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O Frota-Pessoa

Publications and source records attributed to O Frota-Pessoa.

At least 19 recordsLinked to original sources
PubMed2000

Calculation of recurrence risks for heterogeneous genetic disorders.

We present general formulae for several common situations in the genetic counseling of heterogeneous disorders. The occurrence or not of parental consanguinity is taken into account, since it distorts significantly the prior probabilities favoring the different mechanisms. Nonsyndromic deafness is used as a numerical application, since it can be produced by any type of monogenic inheritance and can be mixed with variable proportions of environmental cases. Recurrence risks are calculated including or not including environmental factors in the origin of the defect. In underdeveloped countries the proportion of environmentally determined cases of deafness is significantly higher than in first-world countries. Therefore, when environmental causes cannot be excluded, recurrence risks are always higher in developed than in developing countries. On average, when parental consanguinity is present there is a significant increase in recurrence risks for deafness, whether environmental factors are included or not.

Consanguinity↗
PubMed1995

Why is the reproductive performance lower in Becker (BMD) as compared to limb girdle (LGMD) muscular dystrophy male patients?

We had previously reported that patients affected with BMD have a significantly reduced reproductive performance (f = 0.12) as compared to male LGMD patients of similar age and physical impairment (f = 0.98). In the present study parameters such as the socio-economic level, as well as psychosocial, intellectual, and psychiatric functionings could not explain the low fitness of BMD patients. The effect of genetic counseling, a greater difficulty in coping with the disease, and relating to women and/or a potential malfunction of reproductive physiology are discussed as possible causes.

Adult↗
PubMed1995

Becker and limb-girdle muscular dystrophies: a psychiatric and intellectual level comparative study.

There are some indications that Becker muscular dystrophy (BMD) might be related to mental disorders and mental retardation (MR). To investigate this question, we made a standardized psychiatric and intellectual level assessment of 22 BMD patients in comparison with 22 limb-girdle muscular dystrophy (LGMD) patients. There were not significant differences between the two groups. Twelve patients (54.5%) in each group received at least one lifetime psychiatric diagnosis, the most frequent being depressive disorders. The intelligence quotient means for BMD was 85.9 and 87.8 for LGMD. There was one case of mild MR among BMD patients and two cases among LGMD patients.

Adult↗
PubMed1987

Phenotypic spectrum of 45,X/46,XY individuals.

We report on five patients with 45,X/46,XY mosaicism. In these subjects, as well as in 58 individuals from the literature with a similar chromosome constitution, we did not find a preponderance of 46,XY cells among patients showing ambiguous to abnormal male external genitalia when compared to those patients with slight or no virilization. However, the average frequency of 46,XY cells in blood in these mosaic individuals suggests that this sample includes mainly individuals whose mosaicism originated early in embryonic cell division. Those individuals whose mosaicism originated later are not significantly represented in this sample and would have higher frequencies of 46,XY cells. These individuals would be excluded from an intersex sample if they had well-virilized genitalia. This ascertainment bias suggests that the degree of virilization depends on the frequency of 46,XY cells.

Bone Marrow↗
PubMed1986

A Bayesian method for the estimation of penetrance: application to mandibulofacial and frontonasal dysostoses.

We describe a Bayesian method of estimating penetrance from genealogical data. It consists of calculating the likelihood of the data alone to make inferences about penetrance without sample space considerations. The method is applied to mandibulofacial dysostosis giving a penetrance of 0.908 with 0.95 credible interval of [0.809; 0.972] and to frontonasal dysostosis giving a penetrance of 0.670 with 0.95 credible interval of [0.457; 0.851].

Craniofacial Dysostosis↗
PubMed1986

Treatment of Duchenne muscular dystrophy with growth hormone inhibitors.

A controlled, double-blind therapeutic trial with the drug mazindol, a growth hormone inhibitor, was performed in a pair of 7 1/2 year-old monozygotic twins, with Duchenne muscular dystrophy (DMD). The rationale for this trial was based on a patient (reported previously) affected simultaneously with DMD and growth hormone (GH) deficiency, who is showing a benign course of the dystrophic process and is still walking at 18 years. One of the twins received 2 mg of mazindol daily, while the other received a placebo. The assessment, repeated every 2 months, included weight and height measurements, functional and motor ability tests, ergometry and determinations of serum enzymes and GH levels. After one year of trial the code was broken and it was seen that the twin under placebo treatment was strikingly worse than his brother, the progression of whose condition was practically arrested. These results strongly suggest that treatment with a GH inhibitor is beneficial for DMD patients.

Body Height↗
PubMed1984

Testicular regression in a patient with virilized female phenotype.

The 16-year old girl studied here had ambiguous external genitalia, ie, enlarged clitoris, pseudo vagina, and rudiments of Wolffian tubes. Her karyotype was 46,XY and she was H-Y antigen-positive. In spite of absence of gonadal tissue, genital virilization suggests presence of testes during embryogenesis. This patient is compared to 20 others with testicular regression from the literature. Autosomal-recessive inheritance of this condition is proposed.

Adolescent↗
PubMed1984

Late infantile autosomal recessive myotonia, mental retardation, and skeletal abnormalities: a new autosomal recessive syndrome.

Four sibs of non-consanguineous parents who had myotonia from late infancy are described. Mild to moderate mental retardation, severe bone abnormalities of the vertebral column (mainly in the thoracolumbar region), and short stature were also observed. Autosomal recessive inheritance is demonstrated. These cases are compared with reported cases of the Schwartz-Jampel syndrome.

Adolescent↗
PubMed1981

Autosomal dominant late adult spinal muscular atrophy, type Finkel.

We describe clinical and genetic data from the study of two families with 80 members affected with the autosomal dominant, slowly progressive spinal muscular atrophy of late onset (average 48.8 years), first described by Finkel in 1962. Electromyography and muscle biopsy of a number of patients confirmed the neurogenic nature of the conditions. Unusual findings in this disorder were cramps, spontaneous fits of suffocation, and symptomatic myotonia. Other manifestations are slow loss of muscle strength and progressive proximal atrophy, which starts in the lower limbs and progresses to the upper limbs; hypoactive or absent tendinous reflexes; and generalized fasciculations. Sensory and cranial nerve function is unimpaired. Probabilities for genetic counseling are evaluated by means of a method adequate to the late-onset nature of the condition.

Diagnosis, Differential↗
PubMed1980

H-Y antigen expression in a case of XX true hermaphroditism.

Cells from an XX true hermaphrodite expressed a reduced amount of H-Y antigen when compared with normal XY cells and with cells from his father, who had an XY/XX chromosomal constitution. His mother had a normal karyotype and was H-Y negative. The four brothers of the patient were clinically and karyotypically normal. An X-Y interchange followed by random inactivation of the X chromosome is proposed to explain the H-Y antigen titer found in the patient.

Child, Preschool↗
PubMed1980

Recurrence risks for Down syndrome.

The recurrence risks for Down syndrome due to an inherited translocation are estimated from empirical data in the literature for two maternal age groups: mothers under 30 and mothers 30 and over. These risks were found to be approximately 0.3% and 0.05%, respectively. The probability for two Down syndrome sibs both having an inherited translocation was estimated as about 18.2% for the former age group and 2.7% for the latter. The relative effectiveness in preventing. Down syndrome births by karyotyping affected children is discussed.

Chromosomes, Human↗
PubMed1979

H-Y gene expression in apparent absence of the long arm of the Y chromosome.

H-Y antigen expression was detected on cells from an individual having a presumptive 45,X/46,X,i(Yp) karyotype, but was absent on cells from another person having a 46,X,i(Yq) karyotype. This suggests that the short arm of the human Y chromosome is essential for H-Y antigen expression, at least in the subjects studied.

Chromosome Banding↗