[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.

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.

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.

A new member of the IL-1 receptor family highly expressed in hippocampus and involved in X-linked mental retardation.

We demonstrate here the importance of interleukin signalling pathways in cognitive function and the normal physiology of the CNS. Thorough investigation of an MRX critical region in Xp22.1-21.3 enabled us to identify a new gene expressed in brain that is responsible for a non-specific form of X-linked mental retardation. This gene encodes a 696 amino acid protein that has homology to IL-1 receptor accessory proteins. Non-overlapping deletions and a nonsense mutation in this gene were identified in patients with cognitive impairment only. Its high level of expression in post-natal brain structures involved in the hippocampal memory system suggests a specialized role for this new gene in the physiological processes underlying memory and learning abilities.

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.

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.

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.

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.

Down syndrome in a population of elderly mentally retarded patients: genetic-diagnostic survey and implications for medical care.

Ninety-six adults with Down syndrome (DS) from an institutional setting of 591 mentally retarded were investigated systematically with respect to cytogenetic diagnosis, mental functioning and dementia, ophthalmological and audiological abnormalities, and thyroid function. Seventy of the 96 DS patients (73%) were older than 40 years. Only 4.2% were females. Trisomy 21 was found in 86% and mosaic trisomy 21 in 13%. Eighty-two percent of the patients were moderately or severely mentally retarded, 15% were profoundly retarded, and only 3% mildly retarded. Nineteen percent of the patients had dementia. This number increased to 42% of the patients above the age of 50 years. Epileptic seizures were present in 16.7% of all patients, and in 50% of the patients with dementia. Only 17% of the patients in the present study had normal visual acuity, one-third had at least moderately reduced vision. This number increased significantly with age: in the age group 50-59 years almost half of the patients had moderate to severe vision loss. Seventy percent of the patients had moderate, severe, or very severe hearing loss, which was undiagnosed before systematic hearing testing was performed. Increased (48%) or decreased (1%) TSH level was found in 49% of the patients examined for thyroid functions. We suggest a regular screening of all adults with DS to diagnose early dementia, epilepsy, hypothyroidism, and early loss of visual acuity and hearing, with special attention to the group of patients who are severely to profoundly mentally retarded and those with advanced age. Cytogenetic studies are necessary to confirm the clinical diagnosis and are essential for genetic counseling purposes.

Structural chromosome rearrangements in couples with recurrent fetal wastage.

OBJECTIVE: A review of the cytogenetic data in 1743 couples (3486 patients) with recurrent fetal wastage (RFW) who were examined for RFW at the Leuven Centre for Human Genetics in the period 1986-1995. These results were compared with a previous study in the period 1970-1985. SUBJECTS: Patients who had at least two first trimester miscarriages or patients who had a spontaneous first trimester abortion, preceded or followed by a second or third trimester fetal death. RESULTS: Chromosomal rearrangements were found in 5.34%. Two-thirds of these chromosomal rearrangements were autosomal balanced translocations. This finding is a 30-fold increase compared to the general population. Other chromosomal abnormalities included Robertsonian translocations, inversions and sex-chromosomal abnormalities. DISCUSSION: The Leuven experience was compared with several other studies. Mechanisms causing these chromosomal abnormalities are presented. CONCLUSIONS: Chromosomal analyses are an important and necessary part of the etiological investigations in couples with RFW.

A distinct phenotype associated with partial trisomy 10q due to proximal direct duplication 10q11 --> q223?

We describe a 15-months-old female child with proximal 10q trisomy due to direct duplication 10q11 --> q223. Reviewing the literature a further delineation of the clinical phenotype of this rare chromosomal abnormality is proposed. The main clinical features associated with 10q11-q22 duplication are: mild to moderate mental retardation, microcephaly, postnatal growth retardation, ocular malformations, heart defects, abnormalities of the extremities and typical facies with thin, bowed upper lip, upturned nasal tip, high palate, small chin and everted ears.

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.

Partial trisomy 4q due to a maternal translocation: t(4;18)(q27;q21.31).

We report on a second trimester female fetus with 4q duplication (4q27-->4qter) and 18q deficiency (18q21.31-->qter) as the unbalanced product of a t(4;18)(q27;q21.31)mat. On fetopathological examination this fetus presented clinical features suggestive of the diagnosis of trisomy 18. A review is given of other reported patients with 4q duplication/18q deficiency.

13q deletion syndrome in an adult mentally retarded patient.

Clinical features of the 13q deletion syndrome are difficult to define and include retinoblastoma, mental and growth retardation, craniofacial abnormalities, brain, gastrointestinal, renal and heart malformations, anal atresia and limb and digit malformations. The critical region for development of major organ systems has been defined in 13q32 between the proximal marker 13S132 and distal marker D13S147. We report a severely mentally retarded male patient with a deletion of the distal part of chromosome 13 (13q32.3-->qter) without major organ malformations.

Progressive pseudorheumatoid dysplasia: report of a patient with symptoms present at birth.

Progressive pseudorheumatoid dysplasia (spondyloepiphyseal dysplasia tarda with progressive arthropathy (SEDTPA) or progressive pseudorheumatoid arthropathy of childhood (PPAC) (MIM 208.230)) is an autosomal recessively inherited skeletal dysplasia with changes in the spine similar to spondyloepiphyseal dysplasia tarda. The disease begins mostly between the ages of 2 to 8 years with progressive joint stiffness and pain, soft tissue swelling and deformities of multiple joints including the proximal interphalangeal joints of the hands. We describe a patient where a symmetric rhizomelic shortening of the extremities and a bilateral severe pes equinovarus was present at birth.

Björnstad syndrome in a patient with mental retardation.

Björnstad syndrome in a patient with mental retardation: Pili torti or twisted hair can appear as an isolated defect, in association with other ectodermal defects, in association with other clinical features or can be acquired. Björnstad syndrome is a rare condition with apparent autosomal recessive inheritance, characterized by hearing loss and twisted hairs (pili torti). All patients with Björnstad syndrome reported thusfar have normal intelligence. We report on a patient with severe mental retardation and review the literature.

Zimmermann-Laband syndrome in a patient with severe mental retardation.

Zimmermann-Laband syndrome in a patient with severe mental retardation: The Zimmermann-Laband syndrome (ZLS) is a rare autosomal dominant disorder characterized by gingival hyperplasia or fibromatosis, various skeletal anomalies including dysplasia of the distal phalanges of thumbs and halluces, vertebral defects, and hepatosplenomegaly. Thus far, 23 cases, including 11 patients from 2 families, have been reported. Most cases of ZLS have a normal intelligence although some cases are mildly retarded. Differential diagnosis includes other causes of gingival hyperplasia. We report on a patient with ZLS and severe mental retardation and review the literature. We conclude that severe mental retardation is a feature of the syndrome.