Multiple endocrine neoplasia 2 in Cyprus: evidence for a founder effect

PURPOSE

Multiple endocrine neoplasia type 2 (MEN2) affects patients with RET proto-oncogene mutations. This cohort study refers to patients who were diagnosed with familial medullary thyroid carcinoma (MTC) and underwent RET genetic testing in Cyprus between years 2002 and 2017.

METHODS AND PATIENTS

Forty patients underwent RET testing by Sanger sequencing of exons 10-11 and 13-16. Genotyping with STR genetic markers flanking the RET gene along with Y-chromosome genotyping and haplogroup assignment was also performed.

RESULTS

RET mutations were identified in 40 patients from 11 apparently unrelated Cypriot families and two non-familial sporadic cases. Nine probands (69.2%) were heterozygous for p.Cys618Arg, one (7.7%) for p.Cys634Phe, one (7.7%) for the somatic delE632-L633 and two (15.4%) for p.Met918Thr mutations. The mean age at MTC diagnosis of patients carrying p.Cys618Arg was 36.8 ± 14.2 years. The age of pheo diagnosis ranged from 26 to 43 years and appeared simultaneously with MTC in 5/36 (13.9%) cases. The high frequency of the p.Cys618Arg mutation suggested a possible ancestral mutational event. Haplotype analysis was performed in families with and without p.Cys618Arg. Six microsatellite markers covering the RET gene and neighboring regions identified one core haplotype associated with all patients carrying p.Cys618Arg mutation.

CONCLUSIONS

The mutation p.Cys618Arg is by far the most prevalent mutation in Cyprus followed by other reported mutations of variable clinical significance. The provided molecular evidence speculates p.Cys618Arg mutation as an ancestral mutation that has spread in Cyprus due to a possible founder effect.

No association of the ACTN3 gene R577X polymorphism with endurance performance in Ironman Triathlons

Alpha-actinins are major structural components of the Z-discs in skeletal muscle. Alpha-actinin 3 is encoded by the ACTN3 gene and is expressed only in type II muscle fibres. Homozygosity for the nonsense mutation, 577X, within ACTN3 results in deficiency of alpha-actinin-3 but does not result in an abnormal muscular phenotype. Previous research has found an association of the 577R allele with sprinting and/or power performance. It has also been suggested that the 577X allele may confer an advantage during endurance events. Four hundred and fifty seven Caucasian male triathletes who completed either the 2000 and/or 2001 226 km South African Ironman Triathlons, and 143 Caucasian controls, were genotyped for the R577X mutation within the ACTN3 gene. There were no significant differences in either the genotype (P = 0.486) or allele (P = 0.375) frequencies within the fastest, middle of the field or slowest Caucasian male finishers and the control population. In conclusion, the R577X polymorphism within the ACTN3 gene was not associated with ultra-endurance performance in the 2000 and 2001 South African Ironman Triathlons.

Spectrum and prevalence of prothrombotic single nucleotide polymorphism profiles in the Greek Cypriot population

BACKGROUND

This study was performed to establish the allele, genotype and genotype combination/SNP (single nucleotide polymorphism) profile frequencies in the general population of Cyprus for 6 genes implicated in thrombotic disorders. The genes with their respective functional polymorphisms were the following: factor V (G1691A), prothrombin/factor II (G20210A), methylenetetrahydrofolate reductase (C677T), platelet glycoprotein receptor IIIa (P1A1/A2), b-fibrinogen (G/A-455) and plasminogen activator inhibitor-type 1 (4G/5G).

METHODS

DNA samples from 121 unrelated individuals were used for this epidemiological study. The polymerase chain reaction followed by restriction digestion were used to genotype the 6 different polymorphic loci. Allele and genotype frequencies were established and shown to be in Hardy-Weinberg equilibrium.

RESULTS

Mutant allele frequencies for the 6 genes were as follows: factor V-4%, prothrombin-2%, methylenetetrahydrofolate reductase -39%, platelet glycoprotein receptor IIIa-16%, beta-fibrinogen-17% and plasminogen activator inhibitor - type 1-46%. Combined defects occurred which may increase the risk for vascular events, 33% of individuals (39/118) had 3 or more of the above mutations.

CONCLUSIONS

As in other European populations, prospective case-control studies to estimate the risk for deep vein thrombosis (DVT) and ischemic episodes with respect to genetic and environmental risk factors should be performed. Thrombophilia screening should be applied for primary and secondary prevention of thrombotic episodes in susceptible individuals on the island of Cyprus. Individuals targeted for such screening include those with the following: a positive family history for thrombosis; a previous DVT or other ischemic episode; prior exposure to circumstantial risk factors and in the presence of echolucent plaques.

Genetic polymorphisms of the apolipoprotein A-IV in a Greek population and their relation to plasma lipid and lipoprotein levels

Apolipoprotein (apo) A-IV is a protein component of triglyceride-rich lipoproteins and high-density lipoproteins (HDL). In this study, two common genetic polymorphisms of the apoA-IV gene [codons 347(allele A and T) and 360 (allele 1 and 2)] were investigated in Greek patients with hyperlipidaemia and in healthy individuals matched for age, sex and smoking habits. In both study populations we evaluated the effect of these polymorphic sites on lipid and lipoprotein plasma levels and the body mass index (BMI). The frequencies of the 1/1 and 1/2 genotypes in codon 360 were 0.94 and 0.06 in hyperlipidemic patients and 0.92 and 0.08 in the control population, respectively. The frequencies of the A/A, A/T and T/T genotypes in codon 347 were 0.62, 0.34 and 0.04 in hyperlipidemic patients and 0.59, 0.33 and 0.08 in the control population, respectively. None of the above genotype frequency differences between the study populations reached statistical significance. The control population was not affected by any polymorphism of the apo A-IV gene. Hyperlipidaemic patients, carriers of the allele 2 (1/2 genotype), had significantly lower plasma triglyceride levels than carriers of the allele 1 (p = 0.03). Genetic variation in codon 347 had no influence on lipid and lipoprotein plasma levels. None of the polymorphisms at codons 360 and 347 affected the BMI. In conclusion, this study describes for the first time the genotype frequencies for polymorphic sites in codons 360 and 347 of the apo A-IV gene in a Greek population and suggests that the presence of the allele 2 is associated with lower plasma triglyceride levels in hyperlipidaemic patients.

Data on nine STR loci used for forensic and paternity testing in the Greek Cypriot population of Cyprus

Allele frequencies for the nine STRs included in the AMPFlSTR kit were obtained from a sample of 152 unrelated Greek Cypriot from the Mediterranean island of Cyprus

Characterization and geographic distribution of the low density lipoprotein receptor (LDLR) gene mutations in northwestern Greece

Familial Hypercholesterolaemia (FH) is a clinical syndrome characterised by elevated serum total cholesterol levels due to an increase in low density lipoprotein (LDL) cholesterol, by tendon xanthomata and clinical manifestations of ischaemic heart disease in early life. Typically, it results from mutations in the low-density lipoprotein receptor (LDLR) gene. So far, over 600 mutations have been reported for the LDLR gene and account for FH. The nature of LDLR gene mutations is different in various ethnicities and has also regional distribution within each ethnicity. Eleven mutations have already been described in the Greek population. This report describes seven LDLR gene mutations accounting for FH in Northwestern Greece (81T>G, 517T>C, 858C>A, 1285G>A, 1352T>C, 1646G>A and 1775G>A) and their geographic distribution. We have recently described one of these mutations (1352T>C) as a novel point mutation in a Greek family originating from Northwestern Greece. Furthermore, two previously identified mutations (81T>C, 1775G>A) were also detected in the Greek FH patients for the first time. The 1775G>A mutation was responsible for all the homozygous patients in our area, indicating a founder effect. These data will favor the development of tailed information and screening programs in Northwestern Greece for the primary prevention of cardiovascular disease in FH patients.

Geographical clustering of low density lipoprotein receptor gene mutations (C292X; Q363X; D365E & C660X) in Cyprus

In Cyprus, no data are yet available on the frequencies of clinically diagnosed FH patients. Further, until now, familial hypercholesterolaemia in Cyprus had not been studied at the molecular level to determine the nature or frequency of LDLR gene mutations. Being a relatively homogeneous population, we anticipated that a few founder mutations would predominate on the island. In the present study, three previously identified LDLR gene mutations were found to cosegregate with high LDL cholesterol levels in 23 unrelated, clinically diagnosed families with FH. Geographical clustering of each of these LDLR gene mutations was indicated, a phenomenon arising from low migration rates and high inbreeding. The latter cultural practices account for the discovery of a homozygous FH sib pair whose parents are carriers of the same mutation. Microsatellite and intragenic haplotype analysis in this FH population, suggested that the families which shared the same LDLR gene mutation have a common origin. This is supported by their relative geographical distribution. Thirty young FH individuals were also offered presymptomatic diagnosis which should facilitate the prevention of premature coronary artery disease. Finally, results from this study support the suggestion that the formation of tendon xanthomata in FH patients may be under environmental influence. Hum Mutat 15:380, 2000.

Greek Cypriot allele and genotype frequencies for Amplitype PM-DQA1 and D1S80 loci

A sample from the Greek Cypriot population was typed at seven forensically important PCR-based loci: LDLR, GYPA, HBGG, D7S8, GC, HLA-DQA1, and D1S80. The results showed that all loci meet Hardy-Weinberg expectations and that there is no evidence for association of alleles between loci. Allelic frequency distributions at all loci, except HLA-DQA1 and two D1S80 alleles, were similar to those of U.S. Caucasians. Greek Cypriot population databases have been created and can be used for forensic analyses to estimate the frequency of a multiple locus DNA profile.

Novel trinucleotide deletion in Fabry's disease

We describe the molecular characterization of a novel, in-frame deletion that is located in exon 7 of the alpha-galactosidase A gene in a patient with Fabry's disease. The 3-bp deletion we identified, besides the typical severe clinical features, also expresses diffuse facial telangiectasias, which is a new cutaneous marker of Fabry's disease.

Underexpression of the apolipoprotein E2 and E4 alleles in the Greek Cypriot population of Cyprus

Apolipoprotein E (APOE) plays an important role in the multifactorial etiology of both cardiovascular disease and Alzheimer's disease. Polymerase chain reaction (PCR) was used to investigate the APOE gene polymorphism in 335 unrelated Greek Cypriots living on the island of Cyprus. For the most common APOE genotypes, the Greek Cypriots followed the general Caucasian European pattern of having higher genotypic frequencies of E3/3, followed by E3/4, and then E2/3. Among the European populations compared, Greek Cypriots exhibited the lowest relative frequency of the E3/4 genotype (12.83%). Also, the relative frequencies of the E2 and E4 alleles in Greek Cypriots were among the lowest around the world (5.4% and 7.0%, respectively). This was also demonstrated by using the complete and the average clustering methods of analysis where the APOE allele relative frequencies in Greek Cypriots were compared to 46 other populations. The Greek Cypriot population in these analyses clustered with populations mainly from south Europe and Japan which have low E2 and E4 allele frequencies. The Greek Cypriot population will be studied further for elucidating the effect(s) and the role of APOE in cardiovascular disease and the APOE4 allele as a possible metabolic factor affecting the rate of expression of both Alzheimer's disease and vascular dementia.

Differential expression of cuticle-epidermis proteins in the shrimp Penaeus vannamei during molting

High-resolution mini-two-dimensional polyacrylamide gel electrophoresis (mini-2D-PAGE) was used to analyze silver-stained, soluble proteins from the cuticle-epidermis of Penaeus vannamei during molting. The 2D-PAGE patterns of epidermis polypeptides from metecdysis and anecdysis/proecdysis molt stages demonstrated similarities as well as several quantitative and qualitative differences. Quantitative modulation in polypeptide expression was noted in at least seven prevalent polypeptides during molting. A 50 kDa protein is specifically expressed in anecdysis/proecdysis tissue samples. Quantitative and qualitative differences were also noted in proteins migrating mainly in the molecular mass ranges of 26-32 kDa. An overall increase in polypeptide expression was noted in this molecular mass range at metecdysis as compared to anecdysis/proecdysis epidermis tissues. These results indicate modulation of cuticle-epidermis proteins in Penaeus vannamei shrimps during molting.