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Horacio Rivera

Publications and source records attributed to Horacio Rivera.

8 recordsLinked to original sources
PubMed2005

Ambiguous genitalia by 9p deletion inherent to a dic(Y;9)(q12;p24).

We describe here a 3-month-old male infant with brachy-plagyocephaly, short neck, widely spaced nipples, mild hypertonia, and ambiguous external genitalia but with both testes in the scrotum and no Müllerian derivates. His karyotype was 45,X,der(Y;9)(q12;p24).ish der(Y;9)(DYZ3+,SRY+,9ptel-) de novo. This patient's impaired sex differentiation is consistent with gonadal dysgenesis and compares with the male-to-female sex reversal secondary to a partial 9p deletion in spite of an intact Yp or SRY locus documented in 24 patients including a sex-reversed girl with a (Y;9) dicentric derivative. As for the cytogenetic findings, this case represents the second instance of a de novo pseudodicentric (Y;9) chromosome with loss of both distal 9p and Yq12 regions, apparent intactness of SRY, and consistent or preferential inactivation of the Y centromere. In addition, the possible 9p23p-p22 duplication observed in this case evokes the concomitant 9p22-p21 duplication documented in the previous girl with a (Y;9) derivative. Hence, these striking similarities point to a nonrandom Y;9 rearrangement in patients with either sex reversal or gonadal dysgenesis. Even if the present pseudodicentric derivative had inactivated the Y centromere, the existence of some variant cells points to functional dicentricity as it has been documented in other Y;autosome dicentric derivatives.

Abnormalities, Multiple↗
PubMed2004

A t(1;9)(q23.3 approximately q25;q34) affecting the ABL1 gene in a biphenotypic leukemia.

Recurring chromosome translocations, which are found in leukemia, can result in the inappropriate expression of oncogenes or in the formation of chimeric genes that code for structurally and functionally abnormal proteins. The chromosomal t(1;9)(q23.3 approximately q25;q34) was found in a patient with biphenotypic leukemia. Fluorescence in situ hybridization (FISH) analysis revealed that the break on chromosome 9 occurred in the ABL1 gene. The breakpoint on chromosome 1 occurred distal to the PBX1 gene at 1q23.3, as shown by FISH using BAC RP11-503N16 and RP11-403P14, which flank the PBX1 locus; hence, the ABL1 gene can be fused with another gene distal to PBX1 gene.

Adolescent↗
PubMed2002

A 45,X sterile male with Yp disguised as 21p.

An azoospermic male was found to have, by means of banding techniques, a 45,X karyotype including a monocentric chromosome 21 with an euchromatic short arm that looked similar to Yp. This rearranged chromosome was further characterized by FISH with a whole Y chromosome paint and the alphoid repeats DYZ3 and D13Z1/D21Z1; the former probe gave a positive signal onto such a peculiar arm without spreading into the long arm, whereas the alphoid repeats revealed an apparent compound centromere with Y- and 21-sequences. Therefore, an unbalanced Y;21 whole arm translocation was concluded and the karyotype written as 45,X.ish der(Y;21)(p10;q10)(wcpY+,DYZ3+,D13Z1/D21Z1+). This patient represents the first case of a Y;21 translocation in an apparent 45,X male, constitutes the fifth instance of a 45,X sterile male, and conforms to previously established karyotype-phenotype correlations.

Adult↗
PubMedDate not supplied

del(X)(p22.1)/r(X)(p22.1q28) Dynamic mosaicism in a Turner syndrome patient.

We report on a 16-year-old patient with Turner syndrome who presented a mos 46,X,del(X)(p22.1)[35]/45,X [19]/46,X,r(X)(p22.1q28)[6]GTG-band karyotype. The R-banding showed that the abnormal X-chromosome was inactive in all 61 cells analyzed. Fluorescence in situ hybridization with a Xp/Yp subtelomeric probe revealed that both abnormal chromosomes lacked the complementary sequences, a fact consistent with a terminal deletion. Besides, the molecular analysis of the human androgen receptor gene showed that the rearranged chromosome was paternal in origin. Since the deleted and the ring chromosomes had the same size and banding pattern, and because the former was the predominant cell line, it was inferred that the Xp- formed a ring in some cells apparently without further loss of genetic material. However, the reverse sequence and even a simultaneous origin due to a complex intrachromosomal exchange are also conceivable. The mild Turner syndrome phenotype is explained by the mosaicism and by the size of the deleted segment.

Adolescent↗
PubMedDate not supplied

True vs. false inv(Y)(p11q11.2): a familial instance concurrent with trisomy 21.

A boy with Down syndrome due to a free trisomy 21 also had a metacentric Y chromosome with an arm euchromatic and the other heterochromatic inherited from his phenotypically normal father. This chromosome was mitotically stable and hybridized with the DYZ3 probe precisely at its primary constriction; in addition, a subtelomeric Xp/Yp probe gave the expected signal near the end of the euchromatic arm. So, the proband's karyotype was 47,X,inv(Y)(p11q11.2),+21. Given the high frequency of both chromosome anomalies, we regard its concurrence as a mere coincidence. This observation, along with previous reports, allows us to classify the apparent pericentric inversions of the Y chromosome into two types: "true" inversions characterized by an alphoid single centromere and mitotic stability, and "false" inversions in which a nonalphoid centromere has taken over the usual alphoid centromere; indeed, these chromosomes are dicentric and mitotically unstable. Finally, the inv(Y) polymorphism in man compares with that documented in other mammal species, in which the rearranged Y chromosome neither impairs the fertility nor has other phenotypical consequences.

Adult↗
PubMedDate not supplied

Pure partial trisomy 6p due to a familial insertion (16;6)(p12;p21.2p23).

There have only been eight patients with 6p pure trisomy involving different segments: four cases resulted from a translocation or insertion and four were due to an intrachromosomal duplication. We report here the first postnatally ascertained patient with a pure 6p partial trisomy due to an interchromosomal insertion (16;6)(p12;p21.2p23)mat. This rearrangement was confirmed by fluorescent in situ hybridization (FISH) with whole chromosome 6 and 16 painting probes. The clinical findings in the present patient were similar to those observed in previous cases, including craniofacial dysmorphism, minor anomalies, and lack of severe anatomical defects; yet, the unspecificity of many of these features prevented us from delineating the 6p pure trisomy syndrome.

Chromosomes, Human, Pair 16↗
PubMedDate not supplied

Topology of constitutional reciprocal translocations in metaphase.

We studied in 39 carriers of 26 reciprocal translocations (including five de novo and seven of indeterminate occurrence) the metaphase localization of the derivative chromosomes, their normal non-homologous counterparts (here called A and B), and two control pairs (C and D). In eight familial translocations, we analysed two to five carriers. We digitally captured 10 G-banded lymphocyte metaphases per individual and measured in microns the largest diameter (d) of the metaphase and six intercentromeric distances: (1) der A<-->der B (problem distance 1, pd1), (2) der A<-->B (pd2), (3) der B<-->A (pd3), (4) A<-->B (control distance 1, cd1), (5) the smaller distance between C and D (cd2) and (6) the largest distance between C and D (cd3); in addition, the average between C and D (cd4) was calculated. We used the formula Delta = 100(cd - pd)/d 12 times per metaphase, compared each pd vs. each cd, and tested the differences by the Wilcoxon matched-pair test. Although, in the whole sample there were not significant differences respect to cd1, this distance emerged as the proper control. In the eight familial translocations, the three pd vs. cd1 comparisons revealed that in 19/24 times the pd was smaller but only once reached significance (cd1 vs. pd2 in t[3;4]). In the analysis per individual the pd was smaller than cd1 in 19 (pd1), 22 (pd2) and 22 (pd3) cases although only twice reached significance. We conclude that in some translocations, the derivative chromosomes actually lie close from each other or from a normal non-homologous counterpart.

Chromosomes, Human↗