RESUMO

SHOX haploinsufficiency causes a wide spectrum of short stature phenotypes, such as Leri-Weill dyschondrosteosis (LWD) and disproportionate short stature (DSS). SHOX deletions are responsible for approximately two thirds of isolated haploinsufficiency; therefore, it is important to determine the most appropriate methodology for detection of gene deletion. In this study, three methodologies for the detection of SHOX deletions were compared: the fluorescence in situ hybridization (FISH), microsatellite analysis and multiplex ligation-dependent probe amplification (MLPA). Forty-four patients (8 LWD and 36 DSS) were analyzed. The cosmid LLNOYCO3'M'34F5 was used as a probe for the FISH analysis and microsatellite analysis were performed using three intragenic microsatellite markers. MLPA was performed using commercial kits. Twelve patients (8 LWD and 4 DSS) had deletions in SHOX area detected by MLPA and 2 patients generated discordant results with the other methodologies. In the first case, the deletion was not detected by FISH. In the second case, both FISH and microsatellite analyses were unable to identify the intragenic deletion. In conclusion, MLPA was more sensitive, less expensive and less laborious; therefore, it should be used as the initial molecular method for the detection of SHOX gene deletion.

Assuntos

RESUMO

The haplotypes of seven Y-chromosome STR loci (DYS19, DYS389I, DYS389II, DYS390, DYS391, DYS392, and DYS393) were determined in a sample of 634 healthy Brazilian males (190 adult individuals and 222 father-son pairs). The 412 adults were unrelated, and the 222 father-son pairs had their biological relationship confirmed using autosomal STRs (LR > 10,000). Among the 412 adults, a total of 264 different 7-loci haplotypes were identified, 210 of which were unique. The most frequent haplotype was detected in 31 instances, occurring with a frequency of 7.52 percent. The haplotype diversity index was calculated as 98.83 percent. Upon transmission of the 1,554 alleles, in 222 father-son pairs, six mutations were observed, with an average overall rate of 3.86 x 10-3 per locus. A haplotype with a duplicated DYS389I locus, and another with duplicated DYS389I, DYS389II, and DYS439 loci were detected in both fathers and their respective sons.

RESUMO

A síndrome de insensibilidade aos andrógenos é uma doença rara ligada ao X, causada por mutações no gene do receptor androgênico (AR), associada a uma variedade de fenótipos em indivíduos 46,XY. Avaliamos duas irmãs gêmeas de 23 anos com sexo social feminino encaminhadas por amenorréia primária, e que apresentavam gônadas palpáveis na região inguinal e cariótipo 46,XY. A ultra-sonografia pélvica não evidenciou útero. As dosagens basais revelaram concentrações elevadas de LH (35 e 42U/L), normais de FSH (7,9 e 7,8U/L) e altas de testosterona (1330 e 1660ng/dl). O estudo molecular identificou uma rara mutação missense no exon 5 do gene do AR com a troca de uma prolina por uma alanina na posição 766 da proteína. O aminoácido prolina 766 do AR é altamente conservado entre as espécies e situa-se em região correspondente ao domínio de ligação ao andrógeno.

Assuntos

RESUMO

Androgen insensitivity syndrome (AIS) is a rare X-linked disorder, caused by mutations in the androgen receptor gene (AR), associated with a variety of phenotypes in 46,XY individuals. We studied two 23 year-old twin-sisters with female social sex referred due to primary amenorrhea, who exhibited bilateral palpable gonads in the inguinal region and a 46,XY karyotype. The uterus was absent in pelvic sonograms. Basal LH levels were elevated (35 and 42 U/L), with normal FSH (7.9 and 7.8 U/L) and high testosterone levels (1330 and 1660 ng/dl). The molecular analysis identified a missense mutation in exon 5 of AR gene that changed a proline to an alanine at position 766 of the protein. Proline 766 is a highly conserved amino acid in the AR of several species and is located in the androgen binding domain.

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RESUMO

The currently used cutoff level for ACTH-stimulated 17- hydroxyprogesterone (17OHP) for the diagnosis of the nonclassical (NC) form of 21-hydroxylase deficiency (21OHD), established before molecular studies, is based on the mean + 2 SD of 17OHP levels of obligate heterozygotes. However, carriers of CYP21 mutations present variable ACTH-stimulated 17OHP levels, ranging from normal values up to 30 nmol/liter. The aim of this study was to determine whether ACTH-stimulated 17OHP levels in obligate carriers for 21OHD would be correlated with the impairment of the enzyme activity caused by these mutations, which would affect the 17OHP cutoff level for the diagnosis of the NC form. Fifty-nine parents of patients with the classical and NC forms of 21OHD had their DNA screened for the mutations found in the index case and were divided into three mutation groups according to the impairment of enzyme activity (A = 0%, B = 3%, and C > 20%). All parents carried mutations in one allele (29 of group A, 9 of group B, and 21 of group C). Blood samples were collected at baseline condition and 60 min after ACTH (250 microg i.v.) to measure 17OHP levels. The levels among groups A, B, and C were compared using the Kruskall Wallis test. ACTH-stimulated 17OHP levels identified 39% of the carriers (9 in group A, 2 in group B and 12 in group C). The mean +/- SD basal 17OHP levels in groups A, B, and C were: 2.94 +/- 1.89, 1.77 +/- 0.81 and 3.90 +/- 2.43 nmol/liter, respectively (P > 0.05) and for ACTH-stimulated levels were 12.6 +/- 7.2, 13.2 +/- 12.9 and 16.8 +/- 7.8 nmol/liter, respectively (P > 0.05). Two carriers presented ACTH-stimulated 17OHP levels between 30 and 45 nmol/liter and their entire CYP21 sequencing revealed only one mutation in heterozygous state indicating that the current cutoff level might overestimate the diagnosis of the NC form. We conclude that the variable ACTH-stimulated 17-OHP levels in carriers are not related to CYP21 gene mutations with different impairment of enzyme activity.

Assuntos