Experimental and clinical studies have established that zinc metabolism is altered in individuals with Down syndrome (DS). The present study intends to evaluate the nutritional status of zinc in children with DS by determining their biochemical and dietary parameters. The investigation was carried out on a group of children with DS (n = 35) and compared with a control group (n = 33), both aging between 4 and 11 years. Weight-for-age, height-for-age, and weight-for-height indexes and diet were evaluated by using a 3-day dietary record. Zinc was evaluated in plasma, erythrocytes, and 24-h urine collection by using the method of atomic absorption spectroscopy. The frequency of short stature was higher in children with DS. Both groups presented high protein content, adequate concentrations of lipids and carbohydrates, and deficit in calories. Adequate zinc intake was observed in 40% of children with DS and in 67% of the control group. Zinc concentrations were significantly lower in plasma and urine and higher in erythrocytes of children with DS. The results allowed us to conclude that the altered zinc nutritional status of individuals with Down syndrome contributes to clinical disturbances that usually appear with aging in these patients.

C3 deficiency in humans is a rare disorder characterized by severe recurrent infections. We identified the mutations responsible for a complete homozygous C3 deficiency. Sequencing of the proband C3 cDNA (5067 bp) revealed the following alterations: (a) a silent G-->A transition at nucleotide 972; (b) a T-->C substitution at nucleotide 1001 resulting in a L314P transition; and (c) a stop codon in exon 13 caused by a G-->A substitution at position 1716. The presence of the same premature termination codon was confirmed in approximately half the clones obtained from the proband's paternal and maternal genomic DNAs. Finally, the proband produced approximately 20-fold less C3 mRNA than the normal control. Therefore, in addition to the fact that no functional protein will be synthesized in the deficient cells, this nonsense mutation may be associated with the low C3 mRNA levels.