Clinical and genetic characterization of a cohort of proteinuric patients with biallelic CUBN variants.

BACKGROUND: Proteinuria is a well-known risk factor for progressive kidney impairment. Recently, C-terminal cubilin (CUBN) variants have been associated with isolated proteinuria without progression of kidney disease. METHODS: Genetic testing of 347 families with proteinuria of suspected monogenic cause was performed by next-generation sequencing of a custom-designed kidney disease gene panel. Families with CUBN biallelic proteinuria-causing variants were studied at the clinical, genetic, laboratory and pathologic levels. RESULTS: Twelve families (15 patients) bearing homozygous or compound heterozygous proteinuria-causing variants in the C-terminal CUBN gene were identified, representing 3.5% of the total cohort. We identified 14 different sequence variants, five of which were novel. The median age at diagnosis of proteinuria was 4 years (range 9 months to 44 years), and in most cases proteinuria was detected incidentally. Thirteen patients had moderate to severe proteinuria at diagnosis without nephrotic syndrome. These patients showed lack of response to angiotensin-converting enzyme inhibitor (ACEi) and angiotensin receptor blocker (ARB) treatment, normal kidney biopsy and preservation of normal kidney function over time. The two remaining patients presented a more severe phenotype, likely caused by associated comorbidities. CONCLUSIONS: Identification of C-terminal pathogenic CUBN variants is diagnostic of an entity characterized by glomerular proteinuria, normal kidney histology and lack of response to ACEi/ARB treatment. This study adds evidence and increases awareness about albuminuria caused by C-terminal variants in the CUBN gene, which is a benign condition usually diagnosed in childhood with preserved renal function until adulthood.

46,XX T testicular disorder of sex development. Case report.

OBJECTIVE: We present a case of X-Y translocation with male phenotype (46,XX testicular disorder of sex development) and review the literature. METHODS: Disorders of sex development with mismatch of genetic, gonadal and phenotypic sex are quite rare, and some are due to genetic or chromosomal abnormalities. The karyotype was investigated by a cytogenetic study of peripheral blood (phytohemagglutinin-timulated lymphocyte culture over 72 hours). G-banding analysis of 25 metaphases showed a 46,XX chromosome constitution (46 chromosomes with XX sexual composition). Fluorescence in situ hybridization (FISH) analysis with probes for X centromeres and the sex-determining region of the Y chromosome (SRY) (testis-determining factor gene) showed two X chromosomes. The analysis also showed the SRY signal in the telomeric region of the short arm of one of the chromosomes. RESULTS: In recent years, a number of other genes involved in disorders of sex development in animals and humans have also been identified. Genetic defects in the peptide hormone receptors, members of the steroid receptor superfamily, and other transcription factors, as well as any of a series of enzymes and cofactors involved in steroid biosynthesis can cause abnormal determination and differentiation. CONCLUSIONS: Although chromosomal abnormalities are rarely present in patients with apparently normal external genitalia, they should be considered in urology consultations by adolescents and adults, particularly in the investigation of gynecomastia or infertility.

46, XX testicular DSD. Aportación de un caso / 46, XX testicular disorder of sex development. Case report

OBJETIVO: Presentamos un caso de translocación entre cromosomas X e Y, con fenotipo masculino (46,XX testicular DSD) y revisamos la literatura.MÉTODOS: Los trastornos de la diferenciación sexual en los que no hay correspondencia entre los sexos genético, gonadal y fenotípico son relativamente infrecuentes, algunos son debidos a alteraciones genéticas o cromosómicas.Se efectuó estudio citogenético, realizando cariotipo en sangre periférica (cultivo de linfocitos de 72 horas de duración estimulados por fitohemaglutinina). Las 25 metafases analizadas con bandas G muestran una formula cromosómica de 46,XX (46 cromosomas con formula sexual XX). Tras realizar FISH (hibridación “in situ” fluorescente) con sondas para centrómero de X y región SRY(gen determinante de testículos) de Y, se observan dos cromosomas X, y en la región telomérica del brazo corto de uno de ellos la señal para SRY.RESULTADOS: En los últimos años se han identificado varios genes a parte del SRY, en animales y en humanos que intervienen en los trastornos de la diferenciación sexual. Los defectos genéticos en los receptores de las hormonas péptidicas, los miembros de la superfamilia de los receptores esteroideos y otros factores de transcripción, así como cualquiera de una serie de enzimas y cofactores que intervienen en la biosíntesis de los esteroides pueden inducir una determinación y una diferenciación anómala.CONCLUSIONES: Aunque son poco frecuentes las alteraciones cromosómicas con genitales externos aparentemente normales, hay que tenerlas en cuenta sobre todo en la consulta de urología de adolescentes y adultos, fundamentalmente en el estudio de ginecomastia o de infertilidad(AU)

OBJECTIVE: We present a case of X-Y translocation with male phenotype (46,XX testicular disorder of sex development) and review the literature.METHODS: Disorders of sex development with mismatch of genetic, gonadal and phenotypic sex are quite rare, and some are due to genetic or chromosomal abnormalities. The karyotype was investigated by a cytogenetic study of peripheral blood (phytohemagglutinin-stimulated lymphocyte culture over 72 hours). G-banding analysis of 25 metaphases showed a 46,XX chromosome constitution (46 chromosomes with XX sexual composition). Fluorescence in situ hybridization (FISH) analysis with probes for X centromeres and the sex-determining region of the Y chromosome (SRY) (testis-determining factor gene) showed two X chromosomes. The analysis also showed the SRY signal in the telomeric region of the short arm of one of the chromosomes.RESULTS: In recent years, a number of other genes involved in disorders of sex development in animals and humans have also been identified.Genetic defects in the peptide hormone receptors, members of the steroid receptor superfamily, and other transcription factors, as well as any of a series of enzymes and cofactors involved in steroid biosynthesis can cause abnormal determination and differentiation.CONCLUSIONS: Although chromosomal abnormalities are rarely present in patients with apparently normal external genitalia, they should be considered in urology consultations by adolescents and adults, particularly in the investigation of gynecomastia or infertility(AU)