Structural deviations of the posterior fossa and the cerebellum and their cognitive links in a neurodevelopmental deletion syndrome

High-impact genetic variants associated with neurodevelopmental disorders provide biologically-defined entry points for mechanistic investigation. The 3q29 deletion (3q29Del) is one such variant, conferring a 40-100-fold increased risk for schizophrenia, as well as high risk for autism and intellectual disability. However, the mechanisms leading to neurodevelopmental disability remain largely unknown. Here, we report the first in vivo quantitative neuroimaging study in individuals with 3q29Del (N = 24) and neurotypical controls (N = 1608) using structural MRI. Given prior radiology reports of posterior fossa abnormalities in 3q29Del, we focused our investigation on the cerebellum and its tissue-types and lobules. Additionally, we compared the prevalence of cystic/cyst-like malformations of the posterior fossa between 3q29Del and controls and examined the association between neuroanatomical findings and quantitative traits to probe gene-brain-behavior relationships. 3q29Del participants had smaller cerebellar cortex volumes than controls, before and after correction for intracranial volume (ICV). An anterior-posterior gradient emerged in finer grained lobule-based and voxel-wise analyses. 3q29Del participants also had larger cerebellar white matter volumes than controls following ICV-correction and displayed elevated rates of posterior fossa arachnoid cysts and mega cisterna magna findings independent of cerebellar volume. Cerebellar white matter and subregional gray matter volumes were associated with visual-perception and visual-motor integration skills as well as IQ, while cystic/cyst-like malformations yielded no behavioral link. In summary, we find that abnormal development of cerebellar structures may represent neuroimaging-based biomarkers of cognitive and sensorimotor function in 3q29Del, adding to the growing evidence identifying cerebellar pathology as an intersection point between syndromic and idiopathic forms of neurodevelopmental disabilities.

Behavioral Phenotypes and Comorbidity in 3q29 Deletion Syndrome: Results from the 3q29 Registry

3q29 deletion syndrome (3q29del) is associated with a significantly increased risk for neurodevelopmental and neuropsychiatric disorders. However, the full spectrum of behavioral phenotypes associated with 3q29del is still evolving. Individuals with 3q29del (n = 96, 60.42% male) or their guardian completed the Achenbach Child or Adult Behavior Checklist (CBCL/ABCL) via the online 3q29 registry (3q29deletion.org). Typically developing controls (n = 57, 49.12% male) were ascertained as a comparison group. We analyzed mean performance on the CBCL/ABCL for individuals with 3q29del and controls across composite, DSM-keyed, and developmental scales; and the relationship between CBCL/ABCL performance and clinical and developmental phenotypes for individuals with 3q29del. Individuals with 3q29del showed significantly elevated behavioral and developmental impairment relative to controls across CBCL/ABCL domains. A substantial proportion of study participants with 3q29del scored in the Borderline or Clinical range for composite and DSM-keyed scales, indicating significant behavioral problems that may require clinical evaluation. We found that the preschool CBCL DSM-keyed autism spectrum problems scale is a potential screening tool for autism spectrum disorder (ASD) for individuals with 3q29del; CBCL/ABCL DSM-keyed scales were not accurate screeners for anxiety disorders or attention-deficit/hyperactivity disorder (ADHD) in our study sample. We identified a high degree of psychiatric comorbidity in individuals with 3q29del, with 60.42% (n = 58) of individuals with 3q29del scoring in the Borderline or Clinical range on two or more DSM-keyed CBCL/ABCL scales. Finally, we found that the degree of developmental delay in participants with 3q29del does not explain the increased behavioral problems observed on the CBCL/ABCL. The CBCL/ABCL can be used as screening tools in populations such as 3q29del, even in the presence of substantial psychiatric comorbidity. These results expand our understanding of the phenotypic spectrum of 3q29del and demonstrate an effective method for recruiting and phenotyping a large sample of individuals with a rare genetic disorder.

Genetic diagnostic yields of 354 Chinese ASD children with rare mutations by a pipeline of genomic tests

Purpose: To establish an effective genomic diagnosis pipeline for children with autism spectrum disorder (ASD) for its genetic etiology and intervention. Methods: A cohort of 354 autism spectrum disorder patients were obtained from Beijing Children's Hospital, Capital Medical University. Peripheral blood samples of the patients were collected for whole genome sequencing (WGS) and RNA sequencing (RNAseq). Sequencing data analyses were performed for mining the single nucleotide variation (SNV), copy number variation (CNV) and structural variation (SV). Sanger sequencing and quantitative PCR were used to verify the positive results. Results: Among 354 patients, 9 cases with pathogenic/likely pathogenic copy number variation and 10 cases with pathogenic/likely pathogenic single nucleotide variations were detected, with a total positive rate of 5.3%. Among these 9 copy number variation cases, 5 were de novo and 4 were inherited. Among the 10 de novo single nucleotide variations, 7 were previously unreported. The pathological de novo mutations account for 4.2% in our cohort. Conclusion: Rare mutations of copy number variations and single nucleotide variations account for a relatively small proportion of autism spectrum disorder children, which can be easily detected by a genomic testing pipeline of combined whole genome sequencing and RNA sequencing. This is important for early etiological diagnosis and precise management of autism spectrum disorder with rare mutations.

Autism spectrum disorder symptom expression in individuals with 3q29 deletion syndrome

BACKGROUND

The 1.6 Mb 3q29 deletion is associated with neurodevelopmental and neuropsychiatric phenotypes, including a 19-fold increased risk for autism spectrum disorder (ASD). Previous work by our team identified elevated social disability in this population via parent-report questionnaires. However, clinical features of ASD in this population have not been explored in detail.

METHODS

Thirty-one individuals with 3q29 deletion syndrome (3q29del, 61.3% male) were evaluated using two gold-standard clinical ASD evaluations: the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2), and the Autism Diagnostic Interview, Revised (ADI-R). Four matched comparators for each subject were ascertained from the National Database for Autism Research. Item-level scores on the ADOS-2 and ADI-R were compared between subjects with 3q29del and matched comparators.

RESULTS

Subjects with 3q29del and no ASD (3q29del-ASD) had greater evidence of social disability compared to typically developing (TD) comparison subjects across the ADOS-2. Subjects with 3q29del and ASD (3q29del + ASD) were largely indistinguishable from non-syndromic ASD (nsASD) subjects on the ADOS-2. 3q29del + ASD performed significantly better on social communication on the ADI-R than nsASD (3q29 + ASD mean = 11.36; nsASD mean = 15.70; p = 0.01), and this was driven by reduced deficits in nonverbal communication (3q29 + ASD mean = 1.73; nsASD mean = 3.63; p = 0.03). 3q29del + ASD reported significantly later age at the first two-word phrase compared to nsASD (3q29del + ASD mean = 43.89 months; nsASD mean = 37.86 months; p = 0.01). However, speech delay was not related to improved nonverbal communication in 3q29del + ASD.

LIMITATIONS

There were not enough TD comparators with ADI-R data in NDAR to include in the present analysis. Additionally, our relatively small sample size made it difficult to assess race and ethnicity effects.

CONCLUSIONS

3q29del is associated with significant social disability, irrespective of ASD diagnosis. 3q29del + ASD have similar levels of social disability to nsASD, while 3q29del-ASD have significantly increased social disability compared to TD individuals. However, social communication is reasonably well preserved in 3q29del + ASD relative to nsASD. It is critical that verbal ability and social disability be examined separately in this population to ensure equal access to ASD and social skills evaluations and services.

A family study of symbolic learning and synaptic plasticity in autism spectrum disorder

The current study presents a male with autism spectrum disorder (ASD) and a 3q29 deletion, and three healthy first-degree relatives. Our magnetic resonance imaging (MRI) dataset included a healthy control subset. We describe a comprehensive multimodal approach, including equivalence class formation, neurocognitive testing, MRI, and electroencephalography (EEG)-based cortical plasticity, which can provide new insights into socio-communicative and learning impairments and neural underpinnings in ASD. On neurocognitive testing, the proband showed reduced processing speed, attending behavior, and executive function. He required more training trials in equivalence class training compared with family members and exhibited impaired priming of words compared with priming with images. The proband had smaller intracranial volume and surface area and a larger visual evoked potential (VEP) C1 amplitude than family members and intact long-term potentiation (LTP)-like visual cortex plasticity. Together, these results suggest that 3q29 deletion-related ASD is associated with impaired problem-solving strategies in complex socio-communicative and learning tasks, smaller intracranial and surface area, altered VEP amplitude, and normal LTP-like visual cortex plasticity. Further studies are needed to clarify whether this multimodal approach can be used to identify ASD subgroups with distinct neurobiological alterations and to uncover mechanisms underlying socio-communicative and learning impairments. Lay Summary: We studied learning, brain activity, and brain structure in a person with autism and a genetic aberration, and his close relatives. Compared with relatives, the person with autism required more training for learning, and visual learning was better than verbal learning. This person had some changes in the activity of the visual cortex, and the size and the surface area of the brain were reduced. Knowledge about learning and brain mechanisms is valuable for the development of training programs for individuals with autism.

Prenatal detection of a 3q29 microdeletion in a fetus with ventricular septum defect: A case report and literature review

RATIONALE

Chromosomal 3q deletion is a recurrent genomic alternation, which is rarely reported in clinic.

PATIENT CONCERNS

A 27-year-old woman underwent amniocentesis for cytogenetic analysis and single nucleotide polymorphism (SNP) array analysis at 27 weeks of gestation, due to ventricular septum defect in prenatal ultrasound findings.

DIAGNOSES

G-banding analysis showed the karyotype of the fetus was normal and the couple also had normal karyotypes. However, SNP array detected a 1.71 Mb microdelection in 3q29, which was described as arr[hg19]3q29(194184392-195887205) × 1. There are 12 genes located in this locus.

INTERVENTIONS

The couple refused SNP array to testify the 3q29 microdeletion was inherited or de novo and they chose termination of pregnancy.

OUTCOMES

The deleted region in the fetus overlapped with part 3q29 microdeletion syndrome, which was characterized by learning disability, speech delay, mental deficiency, ocular abnormalities and craniofacial features. In addition, no similar/overlapping 3q29 microdeletion cases were reported according to the published literature and database.

LESSONS

For the chromosomal microscopic imbalances partially overlapping with the defined pathogenic syndrome, deleted/duplicated size, genetic materials and phenotypic diversity should be taken into consideration when genetic counseling is offered by the clinicians.

Comprehensive phenotyping of neuropsychiatric traits in a multiplex 3q29 deletion family: a case report

BACKGROUND

3q29 deletion syndrome is associated with a range of medical, neurodevelopmental, and psychiatric phenotypes. The deletion is usually de novo but cases have been reported where the deletion is inherited from apparently unaffected parents. The presence of these unaffected or mildly affected individuals suggests there may be an ascertainment bias for severely affected cases of 3q29 deletion syndrome, thus the more deleterious consequence of the 3q29 deletion may be overestimated. However, a substantial fraction of 3q29 deletion syndrome morbidity is due to psychiatric illness. In many case reports, probands and transmitting parents are not systematically evaluated for psychiatric traits. Here we report results from a systematic phenotyping protocol for neurodevelopmental and neuropsychiatric traits applied to all 3q29 deletion carriers in a multiplex family.

CASE PRESENTATION

Through the 3q29 registry at Emory University, a multiplex family was identified where three offspring had a paternally inherited 3q29 deletion. We evaluated all 4 3q29 deletion family members using our previously described standardized, systematic phenotyping protocol. The transmitting parent reported no psychiatric history, however upon evaluation he was discovered to meet criteria for multiple psychiatric diagnoses including previously undiagnosed schizoaffective disorder. All four 3q29 deletion individuals in the pedigree had multiple psychiatric diagnoses that interfered with quality of life and prohibited successful academic and occupational functioning. Cognitive ability for all individuals was average or below average, but within the normal range.

CONCLUSIONS

This is the first case report of inherited 3q29 deletion syndrome where all affected individuals in the pedigree have been comprehensively and systematically evaluated for neurodevelopmental and psychiatric symptoms, using a standard battery of normed instruments administered by expert clinicians. Our investigation reveals that individuals with 3q29 deletion syndrome may have psychiatric morbidity that is debilitating, but only apparent through specialized evaluation by an expert. In the absence of appropriate evaluation, individuals with 3q29 deletion syndrome may suffer from psychiatric illness but lack avenues for access to care. The individuals evaluated here all have cognition in the normal range alongside multiple psychiatric diagnoses each, suggesting that cognitive ability alone is not a representative proxy for 3q29 deletion-associated disability. These results require replication in a larger cohort of individuals with 3q29 deletion syndrome.

Neuropsychiatric phenotype in relation to gene variants in the hemizygous allele in 3q29 deletion carriers: A case series

Background

Genetic risk variants in the hemizygous allele may influence neuropsychiatric manifestations and clinical course in 3q29 deletion carriers.

Methods

In‐depth phenotypic assessment in two deletion carriers included medical records, medical, genetic, psychiatric and neuropsychological evaluations, brain MRI scan and EEG. Blood samples were analyzed for copy number variations, and deep sequencing of the affected 3q29 region was performed in patients and seven first‐degree relatives. Risk variants were identified through bioinformatic analysis.

Results

One deletion carrier was diagnosed with learning difficulties and childhood autism, the other with mild intellectual disability and schizophrenia. EEG abnormalities in childhood normalized in adulthood in both. Cognitive abilities improved during adolescence in one deletion carrier. Both had microcytic, hypochromic erythrocytes and suffered from chronic pain and fatigue. Molecular and bioinformatic analyses identified risk variants in the hemizygous allele that were not present in the homozygous state in relatives in genes involved in cilia function and insulin action in the autistic individual and in synaptic function and neurosteroid transport in the subject with schizophrenia.

Conclusion

3q29 deletion carriers may undergo developmental phenotypic transition and need regular medical follow‐up. Identified risk variants in the remaining hemizygous allele should be explored further in autism and schizophrenia research.

Neuropsychiatric phenotypes and a distinct constellation of ASD features in 3q29 deletion syndrome: results from the 3q29 registry

Background

The 1.6 Mb 3q29 deletion is associated with neurodevelopmental and psychiatric phenotypes, including increased risk for autism spectrum disorder (ASD) and a 20 to 40-fold increased risk for schizophrenia. However, the phenotypic spectrum of the deletion, particularly with respect to ASD, remains poorly described.

Methods

We ascertained individuals with 3q29 deletion syndrome (3q29Del, “cases,” n = 93, 58.1% male) and typically developing controls (n = 64, 51.6% male) through the 3q29 registry (https://3q29deletion.patientcrossroads.org). Self-report of neuropsychiatric illness was evaluated for 93 cases. Subsets of participants were evaluated with the Social Responsiveness Scale (SRS, n = 48 cases, 56 controls), Social Communication Questionnaire (n = 33 cases, 46 controls), Autism Spectrum Screening Questionnaire (n = 24 cases, 35 controls), and Achenbach Behavior Checklists (n = 48 cases, 57 controls).

Results

3q29Del cases report a higher prevalence of autism diagnoses versus the general population (29.0% vs. 1.47%, p < 2.2E− 16). Notably, 3q29 deletion confers a greater influence on risk for ASD in females (OR = 41.8, p = 4.78E− 05) than in males (OR = 24.6, p = 6.06E− 09); this is aligned with the reduced male:female bias from 4:1 in the general population to 2:1 in our study sample. Although 71% of cases do not report a diagnosis of ASD, there is evidence of significant social disability (3q29Del SRS T-score = 71.8, control SRS T-score = 45.9, p = 2.16E− 13). Cases also report increased frequency of generalized anxiety disorder compared to controls (28.0% vs. 6.2%, p = 0.001), which is mirrored by elevated mean scores on the Achenbach diagnostic and statistical manual-oriented sub-scales (p < 0.001). Finally, cases show a distinct constellation of ASD features on the SRS as compared to idiopathic ASD, with substantially elevated Restricted Interests and Repetitive Behaviors, but only mild impairment in Social Motivation.

Conclusions

Our sample of 3q29Del is significantly enriched for ASD diagnosis, especially among females, and features of autism may be present even when an ASD diagnosis is not reported. Further, the constellation of ASD features in this population is distinct from idiopathic ASD, with substantially less impaired social motivation. Our study implies that ASD evaluation should be the standard of care for individuals with 3q29Del. From a research perspective, the distinct ASD subtype present in 3q29Del is an ideal entry point for expanding understanding of ASD.

Electronic supplementary material

The online version of this article (10.1186/s13229-019-0281-5) contains supplementary material, which is available to authorized users.

A Novel 3q29 Deletion in Association With Developmental Delay and Heart Malformation-Case Report With Literature Review

3q29 deletion syndrome is a rare disorder, causing a complex phenotype. Clinical features are variable and relatively non-specific. Our report aims to present an atypical, de novo deletion in chromosome band 3q29 in a preschool boy, first child of healthy non-consanguineous parents, presenting a particular phenotype (microcephaly, "full moon" face, flattened facial profile, large ears, auricular polyp, and dental dystrophies), motor and cognitive delay, characteristics of autism spectrum disorder and aggressive behavior. He also presented intrauterine growth restriction (birth weight 2,400 g) and a ventricular septal defect. SNP Array revealed a 962 kb copy number loss, on the chromosome 3q29 band (195519857-196482211), consistent with 3q29 microdeletion syndrome. FISH analysis using a RP11-252K11 probe confirmed the deletion in the proband, which was not present in the parents. Although the patient's deletion is relatively small, it partly overlaps the canonical 3q29 deletion (defined between TFRC and DLG1 gene) and extends upstream, associating a different facial phenotype compared to the classic 3q29 deletion, nonetheless showing a similar psychiatric disorder. This deletion is different from the canonical region, as it does not include the PAK2 and DLG1 genes, considered as candidates for causing intellectual disability. Thus, narrowing the genotype-phenotype correlation for the 3q29 band, FBX045 is suggested as a candidate gene for the neuropsychiatric phenotype.

Copy number variation in fetal alcohol spectrum disorder

Fetal alcohol spectrum disorder (FASD) is characterized by a combination of neurological, developmental, and congenital defects that may occur as a consequence of prenatal alcohol exposure. Earlier reports showed that large chromosomal anomalies may link to FASD. Here, we examined the prevalence and types of copy number variations (CNVs) in FASD cases previously diagnosed by a multidisciplinary FASD team in sites across Canada. We genotyped 95 children with FASD and 87 age-matched, typically developing controls on the Illumina Human Omni2.5 SNP (single nucleotide polymorphisms) array platform. We compared their CNVs with those of 10 851 population controls to identify rare CNVs (<0.1% frequency), which may include large unbalanced chromosomal abnormalities, that might be relevant to FASD. In 12/95 (13%) of the FASD cases, rare CNVs were found that impact potentially clinically relevant developmental genes, including the CACNA1H involved in epilepsy and autism, the 3q29 deletion disorder, and others. Our results show that a subset of children diagnosed with FASD have chromosomal deletions and duplications that may co-occur or explain the neurodevelopmental impairments in a diagnosed cohort of FASD individuals. Children suspected to have FASD with or without sentinel facial features of fetal alcohol syndrome and neurodevelopmental delays should potentially be evaluated by a clinical geneticist and possibly have genetic investigations as appropriate to exclude other etiologies.

Novel 3q27.2-qter deletion in a patient with Diamond-Blackfan anemia and immunodeficiency: Case report and review of literature

3q27.2-qter deletion syndromes feature an overlapping set of terminal and interstitial deletions with variable congenital malformations. Diamond-Blackfan anemia (DBA) is etiologically heterogeneous disorder in which one cause is dominant mutations of the RPL35A gene on 3q29. We report a child with a 3q27.2-qter deletion that contains the RPL35A gene. She had clinical and laboratory features consistent with DBA and as well, an unexplained immunodeficiency disorder. Given these unusual findings, we reviewed other patients in the literature with overlapping genomic deletions. In addition, we evaluated our patient for the immunodeficiency disorder, RIDDLE syndrome, due to recessive mutations in the RNF168 gene on 3q29. A PubMed search for case reports of 3q27.2-qter overlapping deletions was performed. To determine if RPL35A was in the deletion region, the chromosomal regions reported were mapped to genomic regions using the UCSC Genome Browser. We identified 85 overlapping deletions, of which six included the RPL35A gene and all should be had DBA. Interestingly, none of the reported cases had immunodeficiency. To evaluate RIDDLE syndrome (radiosensitivity, immunodeficiency, dysmorphic features, and learning difficulties), we sequenced the remaining RNF168 gene and examined her fibroblast culture for a DNA double strand break repair deficiency. These results were normal, indicating that the immunodeficiency is unlikely to result from a RNF168 deficiency. We show that RPL35A haploinsufficiency is a cause of DBA and we report a novel case with 3q27.2-qter deletion and immunodeficiency. The etiology for the immunodeficiency remains unsolved and could be caused by an unknown gene effect or consequent to the DBA phenotype.

A clinical case report and literature review of the 3q29 microdeletion syndrome

We report on a 15-year-old male with the 3q29 microdeletion syndrome and summarize the medical literature. He had intellectual disability, autism spectrum disorder, anxiety, obsessive compulsive tendencies, speech delay, delayed walking, a hypernasal voice, gait abnormalities, chronic constipation, gastroesophageal reflux disorder, urinary voiding dysfunction, abnormal skin pigmentation, and dysmorphic features. We present a review of the literature for the 3q29 microdeletion syndrome by comparing both the phenotype and the genetic defects in reported cases. Of the 38 previously reported cases with deletion size information, the most common chromosome deletion was 1.6 Mb in size including ∼ 30 genes. This emerging microdeletion syndrome is characterized by intellectual disability, speech delay, behavioral problems, craniofacial dysmorphism, and musculoskeletal abnormalities.

Contribution of genomic copy-number variations in prenatal oral clefts: a multicenter cohort study

PURPOSE

We sought to investigate the utility of chromosomal microarray analysis (CMA) for prenatal diagnosis of oral clefts, as compared with traditional chromosome analysis, for improved prenatal genetic counseling and discovery of a potential correlation between genotype and oral cleft.

METHODS

This retrospective analysis encompassed 270 prenatal oral cleft cases with documented detailed ultrasound findings and CMA results from four referral centers. Detection rates for pathogenic copy-number variants (CNVs) were calculated and compared with cases for which chromosome analysis was also performed.

RESULTS

The overall detection rate was 14.8% (40/270) for pathogenic CNVs by CMA, 7.2% (9/125) for the nonsyndromic cases, and 21.4% (31/145) for the syndromic cases. Of the nonsyndromic cases with ultrasound soft markers, 20% (5/25) were identified with pathogenic CNVs. CMA showed an improved detection rate of 15.3% (29/190) compared with 10.5% (20/190) for chromosome analysis.

CONCLUSION

This study not only highlights the improved detection of chromosomal defects by CMA in prenatal oral clefts but also deepens our understanding of oral clefts. The results suggest that CMA is highly recommended in prenatal invasive genetic testing not only for syndromic oral cleft cases but also for nonsyndromic cases with soft markers. Candidate genes including CRKL, AKAP8, SYDE1, BRD4 are worthy of further investigation regarding their role in human palatogenesis.Genet Med 18 10, 1052-1055.

Novel features of 3q29 deletion syndrome: Results from the 3q29 registry

3q29 deletion syndrome is caused by a recurrent, typically de novo heterozygous 1.6 Mb deletion, but because incidence of the deletion is rare (1 in 30,000 births) the phenotype is not well described. To characterize the range of phenotypic manifestations associated with 3q29 deletion syndrome, we have developed an online registry (3q29deletion.org) for ascertainment of study subjects and phenotypic data collection via Internet‐based survey instruments. We report here on data collected during the first 18 months of registry operation, from 44 patients. This is the largest cohort of 3q29 deletion carriers ever assembled and surveyed in a systematic way. Our data reveal that 28% of registry participants report neuropsychiatric phenotypes, including anxiety disorder, panic attacks, depression, bipolar disorder, and schizophrenia. Other novel findings include a high prevalence (64%) of feeding problems in infancy and reduced weight at birth for 3q29 deletion carriers (average reduction 13.9 oz (394 g), adjusted for gestational age and sex, P = 6.5e‐07). We further report on the frequency of heart defects, autism, recurrent ear infections, gastrointestinal phenotypes, and dental phenotypes, among others. We also report on the expected timing of delayed developmental milestones. This is the most comprehensive description of the 3q29 deletion phenotype to date. These results are clinically actionable toward improving patient care for 3q29 deletion carriers, and can guide the expectations of physicians and parents. These data also demonstrate the value of patient‐reported outcomes to reveal the full phenotypic spectrum of rare genomic disorders. © 2016 The Authors. American Journal of Medical Genetics Part A Published by Wiley Periodicals, Inc.

Congenital thrombocytopenia in a neonate with an interstitial microdeletion of 3q26.2q26.31

Interstitial deletions encompassing the 3q26.2 region are rare. Only one case-report was published this far describing a patient with an interstitial deletion of 3q26.2 (involving the MDS1-EVI1 complex (MECOM)) and congenital thrombocytopenia. In this report we describe a case of a neonate with congenital thrombocytopenia and a constitutional 4.52 Mb deletion of 3q26.2q26.31 including TERC and the first 2 exons of MECOM, involving MDS1 but not EVI1. The deletion was demonstrated by array-CGH on lymphocytes. Our report confirms that congenital thrombocytopenia can be due to a constitutional deletion of 3q26.2 involving MECOM. We suggest that in case of unexplained neonatal thrombocytopenia, with even just slight facial dysmorphism, DNA microarray on peripheral blood should be considered early in the diagnostic work-up.

An additional patient with 3q27.3 microdeletion syndrome

The 3q27.3 microdeletion syndrome has been recently delineated in 7 subjects from 5 families sharing a 1.4 Mb smallest region of overlap. This condition appears recognizable by the association of Marfanoid habitus, mild but distinctive facial dysmorphism, intellectual disability, psychosis, and mood disorder. Here, we describe an additional 17-year-old man with an ~7.7-Mb deletion encompassing the 3q27.3 microdeletion critical region, previously run undetected at standard karyotyping. The constellation of major clinical findings overlaps with those reported in the 7 previously published patients and thus confirms the existence of a strongly recognizable syndrome linked to imbalance of 3q27.3. The role of AHSG and, possibly, of other genes in determining the 3q27.3 microdeletion habitus is discussed by comparison of the deleted segments. The involvement of adjacent loci and genes, such as OPA1 and GP5, may contribute in this patient to novel satellite features, such as optic atrophy and subclinical coagulopathy.