Screening for congenital hypothyroidism: the significance of threshold limit in false-negative results.

Context: In our neonatal program, a number of infants with congenital hypothyroidism (CH) had escaped diagnosis, when a spot RIA-TSH value of 20 mU/liter whole blood was used as a cutoff point.

Objective: The objective of the study was to find out prospectively the additional number of newborns with CH if the TSH cutoff point is lowered to 10 mU/liter.

Population And Methods: The study included 311,390 screened newborns.

Primary open angle glaucoma due to T377M MYOC: Population mapping of a Greek founder mutation in Northwestern Greece.

Background: Mutations in the MYOC gene have been shown to explain 5% of unrelated primary open angle glaucoma (POAG) in different populations. In particular, the T377M MYOC mutation has arisen at least three separate times in history, in Great Britain, India, and Greece. The purpose of this study is to investigate the distribution of the mutation among different population groups in the northwestern region of Greece.

Are GJB2 mutations an aggravating factor in the phenotypic expression of mitochondrial non-syndromic deafness?

Hearing impairment is a frequent condition, and genes have an important role in its etiology. The majority of hearing loss occurs in non-syndromic form, with deafness being the only clinically recognizable feature. More than 60 nuclear genes or loci have been shown to be involved in non-syndromic hearing loss, but mutations in mitochondrial DNA also cause hearing impairment.

Investigating the impact of the Down syndrome related common MTHFR 677C>T polymorphism in the Danish population.

Chromosomal aneuploidy consists the leading cause of fetal death in our species. Around 50% of spontaneous abortions until 15 weeks of gestational age are chromosomally aneuploid, with trisomies accounting for 50% of the abnormal abortions. Trisomy 21 is the most common chromosome abnormality in liveborns and is usually the result of nondisjunction of chromosome 21 in meiosis in either oogenesis or spermatogenesis.

Hypothesizing an ancient Greek origin of the GJB2 35delG mutation: can science meet history?

One specific mutation of the GJB2 gene that encodes the connexin 26 protein, the 35delG mutation, has become a major interest among scientists who focus on the genetics of nonsyndromic hearing loss. The mutation accounts for the majority of GJB2 mutations detected in Caucasian populations and represents one of the most frequent disease mutations identified so far. The debate was so far between the arguments whether or not the 35delG mutation constitutes a mutational hot-spot or a founder effect; however, it was recently clarified that the latter seems the most likely.

Easy, rapid, and cost-effective methods for identifying carriers of recurrent GJB2 mutations causing nonsyndromic hearing impairment in the Greek population.

A variety of techniques have been developed for screening the GJB2 gene for known and unknown mutations, especially the most common mutation in the Caucasian population, the c.35delG. Other mutations that have been so far characterized in the GJB2 gene seem to have different geographical distributions, and therefore there is an interest in identifying recurrent mutations specific for each population and developing easy and rapid screening techniques.

The A1555G mitochondrial DNA mutation in Greek patients with non-syndromic, sensorineural hearing loss.

Mitochondrial DNA mutations are undoubtedly a factor that contributes to sensorineural, non-syndromic deafness. One specific mutation, the A1555G, is associated with both aminoglycoside-induced and non-syndromic hearing impairment. The mutation is considered to be the most common of all mitochondrial DNA deafness-causing mutations but its frequency varies between different populations.

Serum copper and zinc levels in healthy greek children and their parents.

The aim of this study was to investigate whether there is a correlation between copper (Cu) and zinc (Zn) levels in children and their parents, considering their nutritional habits. Cu and Zn concentrations were measured by flame atomic absorption spectrophotometry in the serum of 66 healthy children, aged 3-14 years, and their parents, residing in a region of Greece (Thrace). Cu levels were higher in mothers than those in fathers, but they were lower in both parents than those in children.

Early effects of sodium valproate monotherapy on serum paraoxonase/arylesterase activities.

Objective: Valproic acid (VPA) treatment and paraoxonase1/arylesterase (PON1/Aryl) activities are related to the production of free radicals. Our aim was to study the PON1/Aryl activities in children on VPA therapy.

Material And Methods: Thirty-two children with seizures and 30 healthy child volunteers took part.

Strong linkage disequilibrium for the frequent GJB2 35delG mutation in the Greek population.

Approximately one in 1,000 children is affected by severe or profound hearing loss at birth or during early childhood (prelingual deafness). Up to 40% of congenital, autosomal recessive, severe to profound hearing impairment cases result from mutations in a single gene, GJB2, that encodes the connexin 26 protein. One specific mutation in this gene, 35delG, accounts for the majority of GJB2 mutations detected in Caucasian populations.

Sudden hearing loss in a family with GJB2 related progressive deafness.

Mutations of GJB2, the gene encoding connexin 26, have been associated with prelingual, sensorineural hearing loss of mild to profound severity. One specific mutation, the 35delG, has accounted for the majority of mutations detected in the GJB2 gene in Caucasian populations. Recent studies have described progression of hearing loss in a proportion of cases with GJB2 deafness.

Cohen syndrome resulting from a novel large intragenic COH1 deletion segregating in an isolated Greek island population.

Cohen syndrome, caused by mutations in the COH1 gene, is an autosomal recessive disorder consisting of mental retardation, microcephaly, growth delay, severe myopia, progressive chorioretinal dystrophy, facial anomalies, slender limbs with narrow hands and feet, tapered fingers, short stature, kyphosis and/or scoliosis, pectus carinatum, joint hypermobility, pes calcaneovalgus, and, variably, truncal obesity. Here, we describe the clinical and molecular findings in 14 patients from an isolated Greek island population. The clinical phenotype was fairly homogeneous, although microcephaly was not constant, and some patients had severe visual disability.

Pathologic, radiographic and molecular findings in three fetuses diagnosed with HEM/Greenberg skeletal dysplasia.

Background: Greenberg skeletal dysplasia is a very rare, autosomal recessive, in utero, lethal chondrodystrophy for which only eight index cases of diverse ethnic origin have been reported so far. The defect is associated with a defect in cholesterol biosynthesis and due to mutations in the gene encoding the lamin B receptor (LBR).

Methods: A familial case of three fetuses of a consanguineous Greek couple is presented including prenatal, physical, radiographic, histopathologic, and molecular genetic findings.

Melatonin and immunomodulation: connections and potential clinical applications.

Melatonin is the main hormone secreted by the pineal gland in the human brain. It has a strong impact on the sleep-wake cycle and is considered a general modulator of the human circadian rhythm. Apart from these well-established properties, melatonin possesses immunomodulatory, antioxidative and antiinflammatory properties.

Erythrocyte membrane Na+,K+-ATPase and Mg2+-ATPase activities in subjects with methylenetetrahydrofolate reductase (MTHFR) 677 C-->T genotype and moderate hyperhomocysteinaemia. The role of L-phenylalanine and L-alanine.

Background: Increased homocysteine (Hcy) blood levels are correlated with vascular and neurological problems. The aim of our study was to investigate erythrocyte membrane Na(+),K(+)-ATPase and Mg(2+)-ATPase activities in patients with methylenetetrahydrofolate reductase (MTHFR) 677 C-->T genotype.

Methods: Blood was obtained from 25 patients before and after folic acid supplementation and from controls (n=30) once.

Calcium and vitamin D metabolism in hypocalcemic vitamin D-resistant rickets carriers.

Background/aims: Hypocalcemic vitamin D-resistant rickets (HVDRR) is a rare monogenic autosomal recessive disorder associated with mutations in the gene of the vitamin D receptor (VDR), the mediator of 1,25(OH)2D3 action. Although many investigations have discussed the clinical manifestations and molecular etiology of this disease, only a few have investigated the biochemical and hormonal status of heterozygous HVDRR. The aim of the current work was to investigate the profile of selected biochemical and hormonal parameters related to the vitamin D endocrine system in a large number of HVDRR heterozygotes.

Erythrocyte membrane acetylcholinesterase activity in subjects with MTHFR 677C-->T genotype.

Background: Increased homocysteine (Hcy) blood levels are correlated with vascular and neurological problems.

Aim: The aim of the present study was to investigate erythrocyte membrane acetylcholinesterase (AChE) activity in subjects with the MTHFR C677T genotype in relation to Hcy.

Methods: Blood was obtained from 22 individuals with the MTHFR C677T genotype before and after folic acid supplementation and once from controls (n = 30).

The effect of aspartame metabolites on human erythrocyte membrane acetylcholinesterase activity.

Studies have implicated aspartame (ASP) with neurological problems. The aim of this study was to evaluate acetylcholinesterase (AChE) activity in human erythrocyte membranes after incubation with the sum of ASP metabolites, phenylalanine (Phe), methanol (met) and aspartic acid (aspt), or with each one separately. Erythrocyte membranes were obtained from 12 healthy individuals and were incubated with ASP hydrolysis products for 1 h at 37 degrees C.