The following paper suggests that the nutritional status of Down Syndrome patients needs special attention. Through hair analysis, an abnormally low level of manganese, calcium and possibly copper in the DS patients was detected.
Individuals with Down syndrome and individuals with seizures may have lower levels of vitamin A, vitamin B1, folate, vitamin B12, vitamin C, magnesium, manganese, selenium, zinc, carnitine, carnosine, choline, and possibly serine. Excesses of copper and phenylalanine are also sometimes encountered in both disorders. In addition to common nutritional lower levels and excesses, disorders of metabolism involving vitamin B6, vitamin D, calcium, and tryptophan may play a common role.
Many chromosomal abnormalities are associated with Central Nervous System (CNS) malformations and other neurological alterations, among which seizures and epilepsy. Some of these show a peculiar epileptic and EEG pattern. Epileptic syndromes are frequently reported in chromosomal disorders.
Also see Epilepsy
This large study provides new leads for further evaluation of the role of paternal exposures in the etiology of DS.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1715649/pdf/ajhg00115-0026.pdf
The Down-Syndrome Epilepsy Foundation raised the question if myoclonic seizures in epileptics are linked to calcium disorders.