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Alkaptonuria is an inborn error of metabolism caused by deficiency of homogentisate 1,2-dioxygenase (HGD) which produces an excess of homogentisic acid (HGA). A case is presented of a 57 year old woman whose urine has turned black since birth. For 9 years she presented a greenish pigmentation in her nail beds that did not improve with antifungal treatments, and in the last 9 months she showed worsening large joint osteoarthritis. This situation forced her to use a wheelchair due to the intense pain caused by osteoarthritis in her hips and lumbar spine. From the description of symptoms, her urinary HGA was measured which confirmed the diagnosis of alkaptonuria. Analgesics and a diet without tyrosine-containing products were suggested. The patient was also referred for hip replacement surgery. This is the first reported case of alkaptonuria in Peru.

Supernumerary marker chromosomes (SMCs) without detectable alphoid DNA are predicted to have a neocentromere and have been referred to as mitotically stable neocentromere marker chromosomes (NMCs). Here we report the molecular cytogenetic characterization of a new case of Pallister-Killian syndrome (PKS) in a boy with an analphoid, inverted duplicated NMC derived from 12pter-->12p11.22 in his fibroblasts by using high-resolution comparative genetic hybridization (HR-CGH), multiplex fluorescent in situ hybridization (FISH) and bacterial artificial chromosome (BAC)-FISH mapping analyses with various alpha-satellite DNA probes, subtelomere probes and BAC-DNA probes. Precise identification of SMCs and NMCs is of essential importance in genetic counseling. HR-CGH is a more informative and often a faster way of precisely identifying the origin of SMCs. This case is the third report of PKS with an NMC containing an inverted duplication of partial 12p with available clinical data. These observations may help to determine the critical region for PKS and the mechanisms leading to the origin of the NMC derived from 12pter-->12p11.22 - a region that appears to be susceptible to the formation of neocentromeres. The use of subtelomeric probe PCP12p in buccal cells appears superior to the use of the centromere probe D12Z3 for the diagnosis of the PKS.

Aim: This study aims to assess the clinical features of 77 South American patients (73 Brazilian) with mucopolysaccharidosis type II (MPS II)., Methods: Details of the patients and their disease manifestations were obtained from a review of medical records, interviews with the patients and/or their families, and physical examination of the patients., Results: Mean birth weight was 3360 g, median age at onset of symptoms was 18 months and median age at diagnosis was 6 years. For the whole sample (median age, 8.2 years; range, 2.8-53.0 years), neurological degeneration, typical pebbly skin lesions, seizures and extensive dermal melanocytosis were found in 23.3, 13.0, 13.0 and 1.3% of the cases, respectively. The most frequently reported echocardiogram abnormality was mitral valve regurgitation. Refraction errors were the most common ophthalmological manifestation. The following characteristics were found to be associated with the severe form of MPS II: earlier age at biochemical diagnosis, higher levels of urinary glycosaminoglycans, language development delay, behavioural disturbances, poor school performance and mental retardation., Conclusion: Our results suggest that there is a considerable delay between the onset of signs and symptoms and the diagnosis of MPS II in Brazil (and probably in South America as well), and that many complications of this disease are underdiagnosed and undertreated. Therefore, the implementation of programmes aiming to increase the awareness of the disease, the availability of biochemical diagnostic tests and the provision of better support to affected patients is urgently needed.

Supernumerary marker chromosomes (SMCs) without detectable alphoid DNA are predicted to have a neocentromere and have been referred to as mitotically stable neocentromere marker chromosomes (NMCs). We report the molecular cytogenetic characterization of a new case with analphoid NMC derived from 15q25-->qter using high-resolution comparative genomic hybridization (HR-CGH) and multiplex fluorescence in situ hybridization analyses with various alpha-satellite DNA probes, all-human-centromere probe (AHC), whole chromosome painting probes, and a subtelomere probe. The propositus is a dysmorphic infant who, at age 3 months, showed accelerated growth, partial deafness, and a phenotype similar to that of the eight previously reported cases of distal 15q tetrasomy. Chromosome studies showed that he had a de novo extra SMC in 80% of cells examined. HR-CGH revealed rev ish enh(15)(q25qter). Molecular cytogenetic analysis and molecular DNA polymorphism study demonstrated that this extra SMC is an NMC containing an inverted duplication of the distal long arm of chromosome 15 (tetrasomy 15q25-->qter) which originated paternally, i.e. ish der(15)(qte-->q25::q25[neocen]-->qter)(AHC-, CEP15-, WCP15+, PCP15q++). This case further elucidates the phenotype related to tetrasomy of this specific chromosome segment and represents a new report of a neocentromere on distal chromosome 15q suggesting that this region appears to be susceptible to the formation of neocentromeres.

Although the effect of maternal age as a risk factor for Down syndrome (DS) is well known, the role of paternal age in the cause of DS has not been clearly established. To investigate this phenomenon we conducted a case-control study between July 1989 and February 1990. The cases were 318 children and teenagers with DS studied at the Specialized Educational Institutions of Lima City, Perú. They were paired with 1,196 control individuals that were selected from the birth records of 2 general hospitals of the city. For each case we tried to obtain 4 controls, paired by their date of birth, sex, and maternal age. The means of paternal age in the 2 groups were compared, first globally and then by groups of maternal age (< 21 years, 21-29 years, 30-34 years, 35-39 years and > 39 years). None of the comparisons gave a statistically significant difference between the 2 groups, using either the Student t-test or the Mann-Whitney U-test. The results obtained in this study give no evidence that paternal age can be considered a risk factor for the conception of a child with DS.

We report on an infant with multiple congenital anomalies and mosaic trisomy 8 [corrected]. Clinical findings are presented, and compared with those of the 24 cases previously reported. Some unusual characteristics found in this patient include macrocephaly, an extreme degree of palatal hypoplasia, and abnormally shaped long bones.

The aim of this work is to reevaluate the hypothesis of the existence of a possible genetic control of nondisjunction of chromosome 21. The population under study was the families trisomy (TLI) as diagnosed in the Medical Genetic Unit of LUZ from 1971 to 1988. The control population was the families of 418 individuals with no apparent genetic pathology (CON), approximately matched in age with the patients. The frequency of consanguineous unions in parents (UCPM), maternal grandparents (UCAM) and paternal grandparents (UCAP) of both patients and controls was determined. The results indicated that UCPM was significantly greater in TLI than CON while the UCAM and UCAP were more frequent in CON. The coefficient of consanguinity in parents of TLI was three times greater than in parents of CON. The results of this investigation suggest that the consanguinity should be considered another risk factor for the nondisjunction of chromosome 21 and it is independent of maternal age and support the hypothesis that there exists an autosomal recessive gene that, in the homologous state, results in a predisposition toward nondisjunction of chromosome 21 in the first mitotic division.

We describe a girl with multiple congenital abnormalities and developmental delay; her karyotype showed an apparently balanced translocation between the short arm of chromosome 1 and the long arm of chromosome 11, and an interstitial deletion of the long arm of chromosome 5 (q15q31). The clinical findings are compared with those described in other cases of 5q deletion, and the origin of the chromosome rearrangements is briefly discussed.

We report a boy with a de novo terminal deletion of chromosome 4q, (q31----qter) and compare him to 17 previously reported cases with the same anomaly. This case contributes further to the delineation of the del(4)(q31) phenotype, which seems to be clinically recognizable.