Deoxysphingolipid precursors indicate abnormal sphingolipid metabolism in individuals with primary and secondary disturbances of serine availability.

Patients with primary serine biosynthetic defects manifest with intellectual disability, microcephaly, ichthyosis, seizures and peripheral neuropathy. The underlying pathogenesis of peripheral neuropathy in these patients has not been elucidated, but could be related to a decrease in the availability of certain classical sphingolipids, or to an increase in atypical sphingolipids. Here, we show that patients with primary serine deficiency have a statistically significant elevation in specific atypical sphingolipids, namely deoxydihydroceramides of 18-22 carbons in acyl length. We also show that patients with aberrant plasma serine and alanine levels secondary to mitochondrial disorders also display peripheral neuropathy along with similar elevations of atypical sphingolipids. We hypothesize that the etiology of peripheral neuropathy in patients with primary mitochondrial disorders is related to this elevation of deoxysphingolipids, in turn caused by increased availability of alanine and decreased availability of serine. These findings could have important therapeutic implications for the management of these patients.

Polymorphisms in the fetal progesterone receptor and a calcium-activated potassium channel isoform are associated with preterm birth in an Argentinian population.

OBJECTIVE: To investigate genetic etiologies of preterm birth (PTB) in Argentina through evaluation of single-nucleotide polymorphisms (SNPs) in candidate genes and population genetic admixture. STUDY DESIGN: Genotyping was performed in 389 families. Maternal, paternal and fetal effects were studied separately. Mitochondrial DNA (mtDNA) was sequenced in 50 males and 50 females. Y-chromosome anthropological markers were evaluated in 50 males. RESULT: Fetal association with PTB was found in the progesterone receptor (PGR, rs1942836; P=0.004). Maternal association with PTB was found in small conductance calcium activated potassium channel isoform 3 (KCNN3, rs883319; P=0.01). Gestational age associated with PTB in PGR rs1942836 at 32-36 weeks (P=0.0004). MtDNA sequencing determined 88 individuals had Amerindian consistent haplogroups. Two individuals had Amerindian Y-chromosome consistent haplotypes. CONCLUSION: This study replicates single locus fetal associations with PTB in PGR, maternal association in KCNN3, and demonstrates possible effects for divergent racial admixture on PTB.