Molecular cytogenetic analysis of five 2q37 deletions: refining the brachydactyly candidate region

Severe brachydactyly and short stature resulting from a novel pathogenic TRPS1 variant within the GATA DNA-binding domain

Brachydactyly type E, which can be an isolated finding or part of a syndrome in combination with other clinical anomalies, involves metacarpals and metatarsals with or without short phalanges. Herein we report two unrelated Turkish females who presented with brachydactyly type E and vitamin D deficiency in the absence of marked alterations in serum calcium, phosphate, and parathyroid hormone. After excluding disease-causing variants in two candidate genes, PTHLH and PDE4D, we identified different pathogenic variants in TRPS1, the gene mutated in patients with tricho-rhino-phalangeal syndrome (TRPS). In one of the patients, who displayed severe brachydactyly and short stature, we identified a novel heterozygous missense pathogenic variant in exon 6 (c.2783A>G, p.Tyr928Cys), located within the GATA DNA-binding domain. The second patient, who had relatively milder brachydactyly and was of normal height, carried a heterozygous nonsense pathogenic variant in exon 4 (c. 1870C>T, p.Arg624Ter), which has been previously described. Both pathogenic variants segregated in affected family members. The patients additionally showed sparse hair and a bulbous nose, consistent with the clinical features of TRPS. Our findings, in addition to identifying the genetic cause of brachydactyly in two unrelated kindreds, emphasize the role of pathogenic TRPS1 variants in the development of brachydactyly type E and highlight the GATA DNA-binding region of TRPS1 protein with respect to phenotype-genotype correlation.

Genotype and phenotype correlation in 103 individuals with 2q37 deletion syndrome reveals incomplete penetrance and supports HDAC4 as the primary genetic contributor

The 2q37 deletion syndrome, also described in the literature as brachydactyly-mental retardation syndrome (MIM 600430), is caused by deletion or haploinsufficiency of the HDAC4 gene, which encodes the histone deacetylase 4 protein. Although the most commonly described hallmark features of the 2q37 deletion syndrome include brachydactyly type E, developmental delay, obesity, autistic features, and craniofacial or skeletal dysmorphism, a literature review of 101 published cases plus two newly reported individuals indicates that there is a high degree of variability in the presence of some of the features that are considered the most characteristic of the syndrome: overweight and obesity (34%), cognitive-behavioral issues (79%), dysmorphic craniofacial features (86%), and type E brachydactyly (48%). These features overlap with other neurodevelopmental conditions, including Smith-Magenis syndrome (SMS), and may be incompletely penetrant or demonstrate variable expressivity, depending on the specific chromosomal anomaly. With the advent of fluorescence in situ hybridization (FISH), array-based comparative genomic hybridization, and next-generation DNA sequencing, more detailed molecular diagnoses are possible than in years past, enabling refined characterization of the genotype-phenotype correlation for subjects with 2q37 deletions. In addition, investigations into molecular and gene expression networks are expanding in neurodevelopmental conditions, and we surveyed HDAC4 downstream gene expression by quantitative real-time polymerase chain reaction, further implicating HDAC4 in its role in the regulation of RAI1. Correlation of clinical data defining the impact on downstream gene expression and the potential clinical associations across neurodevelopment will improve our understanding of these complex conditions and potentially lead to common therapeutic approaches.

Reorganization of inter-chromosomal interactions in the 2q37-deletion syndrome

Chromosomes occupy distinct interphase territories in the three-dimensional nucleus. However, how these chromosome territories are arranged relative to one another is poorly understood. Here, we investigated the inter-chromosomal interactions between chromosomes 2q, 12, and 17 in human mesenchymal stem cells (MSCs) and MSC-derived cell types by DNA-FISH We compared our findings in normal karyotypes with a three-generation family harboring a 2q37-deletion syndrome, featuring a heterozygous partial deletion of histone deacetylase 4 (HDAC4) on chr2q37. In normal karyotypes, we detected stable, recurring arrangements and interactions between the three chromosomal territories with a tissue-specific interaction bias at certain loci. These inter-chromosomal interactions were confirmed by Hi-C. Interestingly, the disease-related HDAC4 deletion resulted in displaced inter-chromosomal arrangements and altered interactions between the deletion-affected chromosome 2 and chromosome 12 and/or 17 in 2q37-deletion syndrome patients. Our findings provide evidence for a direct link between a structural chromosomal aberration and altered interphase architecture that results in a nuclear configuration, supporting a possible molecular pathogenesis.

Heterogeneity of a Constitutional Complex Chromosomal Rearrangement in 2q

Complex chromosome rearrangements (CCRs) are unusual structural chromosome alterations found in humans, and to date only a few have been characterized molecularly. New mechanisms, such as chromothripsis, have been proposed to explain the presence of the CCRs in cancer cells and in patients with congenital disorders and/or mental retardation. The aim of the present study was the molecular characterization of a constitutional CCR in a girl with multiple congenital disorders and intellectual disability in order to determine the genotype-phenotype relation and to clarify whether the CCR could have been caused by chromosomal catastrophic events. The present CCR was characterized by G-banding, high-resolution CGH, multiplex ligation-dependent probe amplification and subtelomeric 2q-FISH analyses. Preliminary results indicate that the de novo CCR is unbalanced showing a 2q37.3 deletion and 2q34q37.2 partial trisomy. Our patient shows some of the typical traits and intellectual disability described in patients with 2q37 deletion and also in carriers of 2q34q37.2 partial trisomy; thus, the clinical disorders could be explained by additional effects of both chromosome alterations (deletions and duplications). A posterior, sequential FISH study using BAC probes revealed the unexpected presence of at least 17 different reorganizations affecting 2q34q37.2, suggesting the existence of chromosome instability in this region. The present CCR is the first case described in the literature of heterogeneity of unbalanced CCRs affecting a small region of 2q, indicating that the mechanisms involved in constitutional chromosome rearrangement may be more complex than previously thought.

A novel 2q37 microdeletion containing human neural progenitors genes including STK25 results in severe developmental delay, epilepsy, and microcephaly

2q37 microdeletion syndrome is a rare syndrome characterized by neurodevelopmental delay, bone, cardiovascular, and neurological alterations. This syndrome is typically associated with loss of genetic material of approximately 100 genes in the 2q37 band. However, the genes associated with neurodevelopmental phenotype in this syndrome are still unknown. We identified a deleted region of 496 kb by whole genome array CGH in a patient who fulfilled criteria for 2q37 microdeletion syndrome with developmental delay, microcephaly, hypoplasia of the corpus callosum, hand wringing, toe walking, and seizures. The deleted segment contains genes that are highly expressed in the developing human cortical plate and the subventricular zone (SVZ) in vivo and human neural progenitors in vitro, including SEPT2, THAP4, ATG4B, PPP1R7, and STK25. Network analysis revealed that STK25 was the most interacting gene associated with neural development in this deletion. Our report narrows the likely causative genomic region for microcephaly and neurodevelopmental delay in 2q37 microdeletion syndrome to a small genomic region enriched with neural progenitor genes that may represent an important locus for the development of the human cortex and corpus callosum.

35-Year Follow-Up of a Case of Ring Chromosome 2: Array-CGH Analysis and Literature Review of the Ring Syndrome

Côté et al. [1981] suggested that ring chromosomes with or without deletions share a common pattern of phenotypic anomalies, regardless of which chromosome is involved. The phenotype of this 'general ring syndrome' consists of growth failure without malformations, few or no minor anomalies, and mild to moderate mental retardation. We reconsidered the ring chromosome 2 case previously published by Côté et al. [1981], and we characterized it by array CGH, polymorphic markers as well as subtelomere MLPA and FISH analysis. A terminal deletion (q37.3qter) of maternal origin of the long arm of the ring chromosome 2 was detected and confirmed by all the above-mentioned methods. Ring chromosome 2 cases are exceedingly rare. Only 18 cases, including the present one, have been published so far, and our patient is the longest reported survivor, with a 35-year follow-up, and the third case characterized by array-CGH analysis.

Neuropsychological profiles of patients with 2q37.3 deletion associated with developmental dyspraxia

Patients with 2q37 deletions manifest brachydactyly mental retardation syndrome (BDMR). Recent advances in human molecular research have revealed that alterations in the histone deacetylase 4 gene (HDAC4) are responsible for the clinical manifestations of BDMR. Here, we report two male patients with 2q37.3 deletions. One of the patients showed a typical BDMR phenotype, and HDAC4 was included in the deletion region. HDAC4 was preserved in the other patient, and he showed a normal intelligence level with the delayed learning of complex motor skills. Detailed neuropsychological examinations revealed similar neuropsychological profiles in these two patients (visuo-spatial dyspraxia) that suggested developmental dyspraxia. These observations suggested that some other candidate genes for neuronal development exist in the telomeric region of HDAC4.

The first familial case of inherited 2q37.3 interstitial deletion with isolated skeletal abnormalities including brachydactyly type E and short stature

Albright hereditary osteodystrophy (AHO)-like syndrome is also known as brachydactyly-mental retardation syndrome (BDMR; OMIM 60040). This disorder includes intellectual disability in all patients, skeletal abnormalities, including brachydactyly E (BDE) in approximately half, obesity, and facial dysmorphism. Patients with 2q37 microdeletion or HDAC4 mutation are defined as having an AHO-like phenotype with normal stimulatory G (Gs) function. HDAC4 is involved in neurological, cardiac, and skeletal function. This paper reports the first familial case of 2q37.3 interstitial deletion affecting two genes, HDAC4 and TWIST2. Patients presented with BDE and short stature without intellectual disability, showing that haploinsufficiency of the HDAC4 critical region may lead to a spectrum of phenotypes, ranging from isolated brachydactyly type E to BDMR.

SOcK, MiSTs, MASK and STicKs: the GCKIII (germinal centre kinase III) kinases and their heterologous protein-protein interactions

The GCKIII (germinal centre kinase III) subfamily of the mammalian Ste20 (sterile 20)-like group of serine/threonine protein kinases comprises SOK1 (Ste20-like/oxidant-stress-response kinase 1), MST3 (mammalian Ste20-like kinase 3) and MST4. Initially, GCKIIIs were considered in the contexts of the regulation of mitogen-activated protein kinase cascades and apoptosis. More recently, their participation in multiprotein heterocomplexes has become apparent. In the present review, we discuss the structure and phosphorylation of GCKIIIs and then focus on their interactions with other proteins. GCKIIIs possess a highly-conserved, structured catalytic domain at the N-terminus and a less-well conserved C-terminal regulatory domain. GCKIIIs are activated by tonic autophosphorylation of a T-loop threonine residue and their phosphorylation is regulated primarily through protein serine/threonine phosphatases [especially PP2A (protein phosphatase 2A)]. The GCKIII regulatory domains are highly disorganized, but can interact with more structured proteins, particularly the CCM3 (cerebral cavernous malformation 3)/PDCD10 (programmed cell death 10) protein. We explore the role(s) of GCKIIIs (and CCM3/PDCD10) in STRIPAK (striatin-interacting phosphatase and kinase) complexes and their association with the cis-Golgi protein GOLGA2 (golgin A2; GM130). Recently, an interaction of GCKIIIs with MO25 has been identified. This exhibits similarities to the STRADα (STE20-related kinase adaptor α)-MO25 interaction (as in the LKB1-STRADα-MO25 heterotrimer) and, at least for MST3, the interaction may be enhanced by cis-autophosphorylation of its regulatory domain. In these various heterocomplexes, GCKIIIs associate with the Golgi apparatus, the centrosome and the nucleus, as well as with focal adhesions and cell junctions, and are probably involved in cell migration, polarity and proliferation. Finally, we consider the association of GCKIIIs with a number of human diseases, particularly cerebral cavernous malformations.

Brachydactyly E: isolated or as a feature of a syndrome

Brachydactyly (BD) refers to the shortening of the hands, feet or both. There are different types of BD; among them, type E (BDE) is a rare type that can present as an isolated feature or as part of more complex syndromes, such as: pseudohypopthyroidism (PHP), hypertension with BD or Bilginturan BD (HTNB), BD with mental retardation (BDMR) or BDE with short stature, PTHLH type. Each syndrome has characteristic patterns of skeletal involvement. However, brachydactyly is not a constant feature and shows a high degree of phenotypic variability. In addition, there are other syndromes that can be misdiagnosed as brachydactyly type E, some of which will also be discussed. The objective of this review is to describe some of the syndromes in which BDE is present, focusing on clinical, biochemical and genetic characteristics as features of differential diagnoses, with the aim of establishing an algorithm for their differential diagnosis. As in our experience many of these patients are recruited at Endocrinology and/or Pediatric Endocrinology Services due to their short stature, we have focused the algorithm in those steps that could mainly help these professionals.

Phenotypic variant of Brachydactyly-mental retardation syndrome in a family with an inherited interstitial 2q37.3 microdeletion including HDAC4

Deletions of the chromosomal region 2q37 cause brachydactyly-mental retardation syndrome (BDMR), also known as Albright hereditary osteodystrophy-like syndrome. Recently, histone deacetylase 4 (HDAC4) haploinsufficiency has been postulated to be the critical genetic mechanism responsible for the main clinical characteristics of the BDMR syndrome like developmental delay and behavioural abnormalities in combination with brachydactyly type E (BDE). We report here on the first three generation familial case of BDMR syndrome with inheritance of an interstitial microdeletion of chromosome 2q37.3. The deletion was detected by array comparative genomic hybridization and comprises the HDAC4 gene and two other genes. The patients of this pedigree show a variable severity of psychomotor and behavioural abnormalities in combination with a specific facial dysmorphism but without BDE. Given that only about half of the patients with 2q37 deletions have BDE; we compared our patients with other patients carrying 2q37.3 deletions or HDAC4 mutations known from the literature to discuss the diagnostic relevance of the facial dysmorphism pattern in 2q37.3 deletion cases involving the HDAC4 gene. We conclude that HDAC4 haploinsufficiency is responsible for psychomotor and behavioural abnormalities in combination with the BDMR syndrome-specific facial dysmorphism pattern and that these clinical features have a central diagnostic relevance.

The 2q37-deletion syndrome: an update of the clinical spectrum including overweight, brachydactyly and behavioural features in 14 new patients

The 2q37 locus is one of the most commonly deleted subtelomeric regions. Such a deletion has been identified in >100 patients by telomeric fluorescence in situ hybridization (FISH) analysis and, less frequently, by array-based comparative genomic hybridization (array-CGH). A recognizable '2q37-deletion syndrome' or Albright's hereditary osteodystrophy-like syndrome has been previously described. To better map the deletion and further refine this deletional syndrome, we formed a collaboration with the Association of French Language Cytogeneticists to collect 14 new intellectually deficient patients with a distal or interstitial 2q37 deletion characterized by FISH and array-CGH. Patients exhibited facial dysmorphism (13/14) and brachydactyly (10/14), associated with behavioural problems, autism or autism spectrum disorders of varying severity and overweight or obesity. The deletions in these 14 new patients measured from 2.6 to 8.8 Mb. Although the major role of HDAC4 has been demonstrated, the phenotypic involvement of several other genes in the deleted regions is unknown. We further refined the genotype-phenotype correlation for the 2q37 deletion. To do this, we examined the smallest overlapping deleted region for candidate genes for skeletal malformations (facial dysmorphism and brachydactyly), overweight, behavioural problems and seizures, using clinical data, a review of the literature, and the Manteia database. Among the candidate genes identified, we focus on the roles of PRLH, PER2, TWIST2, CAPN10, KIF1A, FARP2, D2HGDH and PDCD1.

Primary hyperoxaluria type 1 and brachydactyly mental retardation syndrome caused by a novel mutation in AGXT and a terminal deletion of chromosome 2

Primary hyperoxaluria type 1 (PH1) is an autosomal recessive disorder caused by mutations in the alanine:glyoxylate aminotransferase (AGXT) gene, located on chromosome 2q37. Mutant AGXT leads to excess production and excretion of oxalate, resulting in accumulation of calcium oxalate in the kidney, and progressive loss of renal function. Brachydactyly mental retardation syndrome (BDMR) is an autosomal dominant disorder, caused by haploinsufficiency of histone deacetylase 4 (HDAC4), also on chromosome 2q37. It is characterized by skeletal abnormalities and developmental delay. Here, we report on a girl who had phenotypes of both PH1 and BDMR. PCR-sequencing of the coding regions of AGXT showed a novel missense mutation, c.32C>G (p.Pro11Arg) inherited from her mother. Functional analyses demonstrated that it reduced the enzymatic activity to 31% of the wild-type and redirected some percentage of the enzyme away from the peroxisome. Microsatellite and array-CGH analyses indicated that the proband had a paternal de novo telomeric deletion of chromosome 2q, which included HDAC4. To our knowledge, this is the first report of PH1 and BDMR, with a novel AGXT mutation and a de novo telomeric deletion of chromosome 2q.

Dose dependent expression of HDAC4 causes variable expressivity in a novel inherited case of brachydactyly mental retardation syndrome

Histone deacetylase 4 (HDAC4) serves important roles in multiple human systems, including neurological, cardiac, and skeletal functions. Mutation or deletion of HDAC4 causes brachydactyly mental retardation syndrome (BDMR), a disorder that includes intellectual disability, behavioral abnormalities, autism spectrum disorder, and craniofacial and skeletal anomalies, including brachydactyly type E. We present a case of familial BDMR, including a parent with mild symptoms of the disorder and a child exhibiting a more severe phenotype. Cytogenetic testing showed a cryptic balanced translocation in the mother that resulted in a 2q37.1 monosomy and a 10q26.1 trisomy in the son. Gene expression analyses demonstrated 67% HDAC4 expression in the mother and 23% HDAC4 expression in the son relative to normal controls, lending evidence to the hypothesis that HDAC4 modulates severity of this disorder in a dosage-dependent manner.

A novel deletion in 2q24.1q24.2 in a girl with mental retardation and generalized hypotonia: a case report

Background

Chromosomal imbalances, recognized as the major cause of mental retardation, are often due to submicroscopic deletions or duplications not evidenced by conventional cytogenetic methods. To date, interstitial deletion of long arm of chromosome 2 have been reported for more than 100 cases, although studies reporting small interstitial deletions involving the 2q24.1q24.2 region are rare. With the widespread clinical use of comparative genomic hybridization chromosomal microarray technology, several cryptic chromosome imbalances have outlined new genotype-phenotype correlations and isolated a number of distinctive clinical conditions.

Results

here we report on a girl with mental retardation and generalized hypotonia. A genome-wide screen for copy number variations (CNVs) using single nucleotide polymorphisms (SNPs) array revealed a 7.5 Mb interstitial deletion of chromosome region 2q24.1q24.2 encompassing 59 genes, which was absent in parents. The gene content analysis of the deleted region and review of the literature revealed the presence of some genes that may be indicated as good candidate in generating the main clinical features of the patient.

Discussion

the present case represents a further patient described in the literature with an interstitial deletion of chromosome 2q24.1q24.2. Our patient shares some clinical features with the previously reported patients carriers of overlapping 2q24 deletion. Although more cases are needed to delineate the full-blown phenotype of 2q24.1q24.2 deletion syndrome, published data and present observation suggest that hemizygosity of this region results in a clinically recognizable phenotype. Considering these clinical and cytogenetic similarities, we suggest the existence of an emerging syndrome associated to 2q24.1q24.2 region.

Molecular characterization of a new patient with a non-recurrent inv dup del 2q and review of the mechanisms for this rearrangement

We report on newborn baby with microcephaly, facial anomalies, congenital heart defects, hypotonia, wrist contractures, long fingers, adducted thumbs, and club feet. Cytogenetic studies revealed an inverted duplication with terminal deletion (inv dup del) of 2q in the patient and a paternal 2qter deletion polymorphism. Microsatellite markers demonstrated that the inv dup del was maternal in origin and intrachromosomal. Intra or interchromosomal rearrangements may cause this aberration either by a U-type exchange (end-to-end fusion), an unequal crossover between inverted repeats (non-allelic homologous recombination: NAHR), or through breakage-fusion-bridge (BFB) cycles leading to a sister chromatid fusion by non-homologous end joining (NHEJ). A high-resolution oligo array-CGH (244 K) defined the breakpoints and did not detect a single copy region with a size exceeding 12.93 Kb in the fusion site. The size of the duplicated segment was 38.75 Mb, extending from 2q33.1 to 2q37.3 and the size of the terminal deletion was 2.85 Mb in 2q37.3. Our results indicate that the inv dup del (2q) is likely a non-recurrent chromosomal rearrangement generated by a NHEJ mechanism. The major clinical characteristics associated with this 2q rearrangement overlap with those commonly found in patients with 2q duplication reported in the literature.

Ectodermal dysplasia-like syndrome with mental retardation due to contiguous gene deletion: further clinical and molecular delineation of del(2q32) syndrome

We report on a patient with an interstitial deletion of the long arm of chromosome 2 at 2q31.2q33.2. She had prenatal and postnatal growth retardation, microcephaly, facial dysmorphism, cleft palate, camptodactyly, bilateral talipes equinovarus, severe intellectual disability, and ectodermal anomalies. She showed thin, atrophic skin, sparse, brittle, slowly growing hair, oligodontia with abnormally shaped teeth, normal sweating, and normal fingernails, consistent with a diagnosis of ectodermal dysplasia. Array CGH analysis (Agilent 44K) showed the deletion to span 26 Mb, between cytogenetic bands 2q31.2 and 2q33. The deletion leads to hemizygosity for the HOXD cluster and its regulatory elements, COL3A1/COL5A2, GTF3C3, CASP8, CASP10, and SABT2 could perhaps interfere with long range control of DLX1 and DLX2 expression. This girl confirms the existence of a clinically recognizable 2q32 microdeletion syndrome, as recently delineated by Van Buggenhout et al. and confirms a novel putative locus for ectodermal dysplasia on chromosome 2q31q33. We recommend considering cytogenetic and/or molecular screening for del(2q32) in patients with developmental disability and ectodermal dysplasia-like phenotype, including thin skin, oligodontia, dysplastic teeth, and sparse hair.

Loss of heterozygosity at 2q37 in sporadic Wilms' tumor: putative role for miR-562

PURPOSE

Wilms' tumor is a childhood cancer of the kidney with an incidence of approximately 1 in 10,000. Cooccurrence of Wilms' tumor with 2q37 deletion syndrome, an uncommon constitutional chromosome abnormality, has been reported previously in three children. Given these are independently rare clinical entities, we hypothesized that 2q37 harbors a tumor suppressor gene important in Wilms' tumor pathogenesis.

EXPERIMENTAL DESIGN

To test this, we performed loss of heterozygosity analysis in a panel of 226 sporadic Wilms' tumor samples and mutation analysis of candidate genes.

RESULTS

Loss of heterozygosity was present in at least 4% of cases. Two tumors harbored homozygous deletions at 2q37.1, supporting the presence of a tumor suppressor gene that follows a classic two-hit model. However, no other evidence of second mutations was found, suggesting that heterozygous deletion alone may be sufficient to promote tumorigenesis in concert with other genomic abnormalities. We show that miR-562, a microRNA within the candidate region, is expressed only in kidney and colon and regulates EYA1, a critical gene for renal development. miR-562 expression is reduced in Wilms' tumor and may contribute to tumorigenesis by deregulating EYA1. Two other candidate regions were localized at 2q37.3 and 2qter, but available data from patients with constitutional deletions suggest that these probably do not confer a high risk for Wilms' tumor.

CONCLUSIONS

Our data support the presence of a tumor suppressor gene at 2q37.1 and suggest that, in individuals with constitutional 2q37 deletions, any increased risk for developing Wilms' tumor likely correlates with deletions encompassing 2q37.1.

Deletion 2q37: an identifiable clinical syndrome with mental retardation and autism

Terminal deletion of the long arm of chromosome 2 is a rare chromosomal disorder characterized by low birth weight, delayed somatic and mental development, craniofacial defects, short neck, heart and lung congenital defects, and autistic features. We report on a girl with 46,XX.ish del(2)(q37.1) de novo karyotype, mental retardation, dysmorphic features, gastrointestinal anomalies, and autistic traits and compare her clinical manifestations with patients with the same deletion previously described in literature.

Chromosome 2q37 deletion: clinical and molecular aspects

Terminal deletions of chromosome 2 with breakpoints at or within band 2q37, ranging from visible abnormalities to cryptic, subtelomeric deletions, have been recognized with increasing frequency among children with mild-moderate mental retardation, characteristic facial appearance, and behavioral manifestations which often place them on the autism spectrum. The stereotypic facial characteristics include prominent forehead, thin, highly arched eyebrows, depressed nasal bridge, full cheeks, deficient nasal alae and prominent columella, thin upper lip, and various minor anomalies of the pinnae. Abnormal nipples, including inverted nipples, have been reported in a number of cases. CNS, ocular, cardiac, gastrointestinal, renal, and other GU anomalies have been noted in nearly one-third of patients. Of note, coarctation or hypoplasia of the aorta has been described in several affected children. Wilms tumor, renal dysplasia, and tracheomalacia have been reported only with the most proximal breakpoint at band 2q37.1 while a range of GI anomalies, pyloric stenosis, and diaphragmatic defects have been reported with breakpoints throughout the region. A subset of patients with the most distal deletion present phenotypic features which mimic Albright hereditary osteodystrophy (AHO). In addition to the AHO-like phenotype, later onset findings include seizures and cystic kidneys. Timely diagnosis of this recognizable syndrome provides a basis for genetic counseling, appropriate surveillance, and intervention, and avoids unnecessary and expensive diagnostic testing.

2q24–q31 Deletion: Report of a case and review of the literature

We report a patient with a de novo interstitial deletion of the long arm of chromosome 2 involving bands 2q24.3-q31.1. The patient shows postnatal growth retardation, microcephaly, ptosis, down-slanting palpebral fissures, long eyelashes and micrognathia. Halluces are long, broad and medially deviated, while the other toes are laterally deviated and remarkably short with hypoplastic phalanges. She also showed developmental delay, seizures, lack of eye contact, stereotypic and repetitive hand movements and sleep disturbances with breath holding. Prenatal and three independent postnatal karyotypes were normal. Array-CGH analysis allowed us to identify and characterize a "de novo" 2q interstitial deletion of about 10.4Mb, involving segment between cytogenetic bands 2q24.3 and 2q31.1. The deletion was confirmed by quantitative PCR. About 30 children with 2q interstitial deletion have been reported. The deletion described here is overlapping with 15 of these cases. We have attempted to compare the clinical features of our patient with 15 overlapping cases. The emerging phenotypes include low birth weight, postnatal growth retardation, mental retardation and developmental delay, microcephaly, and peculiar facial dysmorphisms. Peculiar long and broad halluces with an increased distance between the first and the second toe are ("sandal gap" sign) present in most of the described patients. The gene content analysis of the deleted region revealed the presence of some genes that may be indicated as good candidates in generating both neurological and dysmorphic phenotype in the patient. In particular, a cluster of SCNA genes is located within the deleted region and it is known that loss of function mutations in SCNA1 gene cause a severe form of epilepsy.

Array-CGH analysis and clinical description of 2q37.3 de novo subtelomeric deletion

We report on a 13-year-old girl with normal karyotype and a de novo cryptic terminal deletion of chromosome 2q, detected by subtelomeric FISH analysis. Further investigation with array-CGH analysis using the 1Mb resolution Spectral Chip 2600 (Spectral Genomics) confirmed the deletion and also showed a deletion of four additional clones. No other abnormalities were detected by array-CGH. FISH studies using 8 BAC-probes were performed for fine mapping of the deletion and confirmed the array results. FISH analysis showed that the deletion breakpoint lies between clones RP11-84G18 and RP11-83N2 (physical distance between clones 0.36Mb) and extends to the telomere. The size of the deletion was estimated to be about 6.4-6.7Mb. Clinical findings include: developmental delay, severe behavioural disturbances, growth-pubertal retardation, congenital conductive mild hearing loss, growth hormone deficiency, compensate hypothyroidism, dysmorphic facial features, excessive joint hypermobility, brachymetaphalangy, abnormal dermatoglyphics and a history of neonatal laryngomalacia, hypotonia and umbilical hernia. The phenotype of our patient is in keeping with those of the literature, with the exception of cardiovascular, urogenital, neurological anomalies and eczema, which were not observed. The report of the clinical and molecular presentation of similar cases will allow accurate phenotype-genotype correlation and proper genetic counseling of the family.