Chromosomal microarray analysis in the genetic evaluation of 279 patients with syndromic obesity.

Background: Syndromic obesity is an umbrella term used to describe cases where obesity occurs with additional phenotypes. It often arises as part of a distinct genetic syndrome with Prader-Willi syndrome being a classical example. These rare forms of obesity provide a unique source for identifying obesity-related genetic changes.

Dual molecular diagnosis contributes to atypical Prader-Willi phenotype in monozygotic twins.

We describe monozygotic twin girls with genetic variation at two separate loci resulting in a blended phenotype of Prader-Willi syndrome and Pitt-Hopkins syndrome. These girls were diagnosed in early infancy with Prader-Willi syndrome, but developed an atypical phenotype, with apparent intellectual deficiency and lack of obesity. Array-comparative genomic hybridization confirmed a de novo paternal deletion of the 15q11.

Obesity with associated developmental delay and/or learning disability in patients exhibiting additional features: report of novel pathogenic copy number variants.

Obesity is a major threat to public health worldwide, and there is now mounting evidence favoring a role for the central nervous system (CNS) in weight control. A causal relationship has been recognized in both monogenic (e.g.

Angelman syndrome caused by deletion: a genotype-phenotype correlation determined by breakpoint.

Objectives: Deletion of the chromosome 15q11-q13, the most common genetic mechanism associated with Angelman syndrome (AS), is highly associated with a severe phenotype. However, deletion is not a genetically homogeneous group as it is composed by two main groups: Class I with breakpoints at BP1 (proximal) and BP3 (distal) and Class II present breakpoints at BP2 (proximal) and BP3 (distal). In this study, we aimed to evaluate the impact of the breakpoint on the electroclinical profile.

A clinical follow-up of 35 Brazilian patients with Prader-Willi syndrome.

Objective: Prader-Willi Syndrome is a common etiology of syndromic obesity that is typically caused by either a paternal microdeletion of a region in chromosome 15 (microdeletions) or a maternal uniparental disomy of this chromosome. The purpose of this study was to describe the most significant clinical features of 35 Brazilian patients with molecularly confirmed Prader-Willi syndrome and to determine the effects of growth hormone treatment on clinical outcomes.

Methods: A retrospective study was performed based on the medical records of a cohort of 35 patients diagnosed with Prader-Willi syndrome.

Deletion of the RMGA and CHD2 genes in a child with epilepsy and mental deficiency.

We describe a novel chromosome microdeletion at 15q26.1 detected by oligo-array-CGH in a 6-year-old girl presenting with global development delay, epilepsy, autistic behavior and facial dysmorphisms. Although these features are often present in Angelman syndrome, no alterations were present in the methylation pattern of the Prader-Willi-Angelman critical region.

A rare case of trisomy 15pter-q21.2 due to a de novo marker chromosome.

Supernumerary marker chromosomes (sSMC) may or may not be associated with an abnormal phenotype, depending on the presence of euchromatin, on their chromosomal origin and whether they are inherited. Over 80% of sSMCs are derived from acrocentric chromosomes and half of them include the short arm of chromosome 15. Generally, they appear as bisatellited isodicentric marker chromosomes, most of them are symmetric.

Extending the phenotype of monosomy 1p36 syndrome and mapping of a critical region for obesity and hyperphagia.

Rearrangements of 1p36 are the most frequently detected abnormalities in diagnostic testing for chromosomal cryptic imbalances and include variably sized simple terminal deletions, derivative chromosomes, interstitial deletions, and complex rearrangements. These rearrangements result in the specific pattern of malformation and neurodevelopmental disabilities that characterizes monosomy 1p36 syndrome. Thus far, no individual gene within this region has been conclusively determined to be causative of any component of the phenotype.

Microdeletion encompassing MAPT at chromosome 17q21.3 is associated with developmental delay and learning disability.

Recently, the application of array-based comparative genomic hybridization (array CGH) has improved rates of detection of chromosomal imbalances in individuals with mental retardation and dysmorphic features. Here, we describe three individuals with learning disability and a heterozygous deletion at chromosome 17q21.3, detected in each case by array CGH.

A new case of interstitial 6q16.2 deletion in a patient with Prader-Willi-like phenotype and investigation of SIM1 gene deletion in 87 patients with syndromic obesity.

The association of obesity, phenotypic abnormalities and mental retardation characterizes syndromic obesity. Its most common form is the Prader-Willi syndrome (PWS-- neonatal hypotonia, poor sucking, delayed psychomotor development, hyperphagia, severe obesity, short stature, small hands and feet, hypogonadism, mild to moderate mental retardation and behavioral disorders). A PWS-like phenotype has been described in patients with chromosome abnormalities involving the chromosome region 6q16.

Prader-Willi-like phenotype: investigation of 1p36 deletion in 41 patients with delayed psychomotor development, hypotonia, obesity and/or hyperphagia, learning disabilities and behavioral problems.

Monosomy 1p36 is one of the most commonly observed mental retardation (MR) syndromes that results in a clinically recognizable phenotype including delayed psychomotor development and/or MR, hypotonia, epilepsy, hearing loss, growth delay, microcephaly, deep-set eyes, flat nasal bridge and pointed chin. Besides, a Prader-Willi syndrome (PWS)-like phenotype has been described in patients with 1p36 monosomy. Forty-one patients presenting hypotonia, developmental delay, obesity and/or hyperphagia and behavioral problems who tested negative for PWS were investigated by FISH and/or microsatellite markers.

Angelman syndrome: uniparental paternal disomy 15 determines mild epilepsy, but has no influence on EEG patterns.

The authors describe the electroclinical phenotype of four patients with Angelman syndrome (AS) determined by its rarest genetic mechanism-uniparental disomy (UPD). The analysis of ours and published patients showed that in UPD, when epilepsy occurred, it was milder compared to patients with deletion, although a suggestive EEG was observed in most patients. We found that UPD patients do not completely fit the scenario delineated for AS, suggesting that patients determined by different mechanisms should be distinctly addressed, for a better understanding of this syndrome.

Phenotypic variability in Angelman syndrome: comparison among different deletion classes and between deletion and UPD subjects.

Angelman syndrome (AS) can result from either a 15q11-q13 deletion (del), paternal uniparental disomy (UPD), imprinting, or UBE3A mutations. Here, we describe the phenotypic and behavioral variability detected in 49 patients with different classes of deletions and nine patients with UPD. Diagnosis was made by methylation pattern analysis of exon 1 of the SNRPN-SNURF gene and by microsatellite profiling of loci within and outside the 15q11-q13 region.

Prader-Willi syndrome with an unusually large 15q deletion due to an unbalanced translocation t(4;15).

Prader-Willi syndrome (PWS) is a neurobehavioral disorder caused by deletions in the 15q11-q13 region, by maternal uniparental disomy of chromosome 15 or by imprinting defects. Structural rearrangements of chromosome 15 have been described in about 5% of the patients with typical or atypical PWS phenotype. An 8-year-old boy with a clinical diagnosis of PWS, severe neurodevelopmental delay, absence of speech and mental retardation was studied by cytogenetic and molecular techniques, and an unbalanced de novo karyotype 45,XY,der(4)t(4;15)(q35;q14),-15 was detected after GTG-banding.