[Adolescent with a schizophreniform disorder and recurrent 16p11.2 duplication]. / Adolescent met schizofreniforme stoornis en terugkerende 16p11.2-duplicatie.

Genetic factors play an important role in the development of psychotic disorders. With increasing evidence, several rare copy number variants (cnvs) have been identified as risk factors. We describe a patient who had two psychotic episodes during his adolescence. In this patient, a 16p11.2 duplication was detected. This duplication is a recurrent cnv associated with various somatic and psychiatric phenotypes including psychosis and schizophrenia. The potential clinical relevance of this finding is discussed.

Facial dysmorphism is influenced by ethnic background of the patient and of the evaluator.

The evaluation of facial dysmorphism is a critical step toward reaching a diagnostic. The aim of the present study was to evaluate the ability to interpret facial morphology in African children with intellectual disability (ID). First, 10 experienced clinicians (five from Africa and five from Europe) rated gestalt in 127 African non-Down Syndrome (non-DS) patients using either the score 2 for 'clearly dysmorphic', 0 for 'clearly non dysmorphic' or 1 for 'uncertain'. The inter-rater agreement was determined using kappa coefficient. There was only fair agreement between African and European raters (kappa-coefficient = 0.29). Second, we applied the FDNA Face2Gene solution to assess Down Syndrome (DS) faces. Initially, Face2Gene showed a better recognition rate for DS in Caucasian (80%) compared to African (36.8%). We trained the Face2Gene with a set of African DS and non-DS photographs. Interestingly, the recognition in African increased to 94.7%. Thus, training improved the sensitivity of Face2Gene. Our data suggest that human based evaluation is influenced by ethnic background of the evaluator. In addition, computer based evaluation indicates that the ethnic of the patient also influences the evaluation and that training may increase the detection specificity for a particular ethnic.

Whole gene duplication of SCN2A and SCN3A is associated with neonatal seizures and a normal intellectual development.

Duplications at 2q24.3 encompassing the voltage-gated sodium channel gene cluster are associated with early onset epilepsy. All cases described in the literature have presented in addition with different degrees of intellectual disability, and have involved neighbouring genes in addition to the sodium channel gene cluster. Here, we report eight new cases with overlapping duplications at 2q24 ranging from 0.05 to 7.63 Mb in size. Taken together with the previously reported cases, our study suggests that having an extra copy of SCN2A has an effect on epilepsy pathogenesis, causing benign familial infantile seizures which eventually disappear at the age of 1-2 years. However, the number of copies of SCN2A does not appear to have an effect on cognitive outcome.

Social cognition and underlying cognitive mechanisms in children with an extra X chromosome: a comparison with autism spectrum disorder.

Individuals with an extra X chromosome are at increased risk for autism symptoms. This study is the first to assess theory of mind and facial affect labeling in children with an extra X chromosome. Forty-six children with an extra X chromosome (29 boys with Klinefelter syndrome and 17 girls with Trisomy X), 56 children with autism spectrum disorder (ASD) and 88 non-clinical controls, aged 9-18 years, were included. Similar to children with ASD, children with an extra X chromosome showed significant impairments in social cognition. Regression analyses showed that different cognitive functions predicted social cognitive skills in the extra X and ASD groups. The social cognitive deficits were similar for boys and girls with an extra X chromosome, and not specific for a subgroup with high Autism Diagnostic Interview Revised autism scores. Thus, children with an extra X chromosome show social cognitive deficits, which may contribute to social dysfunction, not only in children showing a developmental pattern that is 'typical' for autism but also in those showing mild or late presenting autism symptoms. Our findings may also help explain variance in type of social deficit: children may show similar social difficulties, but these may arise as a consequence of different underlying information processing deficits.

Microduplication 22q11.2: a description of the clinical, developmental and behavioral characteristics during childhood.

Microduplication 22q11.2 is a recently discovered genomic disorder. So far, targeted research on the cognitive and behavioral characteristics of individuals with this microduplication is limited. Therefore, 11 Flemish children (3-13 years old) with a microduplication 22q 1.2 were investigated in order to describe their clinical, developmental and behavioral characteristics. We measured their general intelligence, visual-motor capacities, attention, behavioral problems and characteristics of autism. In addition, there was an interview with the parents on developmental history and we reviewed available information from other specialists. The results show that the cognitive and behavioral phenotype of the children with microduplication 22q.11.2 is very wide and heterogeneous. Some of the children have a cognitively nearly normal development whereas others are more severely affected. All children had some degree of developmental delay and some of them have an intellectual disability. The most common clinical features include congenital malformations such as heart defects and cleft lip, feeding problems, hearing impairment and facial dysmorphism. The most common non-medical problems are learning difficulties, motor impairment, attention deficits, social problems and behavioral problems. There is no correlation between the size of the duplication and the phenotype.

Neuropsychopathology in 7 Patients with the 22q13 Deletion Syndrome: Presence of Bipolar Disorder and Progressive Loss of Skills.

The 22q13 deletion syndrome is characterised by intellectual disability (ID), delayed or absent speech, autistic-like behaviour and minor, nonspecific dysmorphic features. The deletion of the SHANK3 gene is thought to be responsible for these features. In this study, the clinical data of 7 patients with the 22q13 deletion syndrome are presented, obtained by clinical genetic examination, direct behavioural observation and by interview of family members and/or caregivers, complemented by behavioural questionnaires. The specific focus was on behaviour, psychopathology and the level of functioning during life course in order to determine common features that might contribute to the delineation of the syndrome. Major findings were a high incidence of psychiatric disorders, more in particular bipolar disorder (BPD) and attention deficit hyperactivity disorder (ADHD), and a sudden deterioration after acute events, in addition to a progressive loss of skills over years. Therefore, a deletion of SHANK3 may result in a dysfunctional nervous system, more susceptible to developmental problems and psychiatric disorders on the one hand, less able to recuperate after psychiatric and somatic events, and more vulnerable to degeneration at long term on the other hand. These results are exploratory and need to be confirmed in a larger sample.

Recurrent reciprocal deletions and duplications of 16p13.11: the deletion is a risk factor for MR/MCA while the duplication may be a rare benign variant.

BACKGROUND: Genomic disorders are often caused by non-allelic homologous recombination between segmental duplications. Chromosome 16 is especially rich in a chromosome-specific low copy repeat, termed LCR16. METHODS AND RESULTS: A bacterial artificial chromosome (BAC) array comparative genome hybridisation (CGH) screen of 1027 patients with mental retardation and/or multiple congenital anomalies (MR/MCA) was performed. The BAC array CGH screen identified five patients with deletions and five with apparently reciprocal duplications of 16p13 covering 1.65 Mb, including 15 RefSeq genes. In addition, three atypical rearrangements overlapping or flanking this region were found. Fine mapping by high-resolution oligonucleotide arrays suggests that these deletions and duplications result from non-allelic homologous recombination (NAHR) between distinct LCR16 subunits with >99% sequence identity. Deletions and duplications were either de novo or inherited from unaffected parents. To determine whether these imbalances are associated with the MR/MCA phenotype or whether they might be benign variants, a population of 2014 normal controls was screened. The absence of deletions in the control population showed that 16p13.11 deletions are significantly associated with MR/MCA (p = 0.0048). Despite phenotypic variability, common features were identified: three patients with deletions presented with MR, microcephaly and epilepsy (two of these had also short stature), and two other deletion carriers ascertained prenatally presented with cleft lip and midline defects. In contrast to its previous association with autism, the duplication seems to be a common variant in the population (5/1682, 0.29%). CONCLUSION: These findings indicate that deletions inherited from clinically normal parents are likely to be causal for the patients' phenotype whereas the role of duplications (de novo or inherited) in the phenotype remains uncertain. This difference in knowledge regarding the clinical relevance of the deletion and the duplication causes a paradigm shift in (cyto)genetic counselling.

Genotype-phenotype correlation in 21 patients with Wolf-Hirschhorn syndrome using high resolution array comparative genome hybridisation (CGH).

BACKGROUND: The Wolf-Hirschhorn syndrome (WHS) is usually caused by terminal deletions of the short arm of chromosome 4 and is phenotypically defined by growth and mental retardation, seizures, and specific craniofacial manifestations. Large variation is observed in phenotypic expression of these features. In order to compare the phenotype with the genotype, we localised the breakpoints of the 4 pter aberrations using a chromosome 4 specific tiling BAC/PAC array. METHODS: In total, DNA from 21 patients was analysed, of which 8 had a cytogenetic visible and 13 a submicroscopic deletion. RESULTS AND CONCLUSION: In addition to classical terminal deletions sized between 1.9 and 30 Mb, we observed the smallest terminal deletion (1.4 Mb) ever reported in a patient with mild WHS stigmata. In addition, we identified and mapped interstitial deletions in four patients. This study positions the genes causing microcephaly, intrauterine and postnatal growth retardation between 0.3 and 1.4 Mb and further refines the regions causing congenital heart disease, cleft lip and/or palate, oligodontia, and hypospadias.

The t(4;8) is mediated by homologous recombination between olfactory receptor gene clusters, but other 4p16 translocations occur at random.

The t(4;8)(p16;p23) is the second most common constitutional chromosomal translocation and is caused by an ectopic meiotic recombination between the olfactory receptor gene clusters (ORGC), located on chromosome 4p and 8p. Given that ORGCs are scattered across the genome and make-up about 0.1% of the human genome we reasoned that translocations between 4p16 and other chromosomes might be mediated by ectopic recombination between different ORGC. In 13 patients, we mapped the breakpoints of either a balanced or unbalanced translocation between chromosome 4p16 and different chromosomes. For all four t(4;8) cases, the breakpoints fall within the 4p and 8pter ORGC, confirming that non-allelic homologous recombination (NAHR) between the ORGC is the main mechanism of the t(4;8) formation. For the nine other translocations, the breakpoints on chromosome 4 mapped to different loci, one of them within the ORGC and in two flanking the ORGC. In these three cases, the translocation breakpoint at the reciprocal chromosome did not contain ORGC sequences. We conclude that only the t(4;8) is mediated by NAHR between ORGC.

4q35 deletion and 10p15 duplication associated with immunodeficiency.

We report a familial cryptic reciprocal translocation between 4q35 and 10p15 leading to deletion of the terminal long arm of chromosome 4 and duplication of the terminal short arm of chromosome 10 in two family members who both have immunological disturbances and a similar facial appearance. The precise location and extent of the deletion and duplication was determined by fluorescence in situ hybridization (FISH). Furthermore, we investigated the deletion breakpoint of a previously reported patient with 4q34.3-qter deletion [Van Buggenhout et al. (2004); Am J Med Genet Part A 131A:186-189].

The del(2)(q32.2q33) deletion syndrome defined by clinical and molecular characterization of four patients.

We report four patients with an interstitial deletion of chromosome 2q32-->2q33. They presented similar clinical findings including pre- and postnatal growth retardation, distinct facial dysmorphism, thin and sparse hair and fair built, micrognathia, cleft or high palate, relative macroglossia, dacrocystitis, persisting feeding difficulties, inguinal hernia and broad based gait. All were severely mentally retarded. Three patients had a specific behavioral phenotype with hyperactivity and motor restlessness, chaotic behavior, happy-personality but with periods of aggression and anxiety, sleeping problems and self-mutilation. (head-banging). Array CGH and fluorescence in situ hybridization (FISH) allowed us to delineate the deletion size and showed that the four patients share a 8.1 Mb minimal deleted region. Reviewing additional nine case reports of patients with similar deletions showed striking phenotypic similarities which enabled the delineation of the 2q32.2q33 syndrome. Deletion of 2q32 has been also associated with the wrinkly skin syndrome (WWS) and isolated cleft palate. Although the patients presented here shared many aspects of WWS, they did not had the wrinkly skin. All patients had a cleft or high palate, most likely as a result of hemizygosity for SATB2. A potential commonly deleted interval of the three patients with behavioral problems, excluding the deletion in the patient without behavioral problems, is at most 0.5 Mb in size harboring only two genes.

Pericentric inversion with partial 7(q35-->qter) duplication and 7pter deletion: diagnosis by cytogenetic and fish analysis in a 29-year-old male patient.

We report on a 29-year-old male patient with an inverted 7(q35-qter) duplication diagnosed by combining cytogenetic and FISH studies. Traditional G-banding detected an abnormally long chromosome 7 which was further demonstrated to be entirely of chromosome 7 origin by using fluorescent whole chromosome 7 painting. The presence within the additional segment of a signal for 7q36 region (Williams control probe) and the absence of signals for 7q33 (Y938G5 probe) and 7q34 (Y815G5 probe) regions indicated that the breakpoint for this rearrangement was distal to 7q34 and proximal to 7q36. A distal 7p22 deletion was confirmed by the absence of signal for the 7p subtelomeric probe. Apart from kyphosis, developmental/mental retardation and abnormal ears, the clinical features of the present patient, who is the oldest individual ever reported with this duplication/deletion, were not typical for partial 7q trisomy syndrome. A review of the cases reported with 7(q35-qter) duplication is made and shows important clinical variability but constantly normal pre- and postnatal growth, a feature which can therefore be confirmed as distinctive of distal 7q trisomy syndrome.

Dysmorphology and mental retardation: molecular cytogenetic studies in dysmorphic mentally retarded patients.

In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 18 patients (16 males and 2 females) with dysmorphic features were selected to perform FISH studies by using subtelomeric probes to discover cryptic terminal deletions or duplications, undetectable with standard banding techniques. In the 13 investigated patients, no abnormalities were found with a selected battery of subtelomeric probes. The results of cryptic chromosomal rearrangement studies are variable but the frequency of positive diagnostic findings seems to be lower than previously expected.

Metabolic studies in older mentally retarded patients: significance of metabolic testing and correlation with the clinical phenotype.

In 471 adult mentally retarded adult patients (mean age 46 years; 92.6% males) living in an institution for the mentally retarded, a clinical examination, cytogenetic and molecular studies were done. 306 patients were screened for metabolic disorders. In 7 additional patients a metabolic disorder (phenylketonuria (n = 5), mucopolysaccharidosis type III (Sanfilippo syndrome, type A) (n = 1) and mucopolysaccharidosis type VII (Sly syndrome) (n = 1)) was diagnosed in the past. The abnormal metabolic findings in this group of 313 patients were classified in three categories and the clinical findings are reported: 1. metabolic disorders as the cause of mental retardation (MR), 2. metabolic disorders not explaining the MR, and 3. metabolic abnormalities of unknown significance. The first two groups included 16 patients, i.e. 26.2% of the group of monogenic disorders and 3.4% of the total population: phenylketonuria (PKU) (n = 5), S-sulfocysteinuria (n = 3), mucopolysaccharidosis type III (Sanfilippo syndrome, type A) (n = 1) and Gm1-gangliosidosis type 3 (n = 1) (first group), and mucopolysaccharidosis type VII (Sly syndrome) (n = 1), Niemann-Pick syndrome, type B (n = 1), cystinuria (n = 1) and hyperprolinemia type 1 (n = 3) (second group). The third group included patients with citrullinemia (n = 2), methionine sulphoxide reductase deficiency (n = 1), ornithinemia (n = 1), glycinuria (n = 20), neuraminaciduria (n = 8), uraciluria (n = 6) and diabetes mellitus (n = 2). Screening for Congenital Disorders of Glycosylation (CDG) in 144 patients and for Smith-Lemli-Opitz syndrome (SLO) in a selected group of 6 patients was normal. Of the total group of 306 patients screened for inborn errors of metabolism, only 5 (1.6%) were found with a true metabolic disorder. These 5 patients presented clinical symptoms, neurodegenerative or behavioural problems, indicating further metabolic screening. The present study illustrates that a selected group of patients with mental retardation of unknown origin are candidates for metabolic screening, especially if aberrant behaviour, neurodegenerative problems or dysmorphic features are present.

The clinical phenotype in institutionalised adult males with X-linked mental retardation (XLMR).

In an institutionalised population of 471 mentally retarded adult residents (436 males and 35 females), 22 males (i.e. 5 % of the male population) had XLMR, accounting for 36.1 % of the residents diagnosed with a monogenic disorder (n = 61). Fragile X syndrome (FRAXA) was diagnosed in 16 residents, X-linked mental retardation with marfanoid habitus (Lujan-Fryns syndrome) in 2, and non-specific X-linked mental retardation (MRX) in 4 males. The 4 MRX-patients included 3 male sibs of a family, carrying a mutation in the IL-1 receptor accessory protein-like gene, and one male patient member of the MRX-44 family (linkage with LOD-score of 2.90). In the group of 215 males with idiopathic mental retardation (MR), family histories and pedigree data were compatible with XLMR in 35 males (35/215 = 16.3 %) from 32 families. Of these 35 males, 5.7 % were microcephalic with dysmorphic features and 5.7 % macrocephalic; micro-orchidism and macro-orchidism were each found in 11.4 %. One macrocephalic male had also macro-orchidism and dysmorphic features. In this study, the diagnosis of XLMR could thus be proposed in 57 males i.e. 13.1 % of the total male population. The clinical phenotype, behavioural problems and follow-up data in these different subgroups of XLMR are presented.

Cri du chat syndrome: changing phenotype in older patients.

The cri du chat syndrome or 5p deletion syndrome is a well-delineated clinical entity and has an incidence of 1/50,000 in newborn infants. A de novo deletion is present in 85% of the patients. Ten to 15% are familial cases with more than 90% due to a parental translocation and 5% due to an inversion of chromosome 5. Although the size of the deleted segment varies, the critical segment that is deleted in all patients appears to be 5p15.2. The clinical picture is well known in younger patients and includes the typical high-pitched cry, psychomotor retardation, microcephaly, growth rate failure, and craniofacial abnormalities including round face, hypertelorism, broad nasal bridge, downward slanting palpebral fissures, and micrognathia. With advancing age, the clinical picture becomes less striking. We present seven patients with 5p deletion syndrome, who were between age 16 and 47 years. Comparing their phenotype at several ages, a change of their phenotype was noted. Some of the clinical characteristics became more evident such as long face, macrostomia, and scoliosis. All patients were severely or profoundly mentally retarded except one patient who was mildly mentally retarded. The diagnosis was difficult to make in some of the patients who were first seen at an older age. In some of them, the craniofacial appearance resembled that seen in Angelman syndrome. Most patients had periods of destructive behavior, self mutilation, and aggression. The clinical diagnosis should be confirmed as soon as possible with cytogenetic investigation to provide specific support, prevention, and treatment of complications. Therefore, it is important to perform follow-up studies in young children to determine their outcome after infant-stimulation programs.

Angelman syndrome in three adult patients with atypical presentation and severe neurological complications.

Angelman syndrome (AS) is a distinct neurogenetic disorder and the phenotype is well known in childhood and adolescence. However, with advancing age the clinical and behavioral phenotype changes. In adulthood, the phenotype can be rather aspecific. We report on AS in 3 severely to profoundly mentally retarded patients, who developed severe neurologic complications of severe tremor, spasticity and coordination problems, resulting into severe loss of function. They presented atypical craniofacial features, short stature, epileptic seizures, microcephaly, brachytelephalangy and absent speech. Two patients presented at an older age a change in day-night rhythm. Based on this experience, we conclude that all severely to profoundly mentally retarded patients with atypical phenotype, spasticity, absent speech, epileptic seizures and changed day-night rhythm are candidates for further cytogenetic and molecular investigation for AS. Clinical photographs of the patient at a younger age can be helpful. The presence of the typical EEG pattern with frontal triphasic delta waves may direct to the diagnosis of AS.

Heterozygous germline mutations in the p53 homolog p63 are the cause of EEC syndrome.

EEC syndrome is an autosomal dominant disorder characterized by ectrodactyly, ectodermal dysplasia, and facial clefts. We have mapped the genetic defect in several EEC syndrome families to a region of chromosome 3q27 previously implicated in the EEC-like disorder, limb mammary syndrome (LMS). Analysis of the p63 gene, a homolog of p53 located in the critical LMS/EEC interval, revealed heterozygous mutations in nine unrelated EEC families. Eight mutations result in amino acid substitutions that are predicted to abolish the DNA binding capacity of p63. The ninth is a frameshift mutation that affects the p63alpha, but not p63beta and p63gamma isotypes. Transactivation studies with these mutant p63 isotypes provide a molecular explanation for the dominant character of p63 mutations in EEC syndrome.