Complex I (C I) deficiency is a frequent cause (30%) of pediatric mitochondrial disease, presenting with a phenotypic spectrum from lethal multisystem disorder to mild myopathy. More than 80% of the patients present neurologic symptoms. The diagnosis is based on biochemical analysis of C I-activity in muscle or fibroblasts. The molecular diagnosis is difficult to establish due to a large number of candidate genes (>80). Therefore prognostic evaluation, genetic counseling, prenatal diagnosis and also therapeutic approaches are difficult.

Aim: Mitochondrial diseases (incidence of 1: 8 000 in children) are attributed to isolated or combined respiratory chain complex (RCC) deficiencies. With around 25%, isolated RCC I-deficiency is the most common form. Clinically the patients present a heterogeneous spectrum which can be multi systemic (e.g. neonatal lactic acidosis, Leigh syndrome) or with distinct symptoms (e.g. ataxia, myopathy). RCC I is composed of 45 different subunits which are encoded by nuclear DNA (n=38) and mitochondrial DNA (n=7). The high number of genes involved hampers the search for the molecular basis of RCC I deficiency. Since in routine diagnostics only part of the mtDNA is analyzed, causal mutations can be identified in less than 10% of the pediatric patients.

In contrast to the granitoids of the ultrametamorphic basement of northern Sardinia, Hercynian intrusive granites exist in southern Sardinia in low-grade metamorphic surroundings. In this area, endogenous cassiterite-bearing vein deposits and molybdenumtungsten mineralizations occur adjacent to the granite massifs of the Quirra (3), Arburese (4) and Monte Linas (5). In comparison, the intrusives of the Sarrabus (1) and San Vito (2) seem to be barren.