirty unrelated VP index patients and families are currently known in the Swiss Porphyrin Reference Laboratory in Zürich. In 16 of a total of 24 genetically tested families, we detected a recurrent mutation in the PPOX gene, designated 1082-1083insC, reflecting a prevalence of 67%. Haplotype analysis revealed that 1082-1083insC arose on a common genetic background and, thus, represents a novel founder mutation in the Swiss population. Knowledge on the carrier status within a family does not only allow for adequate genetic counseling but also for prevention of the potentially life-threatening acute porphyric attacks. Hence, future molecular screening in Swiss VP patients might be facilitated by first seeking for mutation 1082-1083insC.
[show abstract][hide abstract] ABSTRACT: Erythropoietic protoporphyria (EPP) is an autosomal dominant disorder that results from a deficiency of ferrochelatase (FECH), the last enzyme in the heme biosynthetic pathway. The characteristic clinical symptoms usually manifest in early childhood on the sun-exposed areas of the body. They are due to protoporphyrin-induced photosensitivity and include pain, burning and stinging of the skin, followed by erythema and edema. Recently, the occurrence of predominantly seasonal palmar and palmoplantar keratoderma in patients with homozygous mutations in the FECH gene has been reported. These data suggested that palmoplantar keratoderma might be a clinical sign of EPP. Palmoplantar keratodermas (PPKs) are a heterogeneous group of genetic skin diseases and include a seasonal variant, erythrokeratolysis hiemalis et estivalis (EH), also known as keratolytic winter erythema. Because the skin symptoms in the latter disorder are similar to those reported for recessive EPP we examined the FECH gene in three unrelated Dutch Caucasian patients with a previous diagnosis of EH in whom mutations in several other genes had been excluded. However, sequencing analysis of the entire coding regions and the adjacent splice sites of the FECH gene in these individuals revealed absence of mutations. Hence, our data largely exclude the possibility that FECH mutations might be responsible for the palmoplantar skin phenotype observed in EH.