Biomedical subjects
Publications and source records attributed to H Rivera.
A 24-year-old female with a Swyer syndrome phenotype was found to have a 46,X,del (Y) (p11) karyotype. This observation is consistent with the recently confirmed assignment of the testis-determining master gene to the deletion interval 1A of the Y (Page et al., 1987). Otherwise, it illustrates the etiological heterogeneity of the Swyer phenotype and allows to emphasize the de novo origin of XYp-females.
A familial inv(4)(p16q21) ascertained through a woman who had a thanatophoric dwarf daughter and two abortions is presented. She and 23 other relatives were carriers, but no recombinants were found. The proportion of abortions and neonatal deaths in carriers' offspring was similar to that in non-carriers. A random segregation of the inverted chromosome was observed. The analysis of the present and previous familial chromosome 4 pericentric inversions indicates that: the breakpoint in q, with a limit between q21 and q25 determines the occurrence of inherited unbalances, and most recombinant chromosomes have duplication of the larger distal segment.
A 5-month-old girl had a typical 12p trisomy syndrome due to a monocentric i(12p) present in a 46-chromosome complement that also included the translocation of all 12q onto the 8p telomere; i.e., her complex karyotype could be written as 46,XX,-8,-12, +der(8),t(8;12)(p23.3;cen),+i(12p). The present concurrence of a whole-arm q translocation and an i(p) for a single chromosome, along with six previous similar instances involving chromosomes 4, 5 and 9, suggests the following origin for such a special rearrangement: a centric fission in G1 initially yielding two telocentrics; at the next replication, the tel(q) translocates onto a nonhomologous telomere (centromere-telomere fusion), whereas the tel(p) becomes an i(p). This mechanism can be either meiotic or postzygotic and surmises that the translocated long arm retains a partial centromere, which subsequently is inactivated and loses its staining properties.
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Sera from 3,369 sheep and 1,394 goats in Peru were examined by agar-gel immunodiffusion for antibodies to ovine progressive pneumonia virus (OPPV). The point prevalence rates for antibodies to OPPV in sheep were 1.7% to 40.6% (mean, 19.02%) in the 7 flocks studied, whereas for goats, the point prevalence rates for antibodies that cross-reacted with OPPV in 12 herds were 0.0% to 45.1%. For sheep, a direct association between increasing age and increasing seroreactivity to OPPV was established, and there was evidence to indicate that lambs born to primiparous ewes and raised separated from all other sheep after they were weaned may have been less likely to become infected with OPPV than those lambs born to multiparous ewes and not separated from other sheep after they were weaned. For goats, antibodies to OPPV were detected in 7 of 12 herds studied, the highest infection rate being present within a herd in the Lima department (district).
A 4-month-old male infant with muscular hypotonia, growth and psychomotor retardation, large low-set ears, hypoplastic genitalia, right hip luxation and bilateral equinovarus, was found to have a constitutional 46,XY,del(5)(q23.3q31.1) karyotype. From the comparison with 12 similar cases, a rather characteristic clinical phenotype emerges.
A 10-month-old girl with monosomy due to a de novo 45,XX,-15,-18,+tdic(15;18)(p11;p11) karyotype is described. The abnormal chromosome underwent dissociation into two telocentrics in 5/200 (2.5%) metaphases. This and other comparable instances indicate that, in addition to criss-cross separation of the dicentric chromatids, the characteristics of the anomalous reunion also influence the rate of dissociation. Besides, the mean maternal (31.2) and paternal (35.1) ages in this subtype of 18p monosomy are significantly increased.
A 17-year-old female patient with gonadal dysgenesis but no other turnerian features was found to have a 46,X,idic(X)(pter----q2803:q2803----pter) karyotype in her lymphocytes. Replication of the rearranged X was consistently late and symmetrical. It is postulated that the ovarian dysgenesis usually seen in nonmosaic carriers of Xq;Xq terminal rearrangements may be secondary to a nonreactivation of the abnormal chromosome before meiosis.
A constitutional chromosomal aberration was diagnosed in 38/163 (23.3%) azoospermic patients. Whereas the 47,XXY complement was the commonest (31/38 cases), the following abnormal karyotypes were also found: 46,XX; 46,X,del(Y) (q11); 46,X,r(Y); 46,XY,inv(1) (p3500q21.3)mat; and 46,Y,t(X;3) (q26;q13.2)mat (both the deleted and the annular Y were observed twice). Pooled data from the literature showed that the frequency of chromosomal abnormalities is higher in azoospermic (150.4/1000) than in infertile (55.3/1000) males, which in turn is higher than in newborns (less than 6/1000). The observed different frequency between azoospermic and infertile individuals is given by several types of chromosomal abnormalities, mainly by the complement 47,XXY. The analysis also showed that the male infertility secondary to rob translocations and supernumerary marker chromosomes is usually not related to azoospermia. The contrary occurs in certain rcp and gonosome;autosome translocations and in autosome inversions.
Two girls with the trisomy 3q2 clinical syndrome are presented. Their fathers were twins and carried a t(3;8)(q25;p23). Case 1, aged 8 months, had a 46,XX,der(8) complement. Case 2, died at 5 months of age before cytogenetic study, was considered to have the same karyotype. Both cases combined showed the majority of phenotypical features of trisomy 3q2 syndrome, including facial appearance, glaucoma, and visceral malformations. This observation suggests that the trisomy 3q25----qter is sufficient to produce the syndrome which shows variable expression in these cases.
A 4 1/2 years old boy was found to have hypoplasia of the pectoralis major right muscle and a karyotype 46,XY,inv(5)(p13q13)mat. This inversion, probably independent of the boy's malformation, was present in at least four generations and it seems neither to impair fertility nor to yield viable recombinants.
Sera from more than 100 alpacas (Lama pacos) from the Peruvian southern sierra were examined for antibodies to 8 viruses known to infect other domestic animals. On the basis of these serologic findings and previously published serologic or clinical data, it is now known that the alpaca can be infected with the following viruses: parainfluenza-3, bovine respiratory syncytial virus, bovine herpesvirus-1, bluetongue virus, border disease virus, influenza A virus, rotavirus, rabies virus, vesicular stomatitis virus, foot-and-mouth disease virus, and contagious ecthyma virus.
A 19-year-old female patient with gonadal dysgenesis and a de novo t(X;17) (Xp17q;Xq17p) is described. Since the critical segment Xq13----q26 was intact, this case is a further exception to the critical region hypothesis.
A 7 7/12-year-old girl with a de novo deletion 4p15.32----pter without the typical Wolf-Hirschhorn syndrome (WHS) is presented. This observation and others from medical literature suggest that monosomy 4p15.31----4p15.32, rather than 4p16, is the cause of the typical WHS.
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A 4 year-old boy was found to have a typical 7p2 monosomy syndrome, including craniosynostosis, due to a de novo del(7)(pter----p21.2::p15.2----qter). It is concluded that the band 7p21 (probably only the subband p21.1) is the critical segment for the full clinical expression of this aneusomy.
A 3-year-old girl with Bloom syndrome is described. She exhibited stunted growth of prenatal onset and defective immunity, but the typical skin manifestations were absent. Cytogenetic analysis revealed a 46,XX complement, 12.2% of metaphases with at least a structural aberration, and a ten-fold increase in the sister-chromatid exchange rate. Leukocyte beta-glucuronidase activity was reduced to about 1/3; the significance of this finding is not clear. The present observation demonstrates the variable expression of the disorder probably depending on ethnic and constitutional factors.
An eight-month-old girl with a de novo del(6)(q25) is described. She and other previous cases of 6q deletion showed concordance for developmental retardation associated with multiple unspecific congenital abnormalities, which do not yet allow the delineation of a syndrome. However, bilateral macular degeneration was found in the proposita and had been observed in another similar case, so it probably represents a distinctive feature of 6q terminal monosomy. This observation also suggests the existence of a dominant macular degeneration locus within 6q25----qter.