The ring 14 syndrome: clinical and molecular definition.

The ring 14 (r14) syndrome is a rare condition, whose precise clinical and genetic characterization is still lacking. We analyzed a total of 20 patients with r14 and another 9 patients with a linear 14q deletion. The ring was complete, with no apparent loss of chromosome material, in 6 cases; a terminal 14q deletion, varying in size from 0.65 to 5 Mb, was detected in the remaining 14 cases. Deleted ring chromosomes were 70% paternal and 30% maternal. UPD (14) was never detected. With respect to the linear 14q deletions, three were proximal, varying in size from 4 to 7.2 Mb, and six distal, varying in size from 4.8 to 20 Mb. The majority of the linear deletions were also of paternal origin, and UPD (14) was excluded in all cases. Clinically, the r14 syndrome was characterized by a recognizable phenotype, consisting of shortness of stature, a distinctive facial appearance, microcephaly, scoliosis, and ocular abnormalities, which included abnormal retinal pigmentation, strabismus, glaucoma, and abnormal macula. All patients except one had mental retardation. Drug-resistant epilepsy was another highly consistent finding. Aggressive and hyperactive behavior was noted in about half of the patients. Based on genotype-phenotype correlations, we could deduce that retinal abnormalities, epilepsy, microcephaly, and mental retardation map within the proximal 14q11.2-q12 region. Likewise, behavior disorders and scoliosis could be assigned to the 14q32 region.

An inherited large-scale rearrangement in SACS associated with spastic ataxia and hearing loss.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay is a neurodegenerative disorder characterized by early-onset, spastic ataxia and peripheral neuropathy, with or without mental retardation. The array of mutations in SACS has expanded worldwide after the first description in Quebec. We herein report the identification of an unconventional SACS mutation, a large-scale deletion sized approximately 1.5 Mb encompassing the whole gene, in two unrelated patients. The clinical phenotype of the patients was similar to more canonical ARSACS cases, though it is was complicated by the unusual presence of hearing loss. Our findings suggest that a "microdeletion" on chromosome 13q12 represents a novel allelic variant associated with ARSACS, stressing the need for an expanded testing in molecular diagnostic laboratories.

Sex reversal from functional disomy of Xp: prenatal and post-mortem findings.

Translocations involving the short arms of the X and Y chromosomes are uncommon and are often associated with anomalies in gonadal development. Segmental duplications of the X chromosome interfere with the formation of the testis in patients with a 46,XY karyotype. The gene products located within the duplicated segment, when present in double dose, may affect on male sex development. We report on a fetus with karyotype 46,XY,der (14)t(X;14) (p10;p10)dn. Attached to chromosome 14 is the entire short arm of the X chromosome. Therefore, the fetus is affected with a disomy of Xp, resulting in complete male to female sex reversal, as well as other structural defects. To the best of our knowledge, this is the first description of an XY fetus with a pure duplication of the entire short arm of X chromosome.

The effect of S-adenosylmethionine on CNS gene expression studied by cDNA microarray analysis.

High homocysteine (Hcy) together with low S-adenosylmethionine (SAM) levels are often observed in Alzheimer disease (AD), and this could be a sign of alteration of SAM/Hcy metabolism. It has already been shown that DNA methylation is involved in amyloid-beta-protein precursor (AbetaPP) processing and amyloid-beta(Abeta) production through the regulation of Presenilin 1 (PS1) expression and that exogenous SAM can silence the gene reducing Abeta. To investigate whether SAM administration globally influenced gene expression in the brain, we analysed 588 genes of the central nervous system in SK-N-BE neuroblastoma cells, with cDNA probes derived from untreated (DM; Differentiation Medium) or SAM treated (DM+SAM) cultures. In these conditions only seven genes were modulated by SAM treatment (and therefore by DNA methylation); three were up-regulated and four down-regulated, showing low levels of modulation.

S-adenosylmethionine/homocysteine cycle alterations modify DNA methylation status with consequent deregulation of PS1 and BACE and beta-amyloid production.

Few diseases are characterized by high homocysteine (HCY) and low folate and vitamin B12 blood levels. Alzheimer disease (AD) is among these. It has already been shown that DNA methylation is involved in amyloid precursor protein (APP) processing and beta-amyloid (A beta) production through the regulation of Presenilin1 (PS1) expression and that exogenous S-adenosylmethionine (SAM) can silence the gene reducing A beta production. Here we demonstrate that BACE (beta-secretase), as well as PS1, is regulated by methylation and that the reduction of folate and vitamin B12 in culture medium can cause a reduction of SAM levels with consequent increase in presenilin1 and BACE levels and with increase in A beta production. The simultaneous administration of SAM to the deficient medium can restore the normal gene expression, thus reducing the A beta levels. The use of deprived medium was intended to mimic a mild nutritional deficit involved in the onset of AD.