Measuring impulsivity in Parkinson's disease: a correlational and structural neuroimaging study using different tests.

BACKGROUND AND PURPOSE: Impulsivity is an aspect of personality and a major component of multiple neuropsychiatric conditions. In Parkinson's disease, it has been associated with the expression of impulse control disorders, a highly prevalent non-motor complication. Even though multiple tests of impulsivity have been used in this context, the impact of test choice has not been addressed. The aim was to evaluate whether different impulsivity measures in Parkinson's disease share substantial inter-scale and anatomical correlations or rather mirror different underlying phenomena. METHODS: In a consecutive sample of 89 Parkinson's disease patients without impulse control disorders, four common tests were evaluated assessing different aspects of impulsivity: impulsiveness trait, decisions under implicit risk with and without losses, and delay discounting. Correlations among test scores were analysed and each score was used as a regressor in a set of grey matter volume (GMV) voxel-based morphometry analyses to explore their brain structural correlates. RESULTS: No significant correlations were found between the different impulsivity tests. Furthermore, their structural brain correlates were divergent. Impulsiveness trait appeared to be associated with lower GMV in dorsal-lateral prefrontal cortices, implicit risk (with losses) with higher GMV in the left nucleus accumbens and lower left insular GMV, implicit risk (without losses) with higher GMV in the left lingual gyrus and lower GMV in the gyri recti and delay discounting with higher GMV in the left nucleus accumbens. CONCLUSIONS: In Parkinson's disease, different impulsivity measures reflect very dissimilar behavioural and brain structural correlates. Our results suggest that parkinsonian impulsivity is not a unitary phenomenon but rather a heterogeneous entity.

Neurocardiovascular pathology in pre-manifest and early-stage Huntington's disease.

BACKGROUND AND PURPOSE: Cardiovascular events are a major cause of early death in the Huntington's disease (HD) population. Dysautonomia as well as deterioration of circadian rhythms can be detected early in the disease progression and can have profound effects on cardiac health. The aim of the present study was to determine if patients with HD and pre-manifest mutation carriers present a higher risk of cardiovascular disease than non-mutation-carrying controls. METHODS: This was a prospective, cross-sectional, multicentre study of 38 HD mutation carriers (23 pre-manifest and 15 early-stage patients) compared with 38 age- and gender-matched healthy controls. Clinical and epidemiological variables, including the main haematological vascular risk factors, were recorded. Ambulatory blood-pressure monitoring and carotid intima-media thickness (CIMT) measurement were performed to assess autonomic function and as target-organ damage markers. RESULTS: Most (63.2%) patients with HD (86.7% and 47.8%, respectively, of the early-stage and pre-manifest patients) were non-dippers compared with 23.7% of controls (P = 0.001). CIMT values were in the 75th percentile in 46.7% and 43.5%, respectively, of the early-stage and pre-manifest patients, whereas none of the controls presented pathological values (P = 0.001 and P = 0.006, respectively). Nocturnal non-dipping was significantly associated with CIMT values in patients (P = 0.002) but not in controls. CONCLUSIONS: These results suggest that higher cardiovascular risks and target-organ damage are present even in pre-manifest patients. Although larger studies are needed to confirm these findings, clinicians should consider these results in the cardiovascular management of patients with HD.

Sap fluxes from different parts of the rootzone modulate xylem ABA concentration during partial rootzone drying and re-wetting.

Previous studies with partial rootzone drying (PRD) irrigation demonstrated that alternating the wet and dry parts of the rootzone (PRD-Alternated) increased leaf xylem ABA concentration ([X-ABA]leaf) compared with maintaining the same wet and dry parts of the rootzone (PRD-Fixed). To determine the relative contributions of different parts of the rootzone to this ABA signal, [X-ABA]leaf of potted, split-root tomato (Solanum lycopersicum) plants was modelled by quantifying the proportional water uptake from different soil compartments, and [X-ABA]leaf responses to the entire pot soil-water content (θpot). Continuously measuring soil-moisture depletion by, or sap fluxes from, different parts of the root system revealed that water uptake rapidly declined (within hours) after withholding water from part of the rootzone, but was rapidly restored (within minutes) upon re-watering. Two hours after re-watering part of the rootzone, [X-ABA]leaf was equally well predicted according to θpot alone and by accounting for the proportional water uptake from different parts of the rootzone. Six hours after re-watering part of the rootzone, water uptake by roots in drying soil was minimal and, instead, occurred mainly from the newly irrigated part of the rootzone, thus [X-ABA]leaf was best predicted by accounting for the proportional water uptake from different parts of the rootzone. Contrary to previous results, alternating the wet and dry parts of the rootzone did not enhance [X-ABA]leaf compared with PRD-Fixed irrigation. Further work is required to establish whether altered root-to-shoot ABA signalling contributes to the improved yields of crops grown with alternate, rather than fixed, PRD.

Validation of the Spanish version of Addenbrooke's Cognitive Examination III for diagnosing dementia.

INTRODUCTION: Addenbrooke's Cognitive Examination is a screening test used to diagnose dementia. The third edition of this test (ACE-III) was recently developed. The aim of this study was to translate and validate the ACE-III in Spanish. METHODS: The ACE-III was translated and adapted to Spanish. It was then administered to a group of healthy subjects as well as a group of patients with different types of mild dementia treated in 2 hospitals in Spain. RESULTS: Internal reliability (Cronbach's alpha = 0.927), inter-rater reliability (intraclass correlation coefficient = 0.976) and test-retest reliability (kappa 0.995) were excellent. Age (r = -0.512) and education (r = 0.659) showed a significant correlation with total test scores. The diagnostic accuracy of ACE-III was higher than that of the Mini-Mental State Examination, particularly for the group with the highest educational level. Researchers obtained normative data and cut-off points for the diagnosis of dementia. CONCLUSIONS: The Spanish version of the ACE-III is a reliable and valid test for diagnosing dementia. Its diagnostic accuracy is high, especially in patients with a higher level of education.

Prevalence and prognostic meaning of interstitial lung abnormalities in remote CT scans of patients with interstitial lung disease treated with antifibrotic therapy.

OBJECTIVES: To describe the prevalence and characteristics of interstitial lung abnormalities (ILA) in CT scans performed prior to the initiation of antifibrotics in a series of patients with interstitial lung disease (ILD), and to identify characteristics apparent on early CT scans that could help to predict outcomes. METHODS: We conducted a retrospective observational study. The original cohort consisted of 101 patients diagnosed with ILD and treated with antifibrotics in a tertiary hospital. Patients were included if they had a thoracic CT scan performed at least one year before initiation of therapy. They were classified radiologically in three groups: without ILA, with radiological ILA and extensive abnormalities. ILA were classified as subpleural fibrotic, subpleural non-fibrotic and non-subpleural. The initial scan and the latest CT scan performed before treatment were read for assessing progression. The relationship between CT findings of fibrosis and the radiological progression rate and mortality were analyzed. RESULTS: We included 50 patients. Only 1 (2%) had a normal CT scan, 25 (50%) had extensive alterations and 24 (48%) had radiological criteria for ILA, a median of 98.2 months before initiation of antifibrotics, of them 18 (75%) had a subpleural fibrotic pattern. Significant bronchiectasis and obvious honeycombing in the lower zones were associated with shorter survival (p = 0.04). Obvious honeycombing in the lower zones was also significantly (p < 0.05) associated with a faster progression rate. CONCLUSIONS: Fibrotic ILAs are frequent in remote scans of patients with clinically relevant ILD, long before they require antifibrotics. Findings of traction bronchiectasis and honeycombing in the earliest scans, even in asymptomatic patients, are related to mortality and progression later on.

Plasma progranulin levels in cortical dementia phenotypes with asymmetric perisylvian atrophy.

BACKGROUND AND PURPOSE: Decreased plasma progranulin levels are a very specific marker for the diagnosis of frontotemporal lobar degeneration (FTLD) caused by mutations in the progranulin gene (GRN). A frequent neuroimaging pattern in this type of dementia is asymmetric cortical atrophy. The aim of this study was to screen for GRN-linked FTLD in cases with different cortical dementia phenotypes and asymmetric perisylvian atrophy. METHODS: Progranulin plasma levels were analyzed in a variety of FTLD phenotypes (n = 71), dementia of the Alzheimer type (DAT) (n = 22) and probable Lewy body dementia (n = 8), both latter groups presented with asymmetric perisylvian atrophy. A group of elderly controls (n = 29) and DAT cases with symmetric atrophy (n = 33) were also analyzed. The GRN gene was sequenced in cases with lower plasma levels. RESULTS: Four cases with clinical FTLD phenotypes and plasma levels below 70 ng/ml were found to carry different GRN mutations: M1?, C139R, a point mutation in the splice donor site of intron 3 (A89VfsX41), and a deletion in exon 9 (A303AfsX57), this latter one being a new mutation. Thirteen cases with levels between 72 and 85 ng/ml did not show pathogenic changes in the GRN gene. None of the cases with asymmetric atrophy and clinical phenotypes other than FTLD had GRN mutations. CONCLUSIONS: Asymmetric perisylvian atrophy is not likely to predict progranulin-linked FTLD unless it is associated with a consistent FTLD clinical phenotype.

Widespread Increased Diffusivity Reveals Early Cortical Degeneration in Huntington Disease.

BACKGROUND AND PURPOSE: Huntington disease is a devastating genetic neurodegenerative disorder for which no effective treatment is yet available. Although progressive striatal atrophy is its pathologic hallmark, concomitant cortical deterioration is assumed to occur, but it is poorly characterized. Our objective was to study the loss of cortical integrity and its association with clinical indicators throughout the course of the disease. MATERIALS AND METHODS: Using a cohort of 39 patients with Huntington disease and 25 controls with available MR imaging (T1WI and DTI), we compared cortical atrophy and intracortical diffusivity across disease stages. Intracortical diffusivity is a DTI-derived metric that has recently been suggested to detect incipient neuronal death because water can diffuse more freely in cortical regions with reduced neural density. RESULTS: We observed progressive thinning and increasing diffusivity within the cerebral cortex of patients with Huntington disease (P < .05, corrected for multiple comparisons). Most important, in the absence of pronounced atrophy, widespread increased diffusivity was already present in individuals with premanifest Huntington disease, correlating, in turn, with clinical and disease-specific progression markers. CONCLUSIONS: Intracortical diffusivity may be more sensitive than cortical thinning for tracking early neurodegeneration in Huntington disease. Moreover, our findings provide further evidence of an early cortical compromise in Huntington disease, which contributes to our understanding of its clinical phenotype and could have important therapeutic implications.

Deficit irrigation and rootstock: their effects on water relations, vegetative development, yield, fruit quality and mineral nutrition of Clemenules mandarin.

Differences between rootstocks, 'Cleopatra' mandarin and 'Carrizo' citrange, in soil-plant water relations and the influence of these factors on vigor, crop yield, fruit quality and mineral nutrition were evaluated in field-grown Clemenules mandarin trees irrigated at 100% of potential seasonal evaporation (ET(c)) (control treatment), or irrigated at 100% ET(c), except during Phases I and III of fruit growth and post-harvest when no irrigation was applied (deficit irrigation (DI) treatment), for 3 years. Differences between rootstocks in plant-soil water relations were the primary cause of differences among trees in vegetative development and fruit yield. After 3 years of DI treatment, trees on 'Cleopatra' showed more efficient soil water extraction than trees on 'Carrizo', and maintained a higher plant water status, a higher gas exchange rate during periods of water stress and achieved faster recovery in gas exchange following irrigation after water stress. The DI treatment reduced vegetative development more in trees on 'Carrizo' than in trees on 'Cleopatra'. Cumulative fruit yield decreased more in DI trees on 'Carrizo' (40%) than on 'Cleopatra' (27%). The yield component most affected by DI in 'Cleopatra' was the number of fruit, whereas in 'Carrizo' it depended on the severity of water stress reached in each phase (severe water stress in Phase I affected mainly the number of fruit, whereas it affected fruit size the most in Phase III). In the third year of DI treatment, water-use efficiency decreased sharply in trees on 'Carrizo' (70%) compared to trees on 'Cleopatra' (30%). Thus, trees on 'Cleopatra' were able to tolerate moderate water stress, whereas trees on 'Carrizo' were more sensitive to changes in soil water content.

Genetic analysis of incurvata mutants reveals three independent genetic operations at work in Arabidopsis leaf morphogenesis.

In an attempt to identify genes involved in the control of leaf morphogenesis, we have studied 13 Arabidopsis thaliana mutants with curled, involute leaves, a phenotype herein referred to as Incurvata (Icu), which were isolated by G. Röbbelen and belong to the Arabidopsis Information Service Form Mutants collection. The Icu phenotype was inherited as a single recessive trait in 10 mutants, with semidominance in 2 mutants and with complete dominance in the remaining 1. Complementation analyses indicated that the studied mutations correspond to five genes, representative alleles of which were mapped relative to polymorphic microsatellites. Although most double-mutant combinations displayed additivity of the Icu phenotypes, those of icu1 icu2 and icu3 icu4 double mutants were interpreted as synergistic, which suggests that the five genes studied represent three independent genetic operations that are at work for the leaf to acquire its final form at full expansion. We have shown that icu1 mutations are alleles of the Polycomb group gene CURLY LEAF (CLF) and that the leaf phenotype of the icu2 mutant is suppressed in an agamous background, as is known for clf mutants. In addition, we have tested by means of multiplex RT-PCR the transcription of several floral genes in Icu leaves. Ectopic expression of AGAMOUS and APETALA3 was observed in clf and icu2, but not in icu3, icu4, and icu5 mutants. Taken together, these results suggest that CLF and ICU2 play related roles, the latter being a candidate to belong to the Polycomb group of regulatory genes. We propose that, as flowers evolved, a new major class of genes, including CLF and ICU2, may have been recruited to prevent the expression of floral homeotic genes in the leaves.

[The knowledge, clinical control and attitudes of Primary Care physicians when dealing with epileptic patients. Preliminary findings]. / Conocimientos, control clínico y actitudes de los médicos de Atención Primaria frente a los pacientes epilépticos. Resultados previos.

INTRODUCTION: Epilepsy is a common disease with important social and economic repercussions. Patients with epilepsy have traditionally been discriminated by both the general population and physicians. A physician's lack of knowledge about epilepsy could be the cause of an incorrect clinical control (CC). AIMS: The purpose of this study is to examine the origins of the knowledge, the CC and the attitudes of physicians in Tenerife with respect to the treatment of patients with epilepsy. MATERIALS AND METHODS: In January 2003, all Primary Care physicians in Tenerife were given a questionnaire that asked them about their knowledge, CC and attitudes when dealing with cases of epilepsy. Of the 260 surveys initially sent out, 182 were returned. RESULTS: The questionnaire was answered by 70% of doctors, of which 34 were paediatricians and 148 were general practitioners, with no differences between sexes. Most physicians acquire their knowledge, observe and treat their first seizure in the Faculty and during their period of hospital residency. 44% of them are barely or not at all satisfied with their knowledge on the subject. The most highly valued therapists are neurologists and neuropaediatricians. The goal that is sought is to eliminate the impact of the disease on the patient's quality of life. They rarely establish or modify antiepileptic treatment and state that they have doubts about neuropsychological disorders and integrating patients with epilepsy in the workplace. CONCLUSIONS: The physicians in Tenerife define themselves as professionals with scant knowledge about epilepsy and feel they are poorly qualified to treat patients with the disease, who are usually referred to specialists in Neurology.

An arabinose-inducible expression vector, pAR3, compatible with ColE1-derived plasmids.

Arabinose-inducible genetic elements from the Salmonella typhimurium arabinose operon were inserted into pACYC184. The resultant plasmid, pAR3, is compatible with ColE1-derived plasmids and allows efficient expression of recombinant (re) genes upon induction with arabinose. These features make it convenient for use in combination with standard gene expression vectors for the independently controlled production of two or more re-polypeptides in Escherichia coli.

Different PrlA proteins increase the efficiency of periplasmic production of human interleukin-6 in Escherichia coli.

The export efficiency of a fusion of the Escherichia coli preOmpA signal peptide to human interleukin-6 can be significantly raised by coexpressing three different prlA alleles of sec Y along with wild type secE. The effect seems prlA-specific, as prlG1 (a prl allele of secE) does not affect the export of preOmpA-hIL-6. Coexpression of secD and secF also stimulates the export of the fusion protein.

Modified Anderson procedure for correcting abnormal mixed head position in nystagmus.

BACKGROUND/AIM: Treatment of nystagmus is controversial mainly in cases where it is combined with abnormal head position. This study was carried out to demonstrate that patients with abnormal head position in all three axes associated with nystagmus show improvement in the torsional and vertical components if only horizontal factors are addressed by surgical weakening of the horizontal muscles. METHODS: 21 patients with horizontal nystagmus and abnormal head position were studied. All had an abnormal head position in all three axes with a predominant head turn. In all cases a modified Anderson procedure was performed---that is, 2 mm retroequatorial recessions of the horizontal yoke rectus muscles responsible for the blockage position, plus corrective surgery for strabismus when needed. RESULTS: The three components of the abnormal head position were improved with surgery of horizontal yoke rectus muscles only (p=0.001). CONCLUSIONS: Large recessions of the horizontal yoke rectus muscles in nystagmus with blockage position, when the head turn predominates over the vertical and torsional components, are effective in diminishing the abnormal head position on all three axes.

[Evaluation of food intake in hemodialysis using a food consumption and appetite questionnaire]. / Valoración de la ingesta en hemodiálisis mediante un cuestionario de consumo alimentario y apetito.

Protein calorie malnutrition is a common complication in chronic hemodialysis patients (CHP). Although many factors could promote malnutrition, inadequate nutrient intake seems to be one of the most important. An Appetite and Diet Assessment Questionnaire (ADAQ) was developed, and we have performed a cross-sectional study in 44 CHP to investigate its capacity to predict an inadequate intake. Dietary evaluation was based on a diet diary-assisted recalls (DDAR). On the other hand, the validity of PCR and the differences in the DDAR and ADAQ between the days of dialysis and the days without dialysis were studied. The predictive value of inadequate intake of the ADAQ and the PCR were analysed with the ROC curve. The protein intake was 1.3 +/- 0.3 g/kg/day and the energy intake 29.2 +/- 0.6 kcal/kg/day. The average PCR was 1.14 +/- 0.3. The ROC curve to predict inadequate intake from the ADAQ shows an area under the curve of 0.84 for the protein intake and 0.73 for the energy intake. A cut-off ponit of 18 gives a sensitivity of 100% and a specificity of 44% for the detection of poor protein intake (< 1.2 g/kg/day) and of 74% and 56% for the detection of poor energy intake (< 30 kcal/kg/day). The ROC curve to predict inadequate protein intake from the PCR obtains an area under the curve of 0.81. The cut-off 1.06 gives the best sensitivity (100%) and specificity (64%) for the detection of insufficient protein intake. We did not find any significant difference in the DDAR or in the ADAQ between the days of dialysis and the days without dialysis. Despite the subjective interpretation, the relationship between ADAQ and protein-energy intakes analysed by DDAR was highly significant. The questionnaire is simple and can therefore be used as a screening rest to detect and correct alterations in the diet which could otherwise lead to malnutrition. The determination of PCR gives a good sensitivity and specificity for the detection of poor protein intake, although the results are modified in anabolic or catabolic states which can clinically go undetected. We do not register differences in diet between the days of dialysis and the days without dialysis.

[Renal colic and lithiasis in HIV(+)-patients treated with protease inhibitors]. / Cólico renal y litiasis en pacientes HIV (+) tratados con inhibidores de proteasas.

INTRODUCTION: Protease inhibitors, mainly Indinavir, are widely used drugs for the treatment of patients infected by the human immunodeficiency virus (HIV) and are related to renal colic and urinary obstruction. These conditions are the result of urine excretion of these drugs which favours the formation of small calculi (crystalluria and lithiasis). MATERIAL AND METHODS: Five PI treated HIV(+) patients; four males, one female, have recently been seen for renal colic at the Lithiasis Unit, Fundación Jiménez Díaz (FJD). All five patients had renal colic, one bilateral and one renal obstruction and fever. Small lithiasic concretions of null or minor radiological calcium density were identified by urinary X-ray and UIV. The patients had haematuria, crystalluria and urinary pH 5.0-6.0. Treatment was symptomatic, pharmacologic, emergency in situ extracorporeal shock-wave lithotrity (ESWL), or ureteral catheterisation, as appropriate. RESULTS: Patients had been treated with these antiviral agents for several months. They all required urologic care: pharmacologic, ureteral catheterisation, or ESWL, with good results. No stones were obtained for mineralogic analysis, but crystalluria was identified as being due to Indinavir and calcium oxalate. CONCLUSIONS: Renal excretion and urinary elimination of PIs (or their metabolites) results in asymptomatic crystalluria in HIV(+) patients treated with this class of drugs. Other cases present genuine calcium oxalate calculi with sings of renal colic and urinary obstruction requiring urologic care.

[Bladder hyporeflexia caused by vinca alkaloids]. / Hiporreflexia vesical producida por los alcaloides de la vinca.

Presentation of one case of hyporreflexic bladder like a first step of neurotoxicity due to Vinca alkaloids. These drugs produces peripheral neuropathies as usual, but in some rare occasions they may affect to the autonomic nervous system with its effects in the bladder producing hyporreflexic. This disease reverts spontaneously after suppressing drugs.

[Bone abnormalities. Muscular dystrophy and lithiasis: lithogenic factors and therapeutic difficulties]. / Deformidades esqueléticas. Distrofia muscular y litiasis: factores litogénicos y dificultades terapéuticas.

UNLABELLED: Duchenne's muscular dystrophy with kypho-scoliosis, progressive muscle weakness and abnormal fatigue of the muscles results in an immobilisation syndrome with increased bone resorption and hypercalciuria. The accompanying chest deformity alters the respiratory capacity, causing pulmonary insufficiency, acidosis and acid urine. Dorso-lumbar kypho-scoliosis, occasionally very serious, alters the status of the upper urinary tract affecting urine transportation (stasis). Thus, hypercalciuria, urinary acidosis, stasis and infection will determine the formation of urinary lithiasis that can take place in these patients. MATERIAL AND METHODS: 15 patients with a variety of myopathies (Duchenne's disease, Myasthenia gravis,...) or serious skeletal deformities with metabolic renal lithiasis (pyelic or calyceal) were seen by our group. Other patients presented post-traumatic (paraplegia, hemiplegia,...) or poliomyelitic skeletal sequels or Pott's disease, with septic lithiasis. After evaluating all likely approaches including ESWL, the latter was chosen being the least aggressive. Conventional surgery, either percutaneous or endoscopic, foretells technical problems in terms of lithiasis approach. Both the case introducing the subject, Duchenne's muscular dystrophy, with bilateral renal lithiasis and the others are a reflection of complexity of finding the righ approach for these patients, including ESWL. RESULTS: Scoliosis was not a technical obstacle, since patients could be placed in lateral/oblique position to situate the stone in the right spot for lithotrity. Debris removal was easy, with no obstructive complications, in spite of the significant immobilisation of these patients. CONCLUSION: Immobilisation syndrome, acidosis, stasis and infection could jointly determine the lithogenesis mechanism in patients with muscle diseases or serious skeletal deformities and with renal lithiasis. ESWL has an opportunity in serious cases, where other techniques including surgery have major difficulties.

Increasing the efficiency of protein export in Escherichia coli.

Export of recombinant proteins to the periplasm of Escherichia coli is in many cases preferable to cytoplasmic production. However, when the protein is overexpressed, export efficiency decreases significantly and some advantages of the system are lost. This is what happens when attempting to produce recombinant human interleukin-6 (hIL-6) as a pre(OmpA) fusion in E. coli. Assuming that the host protein export machinery becomes overloaded, we have tested the effect of providing the host with additional copies of two key components of that machinery. Supplementation with a plasmid bearing prlA4 (secY allele) and secE genes increased the ratio of mature to precursor hIL-6 from 1.2 to 10.8. The increase in processing ratio was associated with the accumulation of a larger amount of total (mature plus precursor forms) hIL-6. Providing a plasmid-borne wild-type prlA was ineffective compared to prlA4 allele. This suggests that the PrlA protein, a component of the translocator, recognizes features at the mature portion of secretory substrates independently of those at the signal peptide portion.

Discordant retinoblastoma in monozygotic twins due to deletion of 13q14.

PURPOSE: To report discordant retinoblastoma in monozygotic twins, confirmed by GeneScan. METHODS: One twin presented unilateral retinoblastoma that was treated with enucleation; the other twin had no retinoblastoma. To confirm monozygosity, DNA from leukocytes was analyzed through GeneScan with highly polymorphic markers; to exclude 13q14 deletion, FISH analysis was performed in leukocytes and oral cells of both twins and their parents and in retinal tissue of the affected twin with the cDNA LSI RB1 probe. RESULTS: GeneScan analysis confirmed monozygosity. 13q14 deletion was observed in homozygous state in retinal tissue and in heterozygous state in oral cells and leukocytes of the affected twin. The nonaffected twin and parents showed no deletion of 13q14. CONCLUSIONS: These data show unexpected differences in monozygotic twins that could be explained by postzygotic events in embryonic development.