Further delineation of the partial proximal trisomy 10q syndrome

Clinical Characterization of a 6-Year-Old Patient with Autism and Two Adjacent Duplications on 10q11.22q11.23. A Case Report

Autism is a neurodevelopmental disorder presenting in the first 3 years of life. Deficits occur in the core areas of social communication and interaction and restricted, repetitive patterns of behavior, interests or activities. The causes of autism are unknown, but clinical genetic studies show strong evidence in favor of the involvement of genetic factors in etiology. Molecular genetic studies report some associations with candidate genes, and candidate regions have emerged from several genome-wide linkage studies. Here, we report a clinical case of autism in a 6-year-old boy with double duplication on 10q11.22q11.23 with ASD (Autism Spectrum Disorder), intellectual disability, developmental delay, hypotonia, gross-motor skills deficit, overgrowth and mild dysmorphic features. In the literature, only five cases of ASD with 10q11.21q11.23 duplication are reported. This is the first extensive clinical description of an ASD subject with 10q11.22q11.23 duplication. Our findings suggest that 10q11.21q11.23 microduplication could represent a copy number variant that predisposes to autism.

Megalencephaly and hemimegalencephaly: breakthroughs in molecular etiology

Megalencephaly (MEG) is a developmental disorder characterized by brain overgrowth that occurs due to either increased number or size of neurons and glial cells. The former may be due to either increased neuronal proliferation or decreased apoptosis. The degree of brain overgrowth may be extensive, ranging from generalized MEG affecting the entire cortex-as with mutations in PTEN (phosphatase and tensin homolog on chromosome ten)-to unilateral hemispheric malformations-as in classic hemimegalencephaly (HME). On the other hand, some lesions are more focal or segmental. These developmental brain abnormalities may occur in isolation in some individuals, whereas others occur in the context of a syndrome involving dysmorphic features, skin findings, or other organ system involvement. Brain overgrowth disorders are often associated with malformations of cortical development, resulting in increased risk of epilepsy, intellectual disability, and autistic features, and some are associated with hydrocephalus. The past few years have witnessed a dramatic leap in our understanding of the molecular basis of brain overgrowth, particularly the identification of mosaic (or post-zygotic) mutations in core components of key cellular pathways such as the phosphatidylinositol 3-kinase (PI3K)-vakt murine thymoma viral oncogene homolog (AKT)-mTOR pathway. These molecular insights have broadened our view of brain overgrowth disorders that now appear to span a wide spectrum of overlapping phenotypic, neuroimaging, and neuropathologic features and molecular pathogenesis. These molecular advances also bring to light the possibility of pathway-based therapies for these often medically devastating developmental disorders.

Proximal 10q duplication in a child with severe central hypotonia characterized by array-comparative genomic hybridization: A case report and review of the literature

Proximal 10q duplication is a well-defined but rare genetic syndrome. Duplication of proximal segments of the long arm of chromosome 10 results in a pattern of malformations, which are distinct from those of the more common distal 10q trisomy syndrome. The present study describes the case of a boy with phenotypic abnormalities (severe central hypotonia, mild ataxia, moderate developmental delay and mild dysmorphic features), due to duplication of chromosome region, 10q11.21→q11.22, which was characterized by the array-comparative genomic hybridization (CGH) technique. The phenotypic findings were compared with those in eight additional similar published cases. Major similarities have emerged, suggesting a likely minimal critical region. However, only detailed characterization of additional cases may provide firm conclusions.

The use of array-CGH in a cohort of Greek children with developmental delay

Background

The genetic diagnosis of mental retardation (MR) is difficult to establish and at present many cases remain undiagnosed and unexplained. Standard karyotyping has been used as one of the routine techniques for the last decades. The implementation of Array Comparative Genomic Hybridization (array-CGH) has enabled the analysis of copy number variants (CNVs) with high resolution. Major cohort studies attribute 11% of patients with unexplained mental retardation to clinically significant CNVs. Here we report the use of array-CGH for the first time in a Greek cohort. A total of 82 children of Greek origin with mean age 4.9 years were analysed in the present study. Patients with visible cytogenetic abnormalities ascertained by standard karyotyping as well as those with subtelomeric abnormalities determined by Multiplex Ligation-dependent Probe Amplification (MLPA) or subtelomeric FISH had been excluded.

Results

Fourteen CNVs were detected in the studied patients. In nine patients (11%) the chromosomal aberrations were inherited from one of the parents. One patients showed two duplications, a 550 kb duplication in 3p14.1 inherited from the father and a ~1.1 Mb duplication in (22)(q13.1q13.2) inherited from the mother. Although both parents were phenotypically normal, it cannot be excluded that the dual duplication is causative for the patient's clinical profile including dysmorphic features and severe developmental delay. Furthermore, three de novo clinically significant CNVs were detected (3.7%). There was a ~6 Mb triplication of 18q21.1 in a girl 5 years of age with moderate MR and mild dysmorphic features and a ~4.8 Mb duplication at (10)(q11.1q11.21) in a 2 years old boy with severe MR, multiple congenital anomalies, severe central hypotonia, and ataxia. Finally, in a 3 year-old girl with microcephaly and severe hypotonia a deletion in (2)(q31.2q31.3) of about ~3.9 Mb was discovered. All CNVs were confirmed by Fluorescence in situ hybridization (FISH). For the remaining 9 patients the detected CNVs (inherited duplications or deletions of 80 kb to 800 kb in size) were probably not associated with the clinical findings.

Conclusions

Genomic microarrays have within the recent years proven to be a highly useful tool in the investigation of unexplained MR. The cohorts reported so far agree on an around 11% diagnostic yield of clinically significant CNVs in patients with unexplained MR. Various publicly available databases have been created for the interpretation of identified CNVs and parents are analyzed in case a rare CNV is identified in the child. We have conducted a study of Greek patients with unexplained MR and confirmed the high diagnostic value of the previous studies. It is important that the technique becomes available also in less developed countries when the cost of consumables will be reduced.

Partial proximal 10q trisomy: a new case associated with biliary atresia

Herein we describe a unique case of partial proximal 10q trisomy presenting biliary atresia, anal anteposition and cardiac malformation. The 10q duplication was confirmed by G banding on prophase chromosomes. A review of the literature confirmed that the patient displayed characteristic dysmorphic features of the recently defined partial proximal trisomy 10q syndrome and emphasized the interindividual variability of visceral malformations.

De novostructural chromosomal imbalances: molecular cytogenetic characterization of partial trisomies

De novo structural chromosomal imbalances represent a major challenge in modern cytogenetic diagnostics. Based solely on conventional cytogenetic techniques it may be impossible to identify the chromosomal origin of additional chromosomal material. In these cases molecular cytogenetic investigations including multicolor-FISH (M-FISH), spectral karyotyping (SKY), multicolor banding (MCB) and cenM-FISH combined with appropriate single-locus FISH probes are highly suitable for the determination of the chromosomal origin and fine characterization of derivative chromosomes. Here we report on four patients with de novo chromosomal imbalances and distinct chromosomal phenotypes, three of them harboring pure partial trisomies: a mildly affected boy with pure partial trisomy 10q22.2-->q22.3 approximately 23.1 due to an interstitial duplication, a girl with pure trisomy 12p11.21-->pter and atypically moderate phenotype as the consequence of an X;autosome translocation, and a girl with multiple congenital abnormalities and severe developmental delay and a 46,XX,15p+ karyotype hiding a trisomy 17pter-->17q11.1. The fourth patient is a girl with minor phenotypic features and mental retardation with an inverted duplication 18q10-->p11.31 combined with a terminal deletion of 18p32. The clinical pictures are compared with previously described patients with focus on long term outcome.

First small supernumerary ring chromosome carrying 10q euchromatin in a patient with mild phenotype characterized by molecular cytogenetic techniques and review of the literature

We report the identification and characterization of the first supernumerary ring chromosome 10 containing a considerable proportion of 10q euchromatin by microdissection and reverse painting in a female patient presenting with short stature. Fluorescence in situ hybridization studies showed that the marker chromosome originates from chromosome 10 and includes the euchromatic bands p11.2 and q11.2. The supernumerary marker chromosome 10 was found in 14% of the peripheral blood lymphocytes analyzed. This constitutional mosaic could be confirmed in oral mucosa cells as a second cell system (16%) by interphase FISH using an alphoid centromeric probe for chromosome 10. Parental karyotypes were normal, uniparental disomy for the normal chromosomes 10 could be excluded by microsatellite analysis. The karyotype of the patient detected in peripheral blood cells can be described as mos 47,XX,+mar.rev ish r(10)(p11.2q11.2)(wcp10+,cep10+)/46,XX.

Partial trisomy of chromosome 10(q22-q24) due to maternal insertional translocation (15;10)

Interchromosomal insertional translocations are rare chromosome rearrangements with an incidence of about 1:80,000 live births. We report on the clinical and cytogenetic findings of a newborn baby with partial trisomy 10q22-10q24 due to a maternal insertional translocation 15;10. Partial trisomy of the long arm of chromosome 10 is a distinctive chromosome aberration characterized by prenatal-onset growth retardation and craniofacial, skeletal, and other somatic anomalies. Most cases are unbalanced products from reciprocal chromosome translocations, and insertional translocations are rarely involved. The proband was initially referred because of severe intrauterine growth retardation, and fluorescence in situ hybridization (FISH) using painting probes confirmed the maternal balanced (15;10) insertion.