RESUMEN
PALB2 loss-of-function variants play an important role in breast, pancreatic and possibly, ovarian and gastric cancer susceptibility. Their frequency can be influenced by founder effects, already described in some populations. Herein, we have assessed the possible founder effect of PALB2 c.2257C>T (p.Arg753*) truncating variant among Greek breast cancer patients, while investigating possible correlations with cancer diagnoses. Following a lead deriving from a background study of highly selected Greek breast cancer patients, a total of 2496 breast and 697 ovarian cancer patients were directly genotyped for the PALB2 c.2257C>T truncating variant. Consequently, haplotype analysis was conducted on identified carriers, using seven microsatellite markers. The prevalence of the PALB2 variant was 0.24% (6/2496) and 0.14% (1/697) among breast and ovarian cases, respectively. Family history seems to be an important factor for the variant identification, although not reaching statistical significance. Microsatellite analysis on 12 carriers revealed a common shared haplotype, spanning a chromosomal region of ~1.2 Mb; the variant was possibly introduced in the Greek population ~1600 years ago. The variant confers high breast cancer risk, as illustrated by comparison with publicly available control groups. Genetic testing for PALB2, especially for the Greek founder c.2257C>T truncating variant, should be seriously considered in Greek breast cancer cases, since such findings could assist appropriate clinical management for the patients and their families.
Asunto(s)
Alelos , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/genética , Proteína del Grupo de Complementación N de la Anemia de Fanconi/genética , Efecto Fundador , Mutación de Línea Germinal , Eliminación de Secuencia , Adulto , Anciano , Anciano de 80 o más Años , Sustitución de Aminoácidos , Neoplasias de la Mama/diagnóstico , Estudios de Casos y Controles , Análisis Mutacional de ADN , Femenino , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Genotipo , Grecia/epidemiología , Haplotipos , Síndrome de Cáncer de Mama y Ovario Hereditario/diagnóstico , Síndrome de Cáncer de Mama y Ovario Hereditario/epidemiología , Síndrome de Cáncer de Mama y Ovario Hereditario/genética , Humanos , Mutación con Pérdida de Función , Persona de Mediana Edad , Clasificación del Tumor , Estadificación de Neoplasias , Linaje , Medición de Riesgo , Factores de Riesgo , Adulto JovenRESUMEN
Tuberous sclerosis complex (TSC) is a rare autosomal dominant disorder causing benign tumors in the brain and other vital organs. The genes implicated in disease development are TSC1 and TSC2. Here, we have performed mutational analysis followed by a genotype-phenotype correlation study based on the clinical characteristics of the affected individuals. Twenty unrelated probands or families from Greece have been analyzed, of whom 13 had definite TSC, whereas another 7 had a possible TSC diagnosis. Using direct sequencing, we have identified pathogenic mutations in 13 patients/families (6 in TSC1 and 7 in TSC2), 5 of which were novel. The mutation identification rate for patients with definite TSC was 85%, but only 29% for the ones with a possible TSC diagnosis. Multiplex ligation-dependent probe amplification (MLPA) did not reveal any genomic rearrangements in TSC1 and TSC2 in the samples with no mutations identified. In general, TSC2 disease was more severe than TSC1, with more subependymal giant cell astrocytomas and angiomyolipomas, higher incidence of pharmacoresistant epileptic seizures, and more severe neuropsychiatric disorders. To our knowledge, this is the first comprehensive TSC1 and TSC2 mutational analysis carried out in TSC patients in Greece.