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Chromosome 1q41-q42 deletions have recently been associated with a recognizable neurodevelopmental syndrome of early childhood (OMIM 612530). Within this group, a predominant phenotype of developmental delay (DD), intellectual disability (ID), epilepsy, distinct dysmorphology, and brain anomalies on magnetic resonance imaging/computed tomography has emerged. Previous reports of patients with de novo deletions at 1q41-q42 have led to the identification of an evolving smallest region of overlap which has included several potentially causal genes including DISP1, TP53BP2, and FBXO28. In a recent report, a cohort of patients with de novo mutations in WDR26 was described that shared many of the clinical features originally described in the 1q41-q42 microdeletion syndrome (MDS). Here, we describe a novel germline FBXO28 frameshift mutation in a 3-year-old girl with intractable epilepsy, ID, DD, and other features which overlap those of the 1q41-q42 MDS. Through a familial whole-exome sequencing study, we identified a de novo FBXO28 c.972_973delACinsG (p.Arg325GlufsX3) frameshift mutation in the proband. The frameshift and resulting premature nonsense mutation have not been reported in any genomic database. This child does not have a large 1q41-q42 deletion, nor does she harbor a WDR26 mutation. Our case joins a previously reported patient also in whom FBXO28 was affected but WDR26 was not. These findings support the idea that FBXO28 is a monogenic disease gene and contributes to the complex neurodevelopmental phenotype of the 1q41-q42 gene deletion syndrome., (© 2018 Wiley Periodicals, Inc.)

16q24 deletion involving the ANKRD11 gene, ranging from 137 kb to 2 Mb, have been associated with a microdeletion syndrome characterized by variable cognitive impairment, autism spectrum disorder, facial dysmorphisms with dental anomalies, brain abnormalities essentially affecting the corpus callosum and short stature. On the other hand, patients carrying either deletions encompassing solely ANKRD11 or its loss-of-function variants were reported in association with the KBG syndrome, characterized by a very similar phenotype, including mild-to-moderate intellectual disability, short stature and macrodontia of upper incisors, with inter and intrafamilial variability. To assess whether the haploinsufficiency of ANKRD11-flanking genes, such as ZFPM1, CDH15 and ZNF778, contributed to either the severity of the neurological impairment or was associated with other clinical features, we collected 12 new cases with a 16q24.2q24.3 deletion (de novo in 11 cases), ranging from 343 kb to 2.3 Mb. In 11 of them, the deletion involved the ANKRD11 gene, whereas in 1 case only flanking genes upstream to it were deleted. By comparing the clinical and genetic features of our patients with those previously reported, we show that the severity of the neurological phenotype and the frequency of congenital heart defects characterize the deletions that, besides ANKRD11, contain ZFPM1, CDH15 and ZNF778 as well. Moreover, the presence of thrombocytopenia and astigmatism should be taken into account to distinguish between 16q24 microdeletion syndrome and KBG syndrome. The single patient not deleted for ANKRD11, whose phenotype is characterized by milder psychomotor delay, cardiac congenital malformation, thrombocytopenia and astigmatism, confirms all this data.

We present a newborn diagnosed with posterior amorphous corneal dystrophy (PACD). PACD is a rare disorder with partial or complete posterior lamellar corneal opacification. Genetic screening showed a deletion of chromosome 12q21.33-q22 containing the identified four small leucine-rich proteoglycans (SLRP's) associated with this particular dystrophy. Neither parents were carrier of the deletion. To our knowledge, this is the first report of a de novo mutation causing PACD.

We report on seven novel patients with a submicroscopic 22q12 deletion. The common phenotype constitutes a contiguous gene deletion syndrome on chromosome 22q12.1q12.2, featuring NF2-related schwannoma of the vestibular nerve, corpus callosum agenesis and palatal defects. Combining our results with the literature, eight patients are recorded with palatal defects in association with haploinsufficiency of 22q12.1, including the MN1 gene. These observations, together with the mouse expression data and the finding of craniofacial malformations including cleft palate in a Mn1-knockout mouse model, suggest that this gene is a candidate gene for cleft palate in humans.

Solitary Median Maxillary Central Incisor occurs in 1 of 50,000 live births. It is the mildest manifestation of the holoprosencephaly spectrum and is genetically heterogeneous. Here we report six patients with solitary median maxillary central incisor, and a range of other phenotypic anomalies with different degrees of severity, varying from mild signs of holoprosencephaly to associated intellectual disability, and with different genetic background. Using array comparative genomic hybridization, pathogenic copy number variants were found in three of the six patients. Two patients had a deletion at the 18p11 chromosomal region that includes TGIF1 while the other patient had a deletion at 7q36, including the SHH gene. In one patient, a mutation in SIX3 was detected with exome sequencing, while in the two remaining patients all known holoprosencephaly genes were excluded using multiplex ligation-dependent probe amplification and sequencing, and remain unsolved. One of the two latter patients had isolated solitary median maxillary central incisor without other visible dentofacial anomalies, while the other had clinical features not part of the known holoprosencephaly spectrum., (© 2015 Wiley Periodicals, Inc.)

Purpose: Submicroscopic deletions of chromosome band 2p25.3 are associated with intellectual disability and/or central obesity. Although MYT1L is believed to be a critical gene responsible for intellectual disability, so far no unequivocal data have confirmed this hypothesis., Methods: In this study we evaluated a cohort of 22 patients (15 sporadic patients and two families) with a 2p25.3 aberration to further refine the clinical phenotype and to delineate the role of MYT1L in intellectual disability and obesity. In addition, myt1l spatiotemporal expression in zebrafish embryos was analyzed by quantitative polymerase chain reaction and whole-mount in situ hybridization., Results: Complete MYT1L deletion, intragenic deletion, or duplication was observed in all sporadic patients, in addition to two patients with a de novo point mutation in MYT1L. The familial cases comprise a 6-Mb deletion in a father and his three children and a 5' MYT1L overlapping duplication in a father and his two children. Expression analysis in zebrafish embryos shows specific myt1l expression in the developing brain., Conclusion: Our data strongly strengthen the hypothesis that MYT1L is the causal gene for the observed syndromal intellectual disability. Moreover, because 17 patients present with obesity/overweight, haploinsufficiency of MYT1L might predispose to weight problems with childhood onset.Genet Med 17 6, 460-466.

In this case report, we present a paternal transmission of a classic 3 Mb 22q11.2 deletion syndrome (22q11.2 DS) in a 3 generation family. In this family a young girl, her father, her uncle and her grandfather were diagnosed with this disorder. All carriers showed phenotypic expression, there were no unaffected siblings in the second or third generation. Presenting symptoms in the patient in first generation (grandfather) were psoriatic arthritis, thrombocytopenia and a right aortic arch. There was no intellectual disability. The second generation uncle was known with a severe intellectual disability, mild facial characteristics, a septal defect and a clubfoot, whereas the second generation father had a tetralogy of Fallot, no intellectual disability and minimal facial characteristics. The third generation daughter had a moderate intellectual disability, hypernasal speech, triphalangeal thumb, severe speech and language development delay, pronounced facial characteristics and a diagnosis of ADHD. It was notable that the expression in the two brothers of the second generation gives two very different clinical phenotypes with a severe intellectual disability in the oldest brother. This report describes a pronounced clinical variability in a 3 generation familial 22q11.2 deletion with paternal transmission. We can assume that several mechanisms play an important role in the heterogeneity and part of the answer should be found in the genetic background underlying the 22q11.2 deletion. In addition in this family the neuropsychiatric phenotype and intellectual disability seem to be associated with a lower level of social and occupational functioning while a congenital heart disease does not. This clinical report illustrates that a detailed description of these patients can be very informative and still increase the knowledge on this heterogeneous syndrome. For the clinicians working with these patients it emphasizes the need for a multidisciplinary approach that takes into account the individual needs., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Loss-of-function mutations in several different neuronal pathways have been related to intellectual disability (ID). Such mutations often are found on the X chromosome in males since they result in functional null alleles. So far, microdeletions at Xq24 reported in males always have been associated with a syndromic form of ID due to the loss of UBE2A. Here, we report on overlapping microdeletions at Xq24 that do not include UBE2A or affect its expression, in patients with non-syndromic ID plus some additional features from three unrelated families. The smallest region of overlap, confirmed by junction sequencing, harbors two members of the mitochondrial solute carrier family 25, SLC25A5 and SLC25A43. However, identification of an intragenic microdeletion including SLC25A43 but not SLC25A5 in a healthy boy excluded a role for SLC25A43 in cognition. Therefore, our findings point to SLC25A5 as a novel gene for non-syndromic ID. This highly conserved gene is expressed ubiquitously with high levels in cortex and hippocampus, and a presumed role in mitochondrial exchange of ADP/ATP. Our data indicate that SLC25A5 is involved in memory formation or establishment, which could add mitochondrial processes to the wide array of pathways that regulate normal cognitive functions.

Velocardiofacial and DiGeorge syndromes, also known as 22q11.2 deletion syndrome (22q11DS), are congenital-anomaly disorders caused by a de novo hemizygous 22q11.2 deletion mediated by meiotic nonallelic homologous recombination events between low-copy repeats, also known as segmental duplications. Although previous studies exist, each was of small size, and it remains to be determined whether there are parent-of-origin biases for the de novo 22q11.2 deletion. To address this question, we genotyped a total of 389 DNA samples from 22q11DS-affected families. A total of 219 (56%) individuals with 22q11DS had maternal origin and 170 (44%) had paternal origin of the de novo deletion, which represents a statistically significant bias for maternal origin (p = 0.0151). Combined with many smaller, previous studies, 465 (57%) individuals had maternal origin and 345 (43%) had paternal origin, amounting to a ratio of 1.35 or a 35% increase in maternal compared to paternal origin (p = 0.000028). Among 1,892 probands with the de novo 22q11.2 deletion, the average maternal age at time of conception was 29.5, and this is similar to data for the general population in individual countries. Of interest, the female recombination rate in the 22q11.2 region was about 1.6-1.7 times greater than that for males, suggesting that for this region in the genome, enhanced meiotic recombination rates, as well as other as-of-yet undefined 22q11.2-specific features, could be responsible for the observed excess in maternal origin., (Copyright © 2013 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Background: Deletions including chromosome 14 band q13 have been linked to variable phenotypes. With current molecular methods the authors aim to elucidate a genotype-phenotype correlation by accurately determining the size and location of the deletions and the associated phenotype., Methods: Here the authors report the molecular karyotyping and phenotypic description of seven patients with overlapping deletions including chromosome 14q13., Results: The authors show that deletions including 14q13 result in a recognisable phenotype mainly due to haploinsufficiency of two genes (NKX2-1, PAX9). FOXG1 (on chromosome band 14q12) involvement seems to be the main determinant of phenotype severity. The patients in this study without FOXG1 involvement and deletions of up to 10 Mb have a relatively mild phenotype. The authors cannot explain why some patients in literature with overlapping but smaller deletions appear to have a more severe phenotype. A previously presumed association with holoprosencephaly could not be confirmed as none of the patients in this series had holoprosencephaly., Conclusions: FOXG1 appears the main determinant of the severity of phenotypes resulting from deletions including 14q13. The collected data show no evidence for a locus for holoprosencephaly in the 14q13 region, but a locus for agenesis of the corpus callosum cannot be excluded.

Deletions in chromosome 14q22-23 have been associated with variable manifestations including malformations of the eye, limbs, palate, and brain, and with developmental and growth delay. Haploinsufficiency of BMP4, OTX2 and possibly SIX6 are thought to contribute to the phenotype. We present a three generation family with four individuals carrying a 2.79 Mb microdeletion 14q22.1-22.2 encompassing BMP4 but not OTX2 nor SIX6. The highly variable manifestations in this family range from multiple congenital malformations with Robin sequence, microphthalmia, postaxial polydactyly, and developmental delay in the index patient to cleft uvula, growth delay, and mild developmental delay in her sister. The adults have a normal intelligence, postaxial polydactyly, and short stature or early cataract. Genotype-phenotype correlations suggest that the severity of eye manifestations in 14q22 deletions are influenced by the size of the deletion, but the marked intrafamilial variability observed in this family, as well as in familial BMP4 or OTX2 intragenic mutations points to additional modifiers outside this region., (Copyright © 2012 Wiley Periodicals, Inc.)

Recurrent rearrangements of chromosome 1q21.1 that occur via non-allelic homologous recombination have been associated with variable phenotypes exhibiting incomplete penetrance, including congenital heart disease (CHD). However, the gene or genes within the ~1 Mb critical region responsible for each of the associated phenotypes remains unknown. We examined the 1q21.1 locus in 948 patients with tetralogy of Fallot (TOF), 1488 patients with other forms of CHD and 6760 ethnically matched controls using single nucleotide polymorphism genotyping arrays (Illumina 660W and Affymetrix 6.0) and multiplex ligation-dependent probe amplification. We found that duplication of 1q21.1 was more common in cases of TOF than in controls [odds ratio (OR) 30.9, 95% confidence interval (CI) 8.9-107.6); P = 2.2 × 10(-7)], but deletion was not. In contrast, deletion of 1q21.1 was more common in cases of non-TOF CHD than in controls [OR 5.5 (95% CI 1.4-22.0); P = 0.04] while duplication was not. We also detected rare (n = 3) 100-200 kb duplications within the critical region of 1q21.1 in cases of TOF. These small duplications encompassed a single gene in common, GJA5, and were enriched in cases of TOF in comparison to controls [OR = 10.7 (95% CI 1.8-64.3), P = 0.01]. These findings show that duplication and deletion at chromosome 1q21.1 exhibit a degree of phenotypic specificity in CHD, and implicate GJA5 as the gene responsible for the CHD phenotypes observed with copy number imbalances at this locus.

The proximal region of the long arm of chromosome 22 is rich in low copy repeats (LCR). Non-allelic homologous recombination (NAHR) between these substrates explains the high prevalence of recurrent rearrangements within this region. We have performed array comparative genomic hybridization in a normally developing girl with growth delay, microcephaly, and truncus arteriosus, and have identified a novel recurrent 22q11 deletion that spans LCR22-4 and partially affects the common 22q11.2 deletion syndrome and the distal 22q11 deletion syndrome. This deletion is atypical as it did not occur by NAHR between any of the major LCRs found on 22q11.2. However, the breakpoint containing regions coincide with highly homologous regions. An identical imbalance was reported previously in a patient with striking phenotypic similarity. Computational gene prioritization methods and biological evidence denote the genes CRKL and MAPK1 as the highest ranking candidates for causing congenital heart disease within the deleted region., (Copyright © 2012 Wiley Periodicals, Inc.)

Purpose: The purpose of this study was to evaluate the clinical usefulness of the array comparative genomic hybridization technique for the genetic analysis of patients with congenital ocular malformations., Design: Laboratory investigation., Methods: This was a multicenter study. Samples were collected from 37 patients with negative results for the routine diagnostic work-up, including normal karyotype and mutation analysis of appropriate genes. Samples from both parents also were tested. High-resolution genome-wide Agilent 244K oligoarray (Agilent Technologies) was applied. Confirmation of the results was obtained with independent techniques., Results: Causal deletions were identified in 5 (13%) patients, affecting OTX2, FOXC1 and VPS13B (COH1), the downstream regulatory region of PAX6, and a 1,5 Megabases de novo deletion on chromosome 16., Conclusions: This high frequency of causal submicroscopic chromosomal aberrations in patients with congenital ocular malformation warrants implementation of array comparative genomic hybridization in the diagnostic work-up of these patients. Moreover, this screening technique broadens the phenotypic and mutational spectrum associated with genes known to cause congenital ocular malformation., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Introduction: The clinical phenotype of the chromosome 2q31 deletion syndrome consists of limb anomalies ranging from monodactylous ectrodactyly, brachydactyly and syndactyly to camptodactyly. Additional internal organ anomalies-for example, heart defects, ocular anomalies-may be present. Hemizygosity for HOXD13 and EVX2 genes was thought to cause the observed skeletal defects. Recently, based on the phenotype of patients with overlapping 2q31 interstitial deletions, a new SHFM5 locus was proposed, proximal to the HOXD cluster, between EVX2 and marker D2S294. DLX1 and DLX2 haploinsufficiency was suggested as the most plausible explanation for the observed SHFM-like limb anomalies in these cases., Methods and Results: Five unique, interstitial 2q31 deletion patients were selected to further characterise the 2q31 region and to establish a genotype/phenotype correlation map. The size of the deletions was delineated with a chromosome 2 specific tiling path bacterial artificial chromosome (BAC) array. The clinical and molecular data for this group of patients were compared to others in the literature. A common locus for the observed skeletal anomalies, including the HOXD genes and surrounding regulatory sequences, was delineated. These results correlate with recently published studies in animal models. In addition, a critical region for the facial gestalt of the 2q31.1 microdeletion syndrome was delineated., Conclusions: These results reinforce the hypothesis that the variable skeletal phenotype in 2q31 deletion patients is a result of hemizygosity for the HOXD genes and that the 2q31.1 microdeletion syndrome is a well defined and clinically recognisable phenotype.

Congenital heart defects (CHDs) are the most common major developmental anomalies and the most frequent cause for perinatal mortality, but their etiology remains often obscure. We identified a locus for CHDs on 6q24-q25. Genotype-phenotype correlations in 12 patients carrying a chromosomal deletion on 6q delineated a critical 850 kb region on 6q25.1 harboring five genes. Bioinformatics prioritization of candidate genes in this locus for a role in CHDs identified the TGF-beta-activated kinase 1/MAP3K7 binding protein 2 gene (TAB2) as the top-ranking candidate gene. A role for this candidate gene in cardiac development was further supported by its conserved expression in the developing human and zebrafish heart. Moreover, a critical, dosage-sensitive role during development was demonstrated by the cardiac defects observed upon titrated knockdown of tab2 expression in zebrafish embryos. To definitively confirm the role of this candidate gene in CHDs, we performed mutation analysis of TAB2 in 402 patients with a CHD, which revealed two evolutionarily conserved missense mutations. Finally, a balanced translocation was identified, cosegregating with familial CHD. Mapping of the breakpoints demonstrated that this translocation disrupts TAB2. Taken together, these data clearly demonstrate a role for TAB2 in human cardiac development., (Copyright 2010 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Subtelomeric rearrangements involving chromosome 6q have been reported in a limited number of studies. Although the sizes are very variable, ranging from cytogenetically visible deletions to small submicroscopic deletions, a common recognizable phenotype associated with a 6q deletion could be distilled. The main characteristics are intellectual disabilities, hypotonia, seizures, brain anomalies, and specific dysmorphic features including short neck, broad nose with bulbous tip, large and low-set ears and downturned corners of the mouth. In this article we report on a female patient, carrying a reciprocal balanced translocation t(5;6)(q23.1;q26), presenting with a clinical phenotype highly similar to the common 6q- phenotype. Breakpoint analysis using array painting revealed that the Quaking (QKI) gene that maps in 6q26 is disrupted, suggesting that haploinsufficiency of this gene plays a role in the 6q- clinical phenotype., (Copyright 2010 Wiley-Liss, Inc.)

We report on a patient with a microdeletion of chromosome region 9q22.32q31.1 including the PTCH1 gene (human homologue of the Drosophila patched 1 gene), review the findings in the reported patients with similar array CGH findings, and highlight the non nevoid basal cell carcinoma/non-Gorlin syndrome findings at an earlier age. These are macrocephaly, neonatal hypotonia, severe psychomotor retardation with markedly delayed motor milestones and speech development, epicanthic folds, a thin upper lip, a short and wide/webbed neck, pectus excavatum and (kypho)scoliosis. These features should alert the physician to an early diagnosis of the microdeletion and allow the initiation of essential clinical management hereof.

A microdeletion in chromosome 22q11.2 is one of the most frequent genetic syndromes. The phenotypic manifestations vary widely, which has led to its initial description as apparently different clinical entities, such as the velocardiofacial syndrome (VCFS) and DiGeorge syndrome. Characteristic features include cleft palate, conotruncal heart malformations, thymus hypoplasia, hypoparathyroidism, a characteristic facial phenotype and learning difficulties. Ocular abnormalities are frequently seen in this patient population. We describe the ophthalmological findings in 36 children between the age of 3 and 14 years with a microdeletion in chromosome 22q11.2. They underwent a full ophthalmological examination with assessment of visual acuity, eye position and motility, stereoscopic vision, biomicroscopic examination, refraction and fundoscopy. If necessary amblyopia treatment was started and follow-up was planned. The presence of a cardiovascular malformation was noted. In conclusion, refractive errors, strabismus, amblyopia and structural ocular abnormalities are frequently encountered in children with a microdeletion in chromosome 22q11.2. Ophthalmological examination at a young age and refractive correction in those children is warranted. On the other hand, ocular findings can give a clue to the diagnosis of del 22q11.2.

We report on a new-born girl with left ventricular non-compaction (LVNC), dysmorphism and epilepsy. Array-CGH at 1 Mb resolution revealed a deletion of the terminal 4.6 to 5.9 Mb of the short arm of chromosome 1. Cardiac abnormalities such as dilated cardiomyopathy and structural cardiac defects are common findings in patients with monosomy 1p36. This is however the first report describing LVNC in association with the 1p36 deletion syndrome, broadening the spectrum of cardiac anomalies found in association with this syndrome.

Holoprosencephaly (HPE) is the most common developmental field defect in patterning of the human prosencephalon and associated craniofacial structures. The genetics is complex, with 12 loci defined on 11 chromosomes. We defined a locus for HPE (HPE8) on human chromosome 14q13 between markers D14S49 and AFM205XG5, by mapping deletion intervals of affected subjects with proximal chromosome 14q interstitial cytogenetic deletions. A 35-BAC contig was built by chromosome walking. By annotation of the 2.82-Mb minimal critical region, we identified 28 possible genes. Seven genes were expressed in human fetal brain: NPAS3, SNX6, C14ORF11, C14ORF10, PAX9, NKX2.1, and C14ORF19, the last an apparent gene fragment. Molecular embryology, animal modeling, and human mutation studies were reported elsewhere for PAX9 and NKX2.1. We focused on three genes, SNX6, NPAS3, and C14ORF11, as potential candidates for HPE. Genomic structure, human expression patterns, protein cellular localization, and embryonic expression patterns of orthologous murine genes were determined, showing that the three genes have properties similar to those of known HPE genes.

Chromosome 10p terminal deletions have been associated with a DiGeorge like phenotype. Haploinsufficiency of the region 10p14-pter, results in hypoparathyroidism, sensorineural deafness, renal anomaly, that is the triad that features the HDR syndrome. Van Esch (2000) identified in a HDR patient, within a 200 kb critical region, the GATA3 gene, a transcription factor involved in the embryonic development of the parathyroids, auditory system and kidneys. We describe a new male patient, 33-year-old, with 10p partial deletion affected by hypocalcemia, basal ganglia calcifications and a severe autistic syndrome associated with mental retardation. Neurologically he presented severe impairment of language, hypotonia, clumsiness and a postural dystonic attitude. A peripheral involvement of auditory pathways was documented by auditory evoked potentials alterations. CT scan documented basal ganglia calcifications. Hyperintensity of the lentiform nuclei was evident at the MRI examination. Renal ultrasound scan was normal. Haploinsufficiency for GATA3 gene was documented with FISH analysis using cosmid clone 1.2. Phenotypic spectrum observed in del (10p) is more severe than the classical DGS spectrum. GATA3 has been found to regulate the development of serotoninergic neurons. A serotoninergic dysfunction may be linked with autism in this patient.

Fine mapping of deletion regions in autistic patients represents a valuable screening tool for identifying candidate genes for autism. A number of studies have ascertained associations between autism and terminal 2q deletion with the breakpoint within 2q37. Here we describe a 12-year-old female patient with terminal 2q37.3 cryptic deletion and autistic behaviour. Her clinical features included hypotonia and feeding difficulties during infancy, coarse face with notably prominent forehead, prominent eyebrows, broad flat nasal bridge and round cheeks, small hands and feet with bilateral brachymetaphalangism, proximal implantation of the thumbs and short toenails, mild mental retardation and autistic behaviour. Recorded autistic features included early lack of eye contact and, during infancy, little social interactions, propensity to be stereotypically busy and to get anxious. In order to more closely delineate the linkage region for autism within 2q37, the findings in this patient were combined to those in 2 previously reported siblings with a well documented 2q37.3 deletion, but without autistic disorder. The exact size of the deleted segment was determined by mapping the deleted region in each group with a series of specific BAC clones linearly ordered on the 2q37 region. The deletion in the autistic patient appeared to be larger [breakpoint flanked by more centromeric clones RP11-680016 (236.9 Mb) and 201F21 (237.4 Mb)] than in the non autistic siblings [more telomeric clones RP11-205L13 (237.8 Mb) and 346114 (238.2 Mb)], revealing a distance of maximum 1.3 Mb between the breakpoints. Accordingly, the extent of the candidate region for susceptibility genes for autism on distal 2q is reduced to maximum 1.3 Mb. Comparison with another well documented autistic patient from the literature results in the same conclusion. These findings represent thus a further step towards identifying genes predisposing to autism.

Hemizygous deletion of chromosome 22q11 (del22q11) causes thymic, parathyroid, craniofacial and life-threatening cardiovascular birth defects in 1 in 4,000 infants. The del22q11 syndrome is likely caused by haploinsufficiency of TBX1, but its variable expressivity indicates the involvement of additional modifiers. Here, we report that absence of the Vegf164 isoform caused birth defects in mice, reminiscent of those found in del22q11 patients. The close correlation of birth and vascular defects indicated that vascular dysgenesis may pathogenetically contribute to the birth defects. Vegf interacted with Tbx1, as Tbx1 expression was reduced in Vegf164-deficient embryos and knocked-down vegf levels enhanced the pharyngeal arch artery defects induced by tbx1 knockdown in zebrafish. Moreover, initial evidence suggested that a VEGF promoter haplotype was associated with an increased risk for cardiovascular birth defects in del22q11 individuals. These genetic data in mouse, fish and human indicate that VEGF is a modifier of cardiovascular birth defects in the del22q11 syndrome.

School-aged children with del22q11.2 tend to show a typical learning and neuropsychological profile, which is characterised by a VIQ-PIQ discrepancy (in favour of the VIQ) and significantly better scores for reading (decoding) and spelling compared to mathematics. To the best of our knowledge, there exists no systematic research on the pre-academic and early academic skills that might underpin these learning difficulties. The purpose of the current study was to investigate more systematically these pre-academic and early academic skills in borderline to normal intelligent (FSIQ > 70) children with del22q11.2 in the last year of kindergarten and first grade of primary school in Flanders. In the kindergarten group, meta-linguistic awareness and counting skills were examined. In the group of first graders, children were tested on reading, spelling and mathematics. Thirteen children (mean age: 6 years 4 months (SD = 0.84); 9 boys, 4 girls) participated in this study. In the present study, there were no differences in intelligence and academic outcomes between boys and girls, and no differences in IQ and academic achievement between children with cardiac defects or severe velopharyngeal insufficiency (VPI) and children without these deficits. With regard to pre-academic achievement in general, a characteristic profile with clearly better results for meta-linguistic awareness in comparison to counting skills was found, but this difference is not statistically significant. Concerning early academic achievement, children with del22q11.2, as a group, perform (despite their somewhat lower general intelligence) on average compared with their age-related peers. However, at an individual level--especially within the domain of counting skills and mathematics--there is a wide variability, with some children showing remarkable learning difficulties already at an early age.

Clinical and cytogenetical findings are reported and discussed on two siblings with discordant phenotypes despite having both a terminal 11q deletion and a distal 12q duplication resulting from an unbalanced segregation of a balanced translocation t(11:12)(q23:q24.1) mat. The oldest child, a girl, is the index patient. Her clinical features include intrauterine and postnatal growth retardation, fetal distress, mild hypotonia, early feeding difficulties, moderate developmental delay, especially in language acquisition, a velopharyngeal insufficiency with repeated otorhinopharyngeal infections, facial dysmorphism, heart ventricular septal defect, and abnormal hyperactive behaviour with sometimes autistic tendencies. The facial dysmorphic features notably consist of microcephaly, hypertelorism, large palpebral fissures, large eyes with alternant divergent strabismus, long eyelashes, a long and broad nasal bridge, a short "crested" nose with salient tip, a fishmouth with large spaces between teeth and flat palate, retrognathism, large ears and multiple dimples. The second affected child is a boy showing low birthweight, moderate developmental retardation with mainly no active language at 32 months, behaviour abnormalities with an autistic tendency, and no major physical anomalies apart from a slight facial hypotonia with often open mouth, dimples on the shoulders and right cryptorchidism. The authors stress the variable clinical expression of the chromosomal imbalance in this family resulting in low birthweight, developmental delay, abnormal behaviour, but different degrees of physical features and dysmorphism. The possible contribution of each of the two aneusomies to the phenotype is discussed.

Smith-Magenis syndrome (SMS) is a multiple congenital anomaly/mental retardation syndrome associated with behavioral abnormalities and sleep disturbance. Most patients have the same approximately 4 Mb interstitial genomic deletion within chromosome 17p11.2. To investigate the molecular bases of the SMS phenotype, we constructed BAC/PAC contigs covering the SMS common deletion interval and its syntenic region on mouse chromosome 11. Comparative genome analysis reveals the absence of all three approximately 200-kb SMS-REP low-copy repeats in the mouse and indicates that the evolution of SMS-REPs was accompanied by transposition of adjacent genes. Physical and genetic map comparisons in humans reveal reduced recombination in both sexes. Moreover, by examining the deleted regions in SMS patients with unusual-sized deletions, we refined the minimal Smith-Magenis critical region (SMCR) to an approximately 1.1-Mb genomic interval that is syntenic to an approxiamtely 1.0-Mb region in the mouse. Genes within the SMCR and its mouse syntenic region were identified by homology searches and by gene prediction programs, and their gene structures and expression profiles were characterized. In addition to 12 genes previously mapped, we identified 8 new genes and 10 predicted genes in the SMCR. In the mouse syntenic region of the human SMCR, 16 genes and 6 predicted genes were identified. The SMCR is highly conserved between humans and mice, including 19 genes with the same gene order and orientation. Our findings will facilitate both the identification of gene(s) responsible for the SMS phenotype and the engineering of an SMS mouse model.

Children with a 22q11 deletion versus children with a speech-language impairment and learning disability: behavior during primary school age: Common behavioral features described in children with the Velo-Cardio-Facial syndrome (VCFS) (del 22q11) are problems with attention and concentration, extremes in behavior and social problems, especially in relationship with peers. At present, it is unclear whether these behavioral manifestations are directly related to the chromosomal anomaly or related to other manifestations of the syndrome such as developmental delay and speech-language delay. This study describes for the first time the behavior of young primary school aged children with a del22q11 compared to a control group of children matched for age, sex and mental level, with similar developmental problems (speech-language impairment plus learning disability: SLI + LD) but without a del22q11 or any other known genetic condition. Parents and teachers evaluated the children's behavior with standardized questionnaires (CBCL; TRF). Results indicate that most of the behaviors are similar across both groups. The only differences found are in the field of <> and <>. Children with a del22q11 have a stronger tendency to withdraw from others, whereas children with a SLI+LD seem to be more aggressive.

Aneurysm of the ductus arteriosus is a rare abnormality for which different ways of pathogenesis are described. We report the case of a fatal thrombosis of an aneurysm of the ductus arteriosus in an infant presenting feeding difficulties and a mild dysmorphic facies. Karyotype analysis revealed a de novo chromosomal deletion 46,XY, del (13)(q12.3,q22.3). To the best of our knowledge, this is the first case of an aneurysm of the ductus arteriosus associated with a chromosomal aberration.

The velo-cardio-facial syndrome (VCFS) is a leading cause of velopharyngeal dysfunction and cleft palate and caused by a submicroscopic deletion in the long arm of chromosome 22 (band 22q11). During the last 5 years, 130 patients with a 22q11 deletion were diagnosed in Leuven. Most patients presented a wide variety of the classical features of the velo-cardio-facial syndrome. Velopharyngeal dysfunction was almost always present whereas an isolated cleft lip/palate was observed in a minority of patients. The velopharyngeal function can be evaluated by the classic combination of indirect and direct techniques. Because of the frequent occurrence of the velo-cardio-facial syndrome, estimated at around 1/4000 live births, and given the extremely broad clinical spectrum which makes clinical diagnosis difficult, screening of patients with velopharyngeal dysfunction for a deletion 22q11 is indicated.

In this contribution we review current knowledge of the chromosome 22q11 deletion syndrome, with special emphasis on the clinical characteristics, including physical features, cognitive-behavioral spectrum, and psychiatric complications.

In this exploratory study, the neuropsychological and learning profile of nine primary school age children with velo-cardio-facial syndrome (VCFS) was studied by systematic neuropsychological testing. In five out of nine children, the following profile was found: a VIQ-PIQ discrepancy (in favor of the VIQ), significantly better scores (.05 level) for reading (decoding) and spelling compared to arithmetic, deficient tactile-perceptual skills (difficulties mainly on the left side of the body), weak but not deficient visual-perceptual abilities, deficient visual-spatial skills, extremely poor psychomotor skills (gross motor skills more deficient than fine motor skills), problems with processing of new and complex material, poor visual attention, good auditory memory and relatively good language skills. These findings correspond to the pattern of neuropsychological assets and deficits that has been described for the syndrome of nonverbal learning disabilities (NLD) (Rourke, 1987, 1988, 1989, 1995). The psychosocial profile of all nine children with VCFS also correspond to that of children with NLD. Further studies on the relationship between cognitive function, behavior, psychiatric disorder and abnormalities in brain anatomy in young people with VCFS will be needed. In clinical practice, it is worthwhile exploring in greater depth the neuropsychological functions of children with VCFS to rule out NLD, since they may benefit from specific remediation following the learning principles of the NLD-treatment.

Deletions in the distal region of chromosome 8p (del8p) are associated with congenital heart malformations. Other major manifestations include microcephaly, intrauterine growth retardation, mental retardation, and a characteristic hyperactive, impulsive behavior. We studied genotype-phenotype correlations in nine unrelated patients with a de novo del8p, by using the combination of classic cytogenetics, FISH, and the analysis of polymorphic DNA markers. With the exception of one large terminal deletion, all deletions were interstitial. In five patients, a commonly deleted region of approximately 6 Mb was present, with breakpoints clustering in the same regions. One patient without a heart defect or microcephaly but with mild mental retardation and characteristic behavior had a smaller deletion within this commonly deleted region. Two patients without a heart defect had a more proximal interstitial deletion that did not overlap with the commonly deleted region. Taken together, these data allowed us to define the critical deletion regions for the major features of a del8p.

A child with monosomy for the distal part of the short arm of chromosome 3 (3p25-->pter) and trisomy for the terminal portion of the long arm of chromosome 17 (17q23-->qter) is presented. This unbalanced karyotype was derived from a balanced reciprocal 3p/17q translocation in the phenotypically normal mother. Main clinical features in the proband included growth and mental retardation, hypotonia, hirsutism, micro/brachycephaly, triangular face, synophris, broad and full nose, long philtrum, narrow upper lip, low set, posteriorly turned ears, anteriorly placed anus and congenital heart defect (Tetralogy of Fallot). Most of these clinical manifestations have been constantly reported in previous cases with terminal 3p deletion.

We report data on feeding and speech disorders in 50 patients with velocardiofacial syndrome. In order to contribute to delineation of type and etiology of feeding and speech problems, we compared the clinical findings in these patients with the reports in literature.

During the last 5 years, we diagnosed in Leuven 130 patients with a 22q11 deletion. The deletion was familial in 14 out of 110 index patients (12%), which is significantly less compared to previous studies. In 10 patients, the deletion was maternal, in 4 patients paternal. A cardiac defect was the main presenting symptom in 49% of patients. The other patients were ascertained through developmental delay (16%), behavioural disturbances (7%), otorhinolaryngological manifestations (6%), psychiatric manifestations (3%) and mental retardation (2%). In one patient hypocalcemia was the presenting symptom. In another patient the severe immune deficiency led to diagnosis. Most patients presented a wide variety of the classical features of the Velo-Cardio-Facial syndrome. Velopharyngeal incompetence, learning difficulties or mostly mild mental retardation were almost always present, whereas clinical significant hypocalcemia or immune disturbances were rare. Previously un(der)recognised features include polyhydramnios, renal malformations and laryngotracheamalacia or laryngeal stenosis.

In this contribution the current status and recent findings of the behavioural phenotype in VCFS (22q11 deletion) are discussed with regard to motor development, cognition and neurodevelopment, and behaviour and temperament. Motor: hypotonia in infancy, gross-motor milestones are delayed, problems with coordination and balance from preschool age on, problems with tempo/speed during adolescence. Cognition and neurodevelopment: learning disabilities (82-100%), intellectual disability (45%), better verbal abilities than performal abilities, poor attention and concentration, visuo-perceptual-spatia problems, good (auditory) memory. An important subgroup of children (55%) has a non-verbal learning disability (NLD). Behaviour and social-emotional development AD(H)D, withdrawn and shy, person-dependent social problems in relationships with peers, anxious, risk for child psychiatric problems as well as for the development of psychiatric problems during adolescence and early adulthood. Information on the behavioural phenotype in VCFS (22q11 deletion) is of great importance to clinicians as an aid to syndrome diagnosis, but even more to parents because it offers immense direct practical value to the management of the behaviour of their child. Appropriate counseling and information on the long-term expectations, and better insight in the behaviour will lead to the development of realistic ways of coping with their child.

We reviewed 36 patients with a deletion of the short arm of chromosome 10 and a partial DiGeorge syndrome. We compared the phenotypes observed in these del(10p) patients with the classical DiGeorge phenotype associated with del(22q11), pointing out both similarities and differences. Some features, such as sensorineural hearing loss, seem to be highly associated with a deletion of 10p but are absent in the classical DiGeorge spectrum caused by del(22q11).

The velo-cardio-facial syndrome (VCFS), due to a deletion in chromosome 22 on its long arm (22q11), is a leading cause of velopharyngeal dysfunction and cleft palate. With the recent finding of a deletion on chromosome 22q11 in these patients with velopharyngeal dysfunction, a routine test is available making the diagnosis of VCFS much more frequent than previously thought.

Patients with a microdeletion on chromosome 22q11 demonstrate the clinical picture of the velocardiofacial syndrome. We report on three members of the same family with this microdeletion and velocardiofacial syndrome, all having an increase in platelet size and a mild decrease in platelet number. Their platelet function, however, tested by aggregation and by adherence to collagen in a whole blood perfusion system, was normal. We retrospectively studied the files of 35 other patients with 22q11 deletion and also found that their platelets had an increased size compared with cardiac controls. Moreover, their platelet size correlated negatively with platelet number. Knowing that patients with 22q11 deletion are obligate carriers for a heterozygous glycoprotein Ib beta deletion, these patients can be considered to be heterozygous Bernard-Soulier patients. In addition, a significant increase in platelet size may be a positive predictor for the clinical diagnosis of the velocardiofacial syndrome.

We present a female child with features of the CHARGE association, including iris coloboma, large ventricular septum defect (VSD), external ear abnormalities, severe growth retardation and moderate mental delay. A submicroscopic deletion in chromsome 22q11 was detected by means of fluorescence in situ hybridization (FISH) using probe DO832. The clinical features in this child compromise characteristics of both the velo-cardio-facial syndrome (VCFS) and the cat-eye syndrome. This may suggest the presence of a more complex rearrangement of 22q, with a deletion-duplication.

We present genotype-phenotype correlations in two patients with distal 10q deletion. A patient with a small terminal deletion presented mild mental retardation and behavioral difficulties with hyperactivity, whereas the patient with a larger deletion, had multiple congenital anomalies and moderate mental retardation. Our observation confirms the previous suggestion that larger deletions of distal chromosome 10q are associated with a more severe clinical presentation, whereas hyperactive behavior may be a specific feature of small terminal deletions of chromosome 10q26.