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Biomedical subjects

H Rivera

Publications and source records attributed to H Rivera.

176 records · Page 10Linked to original sources
PubMedDate not supplied

inv(9)(p24q13) in three sterile brothers.

Only nine non-polymorphic constitutional pericentric inversions of chromosome 9 have been described. We report on a familial inv(9)(p24q13) associated with sterility in three brothers. The mother's chromosomes were normal in blood lymphocytes (n=130); the father was already deceased and his karyotype unknown. However, the presence of any of the maternal chromosomes 9 (as assessed by C-banding) in her carrier children is inconsistent with the assumption of maternal mosaicism. Two single sisters were also carriers. The same rearranged chromosome 9 in the three sterile brothers can hardly be regarded as a fortuitous association, especially when the breakpoints are almost identical to those of the sole inversion previously found in an azoospermic male. If their father was a carrier, the observed sterility may be the result of 'chromosome anticipation', a phenomenon already invoked for certain familial chromosomal rearrangements.

Adult↗
PubMedDate not supplied

An intracranial carcinoma in a Mexican woman with Bloom syndrome.

An intracranial cell squamous carcinoma was found in a 27-year-old Mexican woman with Bloom syndrome (BS), including growth retardation, sun-sensitive telangiectatic erythema, defective immunity, and increased number of mitotic chiasmata and sister chromatid exchanges. The tumour, probably originating from the inner or middle ear epithelium, was resected but the patient died a few days after surgery. There was no parental consanguinity nor Jewish or European ancestry for at least five generations; in fact, her parents were mostly indigenous people. This case represents an undescribed intracranial malignancy in BS and the third Mexican BS patient reported. The typical BS phenotype in a woman with pigmented skin challenges the contention that pigmented females are less severely affected.

Adult↗
PubMedDate not supplied

Functional Xp disomy and hypomelanosis of Ito.

BACKGROUND: Hypomelanosis of Ito (HI) is a neurocutaneous phenotype that reflects different mosaicisms, including functional imbalances secondary to chromosome-X inactivation patterns in certain X;autosome translocation carriers. METHODS: We assessed X inactivation patterns by means of the human androgen receptor (HUMARA) assay and BrdU labeling in affected and unaffected skin of a young female with HI and a de novo t(X;13)(Xp13q;Xq13p). PCR analysis was carried out in DNA extracted from uncultured and cultured skin, whereas the BrdU replication patterns were sought in cultured fibroblasts. Parental DNA was also tested. Fluorescence in situ hybridization (FISH) with X and 13/21 centromere probes (DXZ2 and D13Z1/D21Z1) and a cosmid for the X inactivation center were also performed to refine breakpoint assignments. RESULTS: An X inactivation pattern implying functional Xpter-->q11 disomy was found in DNA extracted from uncultured hypopigmented skin, whereas preferential inactivation of the normal X was observed in uncultured normal skin as well as in cultured fibroblasts (after one passage) from both affected and unaffected skin areas. PCR analysis also showed paternal origin of the translocation. BrdU labeling of metaphases from hypopigmented and normal skin primary cultures showed der(Xq13p) to be inactive in about 25% of the cells. FISH revealed that der(Xp13q) had a compound centromere, whereas der(Xq13p) retained 13 centromere repeats but lacked X centromere sequences. Hence, breakpoints were assigned to Xq11 and 13q10. The X inactivation center cosmid gave a signal on both normal X and der(Xp13q), indicating that the inactivation center was not disrupted by the translocation. CONCLUSIONS: These findings confirm that mosaic functional Xp disomy, rather than disruption of X-linked genes, is associated with HI and involvement of the central nervous system (CNS) in some carriers of a structurally balanced X;autosome translocation.

Chromosomes, Human, Pair 13↗
PubMedDate not supplied

Neurofibromatosis type 1: a clinicopathological study of the orofacial manifestations in 6 pediatric patients.

Neurofibromatosis type 1 (NF1) is a relatively frequent mucocutaneous syndrome, which is transmitted as an autosomal dominant trait or which may represent neomutation. It is characterized by a variety of clinical manifestations, including multiple neurofibromas that are associated with a high risk of sarcomatous transformation. The aim of this report was to elucidate the orofacial manifestations observed in 6 pediatric patients (between 4 and 15 years of age) diagnosed with NF1. Physical, clinical, radiological, histological, and immunohistochemical studies were performed. Orofacial lesions were observed in all studied patients, located either in the soft tissues (4 cases) or centrally in the jaws (2 cases). All cases showed facial asymmetry, one of them exhibiting marked facial hemihypertrophy. All cases with soft tissue involvement were plexiform neurofibromas, while the intraosseous cases were diagnosed as solitary neurofibromas. Knowledge of the variability of presentation of orofacial soft tissue and bone manifestations of NF1 in children is necessary for prompt diagnosis.

Adolescent↗
PubMedDate not supplied

Incontinentia pigmenti: a case report.

Incontinentia pigmenti (IP) is a genodermatosis with an X-linked dominant mode of inheritance, characterized by ectodermal, mesodermal, neurological, ocular, and dental manifestations. The purpose of this case study was to report the oral and dental manifestations of an IP case in a Venezuelan pediatric patient. A 9 year-old Venezuelan girl was evaluated. She showed macular pigmented lesions in her face, trunk, back, legs, and fingers as well as abnormal hair distribution, alopecia on the vertex, and hypoplasia of eyebrows. During the dental examination, conical shaped-teeth and delayed dental eruption was evidenced. The microanalytical examination showed dentin without significant alterations in the mineralization except for hypermineralization in focal areas. In addition, a decrease in the enamel mineralization was observed.

Child↗
PubMedDate not supplied

[Amelogenesis imperfecta. Description of a clinical case].

A family of five was examined. Four of them presented with enamel alteration including changes in colour and loss of enamel surface. A genetic study was undertaken which revealed an autosomal dominant inheritance with complete penetration and variable expressivity. This is reflected in shape, number, extension and depth of the affected areas. Amelogénesis Imperfecta type IV was diagnosed using Shields classification.

Adolescent↗
PubMedDate not supplied

[Multidisciplinary focus on dentinogenesis imperfecta type II. Clinical analysis. Ultrastructural and genetic pathology].

A review of the more relevant clinical, radiological, histopathological and genetics aspects of Dentinogenesis imperfecta (DI) is presented, together with the description of a family with DI. The complete analysis of the affected and non-affected members showed that the defect can be classified as a DI type II with an autosomal dominant mode of inheritance with complete penetrance and variable expressivity. Also it is necessary to emphasize the importance of a multidisciplinary approach (Pedodontists, Oral Pathologists and geneticists) in the description, diagnosis and treatment of the individuals affected with DI.

Adult↗