Analysis of FOXG1 Is Highly Recommended in Male and Female Patients with Rett Syndrome

We screened a cohort of 5 male and 20 female patients with a Rett spectrum disorder for mutations in the coding region of FOXG1, previously shown to cause the congenital variant of Rett syndrome. Two de novo mutations were identified. The first was a novel missense mutation, p.Ala193Thr (c.577G>A), in a male patient with congenital Rett syndrome, and the second was the p.Glu154GlyfsX301 (c.460dupG) truncating mutation in a female with classical Rett syndrome, a mutation that was previously reported in an independent patient. The overall rate of FOXG1 mutations in our cohort is 8%. Our findings stress the importance of FOXG1 analysis in male patients with Rett syndrome and in female patients when mutations in the MECP2 and CDKL5 genes have been excluded.

Scanning gate imaging of quantum dots in 1D ultra-thin InAs/InP nanowires

We use a scanning gate microscope (SGM) to characterize one-dimensional ultra-thin (diameter ≈ 30 nm) InAs/InP heterostructure nanowires containing a nominally 300 nm long InAs quantum dot defined by two InP tunnel barriers. Measurements of Coulomb blockade conductance versus backgate voltage with no tip present are difficult to decipher. Using the SGM tip as a charged movable gate, we are able to identify three quantum dots along the nanowire: the grown-in quantum dot and an additional quantum dot near each metal lead. The SGM conductance images are used to disentangle information about individual quantum dots and then to characterize each quantum dot using spatially resolved energy-level spectroscopy.

Gate-induced fermi level tuning in InP nanowires at efficiency close to the thermal limit

As downscaling of semiconductor devices continues, one or a few randomly placed dopants may dominate the characteristics. Furthermore, due to the large surface-to-volume ratio of one-dimensional devices, the position of the Fermi level is often determined primarily by surface pinning, regardless of doping level. In this work, we investigate the possibility of tuning the Fermi level dynamically with wrap-around gates, instead of statically setting it using the impurity concentration. This is done using Ω-gated metal-oxide-semiconductor field-effect transistors with HfO(2)-capped InP nanowires as channel material. It is found that induced n-type devices exhibit an optimal inverse subthreshold slope of 68 mV/decade. By adjusting the growth and process parameters, it is possible to produce ambipolar devices, in which the Fermi level can be tuned across the entire band gap, making it possible to induce both n-type and p-type conduction.

Sensitivity and specificity of a whole-blood RNA transcript-based diagnostic test for the diagnosis of prostate cancer (CaP) compared with prostate-specific antigen (PSA) alone

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Background: Screening for CaP with PSA testing is limited by a high number of false postives, particularly in the setting of benign prostatic hypertrophy (BPH). The goal of this study was to develop whole blood RNA transcript-based diagnostic tests that improve the diagnosis of CaP over PSA alone. Methods: From August 2006 to October 2008, three prospective cohorts of men consented to the collection of whole blood in PAXgene Blood RNA tubes for gene expression analysis: men with newly diagnosed, localized, untreated CaP, otherwise healthy men without CaP, and otherwise healthy men with BPH. 168 inflammation and CaP-related genes (Source MDx Precision Profiles) were assayed using optimized Q-PCR technology. Logistic regression methods were used to develop models to optimize prostate cancer diagnosis. Results: 182 men underwent expression analysis (n = 76, 76 and 30 for CaP, normal, and BPH cohorts, respectively). The CaP and normal cohorts were age matched (median age 60 yrs); the BPH cohort median age was 70. Considering only the CaP and normal cohorts, PSA alone (using a cut-off of 4 ng/ml) had a specificity of 94.7%, but sensitivity of only 71.1% for diagnosis of CaP, or 90.8% and 77.6%, respectively, when using age-adjusted PSA criteria. A model consisting of the expression analysis of 6 genes and PSA had a higher specificity (96.1%) and a much improved sensitivity (97.4%) for CaP diagnosis. When the BPH cohort was added, the improvement of the 6-gene model remained (sensitivity and specificity of 97.4% and 92.0% vs 77.6% and 88.1% using the age-adjusted PSA criteria). Further model development using the CaP and BPH cohorts yielded a 5-gene model which, integrated with PSA and age, correctly predicted 96.1% of the CaP pts and 93.3% of BPH pts. Conclusions: These results suggest that specific whole blood RNA transcript levels can assess abnormal gene expression associated with CaP. Such a molecular CaP biomarker would be a powerful tool to reduce unnecessary biopsies in patients without CaP and detect CaP in patients with PSA values below the current cutoff. Validation of these results is ongoing and will be available at the time of the meeting.

[Table: see text]

An optimized DHPLC protocol for molecular testing of the EXT1 and EXT2 genes in hereditary multiple osteochondromas

Hereditary multiple osteochondromas (MO) is an autosomal dominant bone disorder characterized by the presence of bony outgrowths (osteochondromas or exostoses) on the long bones. MO is caused by mutations in the EXT1 or EXT2 genes, which encode glycosyltransferases implicated in heparan sulfate biosynthesis. Standard mutation analysis performed by sequencing analysis of all coding exons of the EXT1 and EXT2 genes reveals a mutation in approximately 80% of the MO patients. We have now optimized and validated a denaturing high-performance liquid chromatography (DHPLC)-based protocol for screening of all EXT1- and EXT2-coding exons in a set of 49 MO patients with an EXT1 or EXT2 mutation. Under the optimized DHPLC conditions, all mutations were detected. These include 20 previously described mutations and 29 new mutations - 20 new EXT1 and nine new EXT2 mutations. The protocol described here, therefore, provides a sensitive and cost-sparing alternative for direct sequencing analysis of the MO-causing genes.

Multiplex ligation-dependent probe amplification to detect subtelomeric rearrangements in routine diagnostics

Subtelomeric rearrangements are believed to be responsible for 5-7% of idiopathic mental retardation cases. Due to the relative complexity and high cost of the screening methods used till now, only preselected patient populations including mostly the more severely affected cases have been screened. Recently, multiplex ligation-dependent probe amplification (MLPA) has been adapted for use in subtelomeric screening, and we have incorporated this technique into routine diagnostics of our laboratory. Since the evaluation of MLPA as a screening method, we tested 275 unselected patients with idiopathic mental retardation and detected 12 possible subtelomeric aberrations: a der(11)t(11;20)(qter;qter), a 19pter duplication, a der(18)t(18;10)(qter; pter), a 15qter deletion, a 8pter deletion, a 6qter deletion, a der(X)t(X;1)(pter;qter), a der(X)t(X;3)(pter;pter), a 5qter duplication, a 3pter deletion, and two 3qter duplications. The patients can be subdivided into two groups: the first containing de novo rearrangements that are likely related to the clinical presentation of the patient and the second including aberrations also present in one of the parents that may or may not be causative of the mental retardation. In our patient cohort, five (1.8%) subtelomeric rearrangements were de novo, three (1.1%) rearrangements were familial and suggestively disease causing, and four (1.5%) were possible polymorphisms. This high frequency of subtelomeric abnormalities detected in an unselected population warrants further investigation about the feasibility of routine screening for subtelomeric aberrations in mentally retarded patients.

Absence of constitutional Y chromosome AZF deletions in patients with testicular germ cell tumors

OBJECTIVES

To investigate the frequency of azoospermia factor (AZF) deletions in Dutch patients with testicular germ cell tumors (TGCTs). Reduced fertility is associated with TGCTs and reduced fertility and TGCTs might share genetic risk factors according to the testicular dysgenesis hypothesis. Up to 8% of infertility and reduced fertility in the general male population can be explained by the presence of constitutional deletions of part of the long arm of the Y chromosome (Yq11), referred to as the AZF region.

METHODS

In 112 patients with TGCT, screening for constitutional deletions in the AZF region was performed by multiplex polymerase chain reaction analysis in DNA extracted from peripheral blood lymphocytes. A set of 24 primer pairs, of which 20 primer pairs are homologous to previously identified and mapped sequenced tag sites within the AZF region were used.

RESULTS

No deletions in the Yq11 region were detected in any of the 112 patients.

CONCLUSIONS

Large Y chromosome microdeletions in the AZF region are not a major contributor to the development of TGCT and TGCT-associated reduced fertility.

A Psychometric Analysis of the Maslach Burnout Inventory-General Survey in the South African Police Service

The objectives of this study, which was undertaken by two members of the WorkWell Research Unit, were to validate the Maslach Burnout Inventory-General Survey (MBI-GS) for the South African Police Service and to determine the construct equivalence of this Inventory and bias for different race groups. A cross-sectional survey design was used. Stratified random samples ( N=2396) were taken of police members from nine provinces in South Africa. The study was based on the MBI-GS and a biographical questionnaire. Structural equation modelling confirmed a 3-factor model of burnout, consisting of Exhaustion, Cynicism and Professional Efficacy. All three factors showed acceptable internal consistencies. An exploratory factor analysis with target rotations confirmed the construct equivalence of the three factors for different race groups in the SAPS. No evidence was found for uniform or non-uniform bias of the items of the MBI-GS for different race groups.

A psychometric analysis of the Utrecht Work Engagement Scale in the South African police service

The objectives of this research were to validate the Utrecht Work Engagement Scale (UWES) for the South African Police Service (SAPS) and to determine its construct equivalence and bias in different race groups. A cross-sectional survey design was used. Stratified random samples (N = 2396) were taken of police members of nine provinces in South Africa. The UWES and a biographical questionnaire were administered. Structural equation modelling confirmed a 3-factor model of work engagement, consisting of Vigour, Dedication and Absorption. These three factors have acceptable internal consistencies. Exploratory factor analysis with target rotations showed equivalence of the three factors for different race groups in the SAPS. No evidence was found for uniform or non-uniform bias of the items of the UWES for different race groups. Opsomming Die doelstellings van hierdie navorsing was om die Utrecht- werksbegeesteringskaal (UWES) te valideer vir die Suid- Afrikaanse Polisiediens (SAPD) en die konstrukekwivalensie daarvan vir verskillende rassegroepe te bepaal. ’n Dwarssnee opname-ontwerp is gebruik. Gestratifiseerde ewekansige steekproewe (N = 2396) is van polisielede uit nege provinsies geneem. Die UWES en ’n biografiese vraelys is afgeneem. Strukturele vergelykingsmodellering het ’n 3-faktormodel, bestaande uit Energie, Toewyding en Absorpsie, aangetoon. Hierdie drie faktore het aanvaarbare interne konsekwentheid getoon. Eksploratiewe faktoranalise met teikenrotasies het konstrukekwivalensie vir die drie faktore vir verskillende rassegroepe in die SAPD getoon. Bewyse is nie gevind vir uniforme of nie-uniforme sydigheid van die items van die UWES vir verskillende rassegroepe nie.

Coping, stress and burnout in the South African police service in Kwazulu-natal

The objective of this research was to determine the relationship between coping, stress and burnout in the South African Police Service. A survey design was used. The study population (N = 257) consisted of police personnel in Kwazulu-Natal. The COPE, Police Stress Inventory and Maslach Burnout Inventory – General Survey (MBI-GS), were used as measuring instruments. Structural equation analysis showed that job demands (as stressors) are associated with exhaustion. Passive coping strategies contributed to exhaustion and cynicism, while seeking emotional support led to lower exhaustion. Exhaustion contributed to cynicism. Stress because of a lack of resources, active coping strategies and not coping passively seem to impact on professional efficacy. Opsomming Die doelstelling van hierdie navorsing was om die verband tussen coping, stres en uitbranding binne die Suid-Afrikaanse Polisiediens te ondersoek. ’n Opname-ontwerp is gebruik. Die studiepopulasie (N = 257) het bestaan uit polisiepersoneel in Kwazulu-Natal. Die COPE, die Polisiestres-Opname en die Maslach-uitbrandingsvraelys – Algemene Opname (MBI-GS) is as meetinstrumente gebruik. Strukturele vergelykingsmodellering het aangetoon dat werkseise (as stressore) geassosieer word met uitputting. Passiewe coping- strategieë het bygedra tot uitputting en sinisme, terwyl die soeke na emosionele ondersteuning tot laer uitputting gelei het. Uitputting het tot sinisme bygedra. Stres a.g.v. ’n tekort aan hulpbronne (invers), aktiewe coping-strategieë en passiewe coping-strategieë (invers) blyk ’n uitwerking op professionele doeltreffendheid te hê.

The relationship between burnout, personality traits and coping strategies in a corporate pharmaceutical group

The objective of this research was to determine the relationship between burnout, personality traits and coping strategies. A survey design was used. The study population consisted of 131 employees in a corporate pharmaceutical group. The Maslach Burnout Inventory, NEO Personality Inventory Revised and COPE were administered. Active coping strategies were associated with Emotional Stability, Extraversion, Openness to Experience and Conscientiousness, while passive coping strategies were associated with Neuroticism, low Agreeableness and low Conscientiousness. Emotional Stability, Extraversion, Openness to Experience, Agreeableness and Conscientiousness were associated with lower emotional exhaustion and depersonalisation and higher personal accomplishment. Constructive coping strategies were associated with personal accomplishment. Opsomming Die doelstelling van hierdie navorsing was om te bepaal of daar ’n verband tussen uitbranding, persoonlikheidstrekke en coping-strategieë bestaan. ’n Opnameontwerp is gebruik. Die ondersoekgroep het bestaan uit 131 werknemers van ’n korporatiewe apteekgroep. Drie vraelyste is gebruik, naamlik die Maslach-Uitbrandingsvraelys, die NEO Personality Inventory Revised en die COPE. Aktiewe coping-strategieë is geassosieer met Emosionele Stabiliteit, Ekstroversie, Openheid vir Ervaring en Konsensieusheid, terwyl passiewe coping-strategieë geassosieer is met Neurotisisme, lae Inskiklikheid en lae Konsensieusheid. Emosionele Stabiliteit, Ekstroversie, Openheid vir Ervaring, Inskiklikheid en Konsensieusheid is geassosieer met lae emosionele uitputting, lae depersonalisasie en hoë persoonlike bereiking. Konstruktiewe coping-strategieë is geassosieer met persoonlike bereiking.

The M34T allele variant of connexin 26

GJB2 encodes the protein Connexin 26, one of the building blocks of gap junctions. Each Connexin 26 molecule can oligomerize with five other connexins to form a connexon; two connexons, in turn, can form a gap junction. Because mutations in GJB2 are the most common cause of congenital severe-to-profound autosomal recessive nonsyndromic hearing loss, the effect of the Connexin 26 allele variants on this dynamic 'construction' process and the function of any gap junctions that do form is particularly germane. One of the more controversial allele variants, M34T, has been hypothesized to cause autosomal dominant nonsyndromic hearing loss. In this paper, we present clinical and genotypic data that refutes this hypothesis and suggests that the effect of the M34T allele variant may be dependent on the mutations segregating in the opposing allele.

The clinical pharmacokinetics of a new pharmacokinetically enhanced formulation of amoxicillin/clavulanate

BACKGROUND

A new oral pharmacokinetically enhanced formulation of the broad-spectrum antibiotic amoxicillin/clavulanate has been developed to provide more effective therapy against resistant pathogens than is provided by currently available formulations by maintaining therapeutically useful plasma amoxicillin concentrations for a longer period after dosing.

OBJECTIVE

This study explored the pharmacokinetics of the new oral formulation of amoxicillin/clavulanate in healthy male and female subjects.

METHODS

A single oral dose of pharmacokinetically enhanced amoxicillin/clavulanate (2000/125 mg; 16:1 ratio) was administered to subjects at the start of a meal. After dosing, blood samples were collected at frequent intervals up to 12 hours, and plasma was assayed for amoxicillin and clavulanate concentrations using validated procedures. The new formulation consisted of 1 layer of immediate-release amoxicillin and clavulanate and another of sustained-release amoxicillin in a proportion such that for an amoxicillin minimum inhibitory concentration (MIC) of 4 microg/mL, the time above the MIC (T >MIC) would be approximately > or = 40% over a 12-hour dosing interval.

RESULTS

The study enrolled 24 and 31 healthy male and female subjects, respectively. Their mean age was 35 years (range, 18-58 years) and mean body weight was 69 kg (range, 51-86 kg). After the expected sharp peak in plasma amoxicillin concentration, there appeared to be a slower decline with the pharmacokinetically enhanced formulation than is usually seen with conventional formulations, and there was evidence of a second amoxicillin absorption phase. The mean T >MIC for an amoxicillin MIC of 4 microg/mL was 49.4% of a 12-hour dosing interval, a value that cannot be achieved with existing approved doses and formulations of amoxicillin/clavulanate. By 12 hours, plasma amoxicillin concentrations were very low (approximately 0.05 microg/mL), suggesting no expectation of notable dose-to-dose accumulation on repeat dosing with a BID regimen. The terminal half-lives of amoxicillin (1.27 hours) and clavulanate (1.03 hours) with the new formulation were similar to those of existing formulations of amoxicillin/clavulanate. No deaths or serious adverse events were reported.

CONCLUSIONS

The enhanced pharmacokinetic profile of amoxicillin/clavulanate seen in this study suggests that this formulation is likely to be highly effective for the oral treatment of infections caused by bacteria--including beta-lactamase-producing organisms--and strains with amoxicillin MICs < or = 4 microg/mL.

Determination of the carrier frequency of the common GJB2 (connexin-26) 35delG mutation in the Belgian population using an easy and reliable screening method

Mutations in the gene GJB2, encoding the gap-junction protein connexin-26, have been shown to be a major cause of nonsyndromic recessive deafness (NSRD). A single mutation in the GJB2 gene accounts for the majority of NSRD in many different populations. This mutation represents a deletion of a guanine within a stretch of six Gs between nucleotide positions +30 and +35 of the GJB2 cDNA (35delG). Molecular detection of the 35delG mutation is usually performed by direct sequencing analysis of PCR products, or by allele-specific PCR analysis. To screen for this mutation, we developed an easier and more reliable method, based on the principle of PCR-mediated site-directed mutagenesis (PSDM), followed by a BsiYI digestion. We tested 360 unrelated unaffected Belgian individuals for heterozygosity of the 35delG mutation and found a carrier frequency of 1 in 40 (95% CI, 1 in 30 to 1 in 60). As our new screening method is simple and reliable in use, and detects a mutation responsible for a significant part of NSRD, it may find widespread use in DNA diagnostics.

CAG repeat contraction in the androgen receptor gene in three brothers with mental retardation

We report on three brothers with mental retardation and a contracted CAG repeat in the androgen receptor (AR) gene. It is known that expansion of the CAG repeat in this gene leads to spinal and bulbar muscular atrophy (SBMA or Kennedy disease); however, contracted repeats have not yet been implicated in disease. As the range of the length of CAG repeats in the AR gene, like those of other genes associated with dynamic mutations, follows a normal distribution, the theoretical possibility of disease at both ends of the distribution should be considered.

Classical Friedreich's ataxia and its genotype

Fourteen patients with classical features of Friedreich's ataxia (FRDA) were examined. The clinical diagnosis of FRDA was afterwards confirmed in all patients by the appropriate DNA investigation which showed markedly increased amounts of GAA repeats on both alleles of the frataxin gene. None of our patients presented with atypical features such as late-onset FRDA, FRDA with retained deep tendon reflexes or with a very slow course. Five of them are not yet confined to a wheelchair. But for 1 patient who died at age 36 years and had the largest number of GAA repeats on both alleles, there was no significant correlation between number of repeats in the shortest allele, age at onset, age at wheelchair dependence, duration of the disease and main clinical signs. All patients but 3 had between 500 and 1,050 GAA repeats. The 3 patients with, respectively, 400, 450 and 500 repeats on the shortest allele had a clinical course comparable to the other patients. Even in the case of variations in the number of repeats in the same sibship, there were only modest differences between the siblings concerning age at onset of the disease, symptoms and signs and age at wheelchair dependence. There were no qualitative differences in the main clinical features and laboratory investigations in the full-blown phase of the disorder. Molecular biology has become a major element in the diagnosis of FRDA. DNA testing for FRDA should be applied to every case of idiopathic autosomal recessive or sporadic ataxia. However, the clinical features of FRDA remain fully characteristic in many patients and keep their diagnostic value.

Incomplete EcoRI digestion may lead to false diagnosis of fragile X syndrome

Molecular diagnosis of fragile X syndrome is usually performed using Southern blot analysis of DNA digested with EcoRI. In the course of diagnostic studies, we observed that a specific EcoRI restriction site in the fragile X gene (FMR1) is sometimes refractory to digestion, generating additional fragments on a Southern blot suggestive of a full mutation in FMR1. This may lead to a false-positive diagnosis of fragile X syndrome. Such additional bands are avoided by the use of HindIII instead of EcoRI. Therefore, we recommend the use of HindIII for the molecular diagnosis of fragile X syndrome.

Copper treatment increases recombinant baculovirus production and polyhedrin and p10 expression

Treatment with 2 mM CuSO4 was used to induce a Drosophila melanogaster metallothionein (Mtn) promoter that had been cloned into a recombinant baculovirus. Careful study revealed that the Mtn promoter functioned as an inducible, if somewhat "leaky" promoter within the context of baculovirus-infected cells. In the process of generating a recombinant-baculovirus, it was discovered that post-transfection treatment with copper resulted in a 10-fold increase in the production of recombinant virus. This effect on virus production was specific to transfection, as treatment of infected cells with copper did not increase the production of virus. Treatment of infected cells with copper did, however, extend the period of expression of the polyhedrin and p10 proteins by at least 12 h. These findings have practical applications for the production of recombinant baculoviruses and the subsequent expression of foreign proteins using baculovirus expression vectors.

Mildly impaired water maze performance in male Fmr1 knockout mice

Fmr1 knockout mice constitute a putative model of fragile X syndrome, the most common form of heritable mental disability in humans. We have compared the performance of transgenic mice with an Fmr1 knockout with that of normal littermates in hidden- and visible-platform water maze learning, and showed that knockouts exhibit subnormal spatial learning abilities and marginal motor performance deficits. During 12 training trials of the hidden-platform task, escape latency and path length decreased significantly in knockouts and control littermates, and no effect of genotype was found. During four ensuing reversal trials, however, significant differences were found between knockouts and control littermates both in escape latency and path length. During the visible-platform condition, the reversal trials also revealed a difference between knockouts and normal littermates in escape latency, but not in path length. Possibly due to marginal motor incapacity, knockouts swam significantly slower than controls during these latter trials. During both probe trials of the hidden-platform task, knockouts as well as normal littermates spent more time in the target quadrant than in the other quadrants, and percent of time spent in the target quadrant was the same in both groups; swimming velocity was not significantly different between knockouts and normal littermates during these trials. Entries in the target area during the probe trials did show a significant effect of genotype on number of entries. The present results largely confirm and extend our previous findings. Impaired spatial abilities in Fmr1 knockouts might have been due to relatively low response flexibility or high memory interference in Fmr1 knockouts. It remains unclear, however, which brain region or neurochemical system might be involved in these disabilities. We conclude that Fmr1 knockout mice might be a valid model of fragile X mental retardation.

Overexpression of actin in AcMNPV-infected cells interferes with polyhedrin synthesis and polyhedra formation

Autographa californica M nuclear polyhedrosis virus (AcMNPV) terminates host protein synthesis during the late stage of infection, at approximately 14 hr postinfection (hpi). If infection takes place in the presence of cytochalasin D (CD), however, host actin synthesis is transiently stimulated and continues to be synthesized until approximately 30 hpi, and the hyperexpression of polyhedrin is delayed from about 20 hpi until about 36 hpi (S. N. Talhouk and L. E. Volkman, Virology 182, 626-634, 1991; N. Wei and L. E. Volkman, Virology 191, 42-48, 1992). To investigate whether these events are causally related, i.e., whether actin synthesis negatively affects polyhedrin synthesis, we constructed recombinant viruses that expressed actin at various levels during infection. We found that the expression of actin by a strong promoter interfered with polyhedrin synthesis at a posttranscriptional level. It also interfered with polyhedra formation, which may suggest a mechanism for the observed paucity of polyhedra in infected midgut columnar epithelial cells in vivo.

Transgenic mouse model for the fragile X syndrome

Transgenic fragile X knockout mice have been constructed to provide an animal model to study the physiologic function of the fragile X gene (FMR1) and to gain more insight into the clinical phenotype caused by the absence of the fragile X protein. Initial experiments suggested that the knockout mice show macroorchidism and cognitive and behavioral deficits, abnormalities comparable to those of human fragile X patients. In the present study, we have extended our experiments, and conclude that the Fmr1 knockout mouse is a reliable transgenic model to study the fragile X syndrome.

Severe mental retardation and macroorchidism without mutation in the FMR1 gene

Only one missense mutation, an Ile304Asn, has been reported in the fragile X gene (FMR1). This mutation is located in the second KH domain of FMR1, and has led to the discovery of the function of the FMR1 gene product as an RNA-binding protein. The patient carrying this mutation has profound mental retardation, macroorchidism, and an "acromegalic" face with prominent supraorbital ridges, enlarged jaw, heavy brow ridges, thick lips, and a broad nose. We have studied the possible involvement of FMR1 in two maternal half-brothers with a phenotype similar to that of the patient with the Ile304Asn mutation. Both brothers had an identical number of CGG repeats in the normal size-range, and shared the same maternal Xq27 haplotype. Southern blot analysis with two overlapping FMR1 cDNA clones, spanning the total FMR1 open reading frame, showed no major deletions, insertions, or gross rearrangements. Single-strand conformation pattern (SSCP) analysis of the KH domains showed no aberrant patterns. The total open reading frame of the FMR1 gene was cloned and sequenced, but no mutation was found. Northern blot analysis showed mRNA in the normal size-range, and immunocytochemistry on individual lymphocytes indicated that FMRP, the protein product of FMR1, was present. In conclusion, it is unlikely that FMR1 plays a role in the phenotype of this patient. Other genes may be responsible for the combination of mental retardation and macroorchidism.