Two patients with duplication of 17p11.2: The reciprocal of the Smith-Magenis syndrome deletion?

J.M. and H.G. are two unrelated male patients with developmental delay. Cytogenetic analysis detected a duplication of 17p11.2 in both patients. The extent of the duplicated region was determined using single copy DNA probes: cen-D17S58-D17S29-D17S258-D17S71-D17S445-D17S122-tel. Four of the six markers, D17S29, D17S258, D17S71, and D17S445, were duplicated by dosage analysis. Fluorescent in situ hybridization (FISH) analysis of H.G., using cosmids for locus D17S29, confirmed the duplication in 17p11.2. Because the deletion that causes the Smith-Magenis syndrome involves the same region of 17p11.2 as the duplication in these patients, the mechanism may be similar to that proposed for the reciprocal deletion/duplication event observed in Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) and Charcot-Marie-Tooth Type 1A disease (CMT1A). © 1996 Wiley-Liss, Inc.     

Is maternal duplication of 11p15 associated with Silver-Russell syndrome?

Background: Silver-Russell syndrome (SRS) is a heterogeneous malformation syndrome characterised by intrauterine and postnatal growth retardation (IUGR, PGR) and dysmorphisms. The basic causes are unknown, however in approximately 10% of patients a maternal uniparental disomy (UPD) of chromosome 7 or chromosomal aberrations can be detected. Four growth retarded children, two with SRS-like features, associated with maternal duplications of 11p15 have been described. Considering the involvement of this genomic region in Beckwith-Wiedemann overgrowth syndrome (BWS), we postulated that some cases of SRS—with an opposite phenotype to BWS—might also be caused by genomic disturbances in 11p15.

Methods: A total of 46 SRS patients were screened for genomic rearrangements in 11p15 by STR typing and FISH analysis.

Results: Two SRS patients with duplications of maternal 11p material in our study population (n = 46) were detected. In patient SR46, the duplicated region covered at least 9 Mb; FISH analysis revealed a translocation of 11p15 onto 10q. In patient SR90, additional 11p15 material (approximately 5 Mb) was translocated to the short arm of chromosome 15.

Conclusions: We suggest that diagnostic testing for duplication in 11p15 should be offered to patients with severe IUGR and PGR with clinical signs reminiscent of SRS. SRS is a genetically heterogeneous condition and patients with a maternal duplication of 11p15.5 may form an important subgroup.

     

Genetic testing in the evaluation of individuals with clinical diagnosis of atypical Sturge–Weber syndrome

Sturge–Weber Syndrome (SWS) is a rare vascular malformation disorder characterized by abnormal blood vessels in the brain, skin, and eye. SWS is most commonly caused by a somatic mosaic GNAQ-p.Arg183Gln variant. In this series, 12 patients presented for clinical evaluation of SWS but were noted to have atypical features, and therefore germline and/or somatic genetic testing was performed. Atypical features included extensive capillary malformation on the body as well as the face, frontal bossing, macrocephaly, telangiectasia, overgrowth of extremities, absence of neurologic signs and symptoms, and family history of vascular malformations. Five patients had a somatic GNAQ or GNA11 pathogenic variant, one patient had a somatic mosaic likely-pathogenic variant in PIK3CA, and another one had a somatic mosaic deletion that disrupted PTPRD. The other five patients had germline variants in RASA1, EPHB4, or KIT. Our findings suggest that patients presenting for SWS evaluation who have atypical clinical characteristics may have pathogenic germline or somatic variants in genes other than GNAQ or GNA11. Broad germline and somatic genetic testing in these patients with atypical findings may have implications for medical care, prognosis, and trial eligibility.     

A newborn with a 790 kb chromosome 17p13.3 microduplication presenting with aortic stenosis,microcephaly and dysmorphic facial features - Is cardiac assessment necessary for all patients with 17p13.3 microduplication?

While deletion of chromosome 17p13.3 (encompassing PAFAH1B1 and YWHAE genes) is known to result in Miller–Dieker syndrome (OMIM 247200), 17p13.3 microduplication gives rise to a condition commonly associated with developmental delay and autism spectrum disorder. We report a Chinese newborn presenting with dysmorphic features, microcephaly and valvar aortic stenosis, who was confirmed to have a 790 kb microduplication in chromosome 17p13.3 by array comparative genomic hybridization (aCGH). The patient passed away at 4 months of age with presumably life-threatening event associated with his cardiac condition. From literature review, congenital heart diseases of various kinds were identified in up to 20% of patients with 17p13.3 microduplication. We propose cardiac assessment should be part of the comprehensive evaluation of these patients.     

Enterovirus determination in cases with a diagnosis of the Guillain-Barré syndrome by using the acid-concentration technic

The purpose of this work was to detect enteroviruses in feces by an acid concentration technique (ACT). Fifty-eight samples from children less than 5 years age with diagnosis of Guillain-Barré syndrome (GBS) were analyzed using the routine technique and ACT. Nine positive samples with the routine technique were used as controls. Nine control samples and 22 additional (31 cases) non-polio enteroviruses were isolated and identified with the ACT (53%). Thus, 38% more isolates were obtained by ACT. Isolation was more successful in the RD cellular line (59%) than in Hep-2c (41%). In most cases most titers (71%) obtained were low. ACT improved the detection of enteroviruses but because it is very expensive and laborious, it should be used in the case of laboratories that analyze multiple samples, for special cases such as with autopsy cases and when results are compatible to poliovirus using the routine technique and only in samples obtained during the first 15 days of symptomatology.     

790 Kb microduplication in chromosome band 17p13.1 associated with intellectual disability, afebrile seizures, dysmorphic features, diabetes, and hypothyroidism

We report a patient with a moderate mental retardation, afebrile seizure, mild dysmorphic features and type 2 diabetes mellitus with mild obesity and metabolic syndrome. Array-CGH analysis revealed a de novo 790–830 kb duplication on chromosome 17p13.1, not reported so far. Among the approximately 50 genes involved in the rearrangement, neuroligin 2 (NLGN2) and ephrin B3 (EFNB3) are candidates for the mental retardation phenotype. NLGN2 may therefore be a novel candidate gene for mental retardation or autistic spectrum disorder, joining other members of the neurexin/neuroligin network. Moreover, GLUT4, a member of the solute carrier family 2, may play a role in the patient’s type 2 diabetes.     

Interstitial deletion of 6q25.2�Cq25.3: a novel microdeletion syndrome associated with microcephaly, developmental delay, dysmorphic features and hearing loss

Interstitial deletions of 6q are rare. We report a detailed clinical and molecular characterization of four patients with interstitial deletion involving 6q25. All of our patients presented with microcephaly, developmental delay, dysmorphic features and hearing loss, whereas two of them had agenesis of the corpus callosum. We determined the size, extent and genomic content of the deletions using high-density array-comparative genomic hybridization (a-CGH), and found that a common segment spanning 3.52 Mb within the 6q25.2–q25.3 region was deleted in all four cases. We hypothesize that a subset of genes in the commonly deleted region are dosage sensitive and that haploinsufficieny of these genes impairs normal development of the brain and hearing.     

Mosaicism for maternal uniparental disomy 15 in a boy with some clinical features of Prader–Willi syndrome

Prader–Willi syndrome (PWS) is caused by the lack of paternal expression of imprinted genes in the human chromosomal region 15q11.2–q13.2, which can be due to an interstitial deletion at 15q11.2–q13 of paternal origin (65–75%), maternal uniparental disomy (matUPD) of chromosome 15 (20–30%), or an imprinting defect (1–3%). The majority of PWS-associated matUPD15 cases represent a complete heterodisomy of chromosome 15 or a mixture of hetero- and isodisomic regions across the chromosome 15. Pure maternal isodisomy is observed in only a few matUPD15 patients. Here we report a case of an 18-year-old boy with some clinical features of Prader–Willi syndrome, such as overweight, muscular hypotonia, facial dysmorphism and psychiatric problems, but there was no reason to suspect PWS in the patient based solely on the phenotype estimation. However, chromosomal microarray analysis (CMA) revealed mosaic loss of heterozygosity of the entire chromosome 15. Methylation-specific multiplex ligation-dependant probe amplification (MS-MLPA) analysis showed hypermethylation of the SNRPN and NDN genes in the PWS/AS critical region of chromosome 15 in this patient. Taking into consideration the MS-MLPA results and the presence of PWS features in the patient, we concluded that it was matUPD15, although the patient's parents were not enrolled in the study. According to CMA and karyotyping, no trisomic or monosomic cells were present. To the best of our knowledge, only two PWS cases with mosaic maternal isodisomy 15 and without trisomic/monosomic cell lines have been reported so far.     

A diagnosis of Birt–Hogg–Dubé syndrome in individuals with Smith–Magenis syndrome: Recommendation for cancer screening

We report a series of four unrelated adults with Smith–Magenis syndrome (SMS) and concomitant features of Birt–Hogg–Dubé (BHD) syndrome based upon haploinsufficiency for FLCN and characteristic renal cell carcinomas and/or evidence of cutaneous fibrofolliculomas. Three of the cases constitute the first known association of histopathologically verified characteristic BHD-associated renal tumors in adults with SMS; the fourth was identified to have histologically confirmed skin fibrofolliculomas. Molecular analysis documented second-hit FLCN mutations in two of the three cases with confirmed BHD renal pathology. These cases suggest the need to expand management recommendations for SMS to include kidney cancer surveillance starting at 20 years of age, as per the screening recommendations for BHD syndrome.     

Dementia in a woman with Prader–Willi syndrome

We report on a 58-year-old woman with Prader–Willi syndrome (PWS) and dementia.This case report illustrates a new research area in older adults with PWS. Dementia might be associated with PWS. In the case of dementia, more clinical studies are warranted to observe whether premature Alzheimer changes or indications of other dementia forms indeed occur more prevalent in people with PWS.     

Improvements in population-based survival of patients presenting with metastatic rectal cancer in the south of the Netherlands, 1992–2008

We analysed population-based treatment and survival data of patients who presented with metastatic rectal cancer. All patients diagnosed with primary synchronous metastatic rectal cancer between 1992 and 2008 in the Eindhoven Cancer Registry area were included. Date of diagnosis was divided into three periods (1992–1999, 2000–2004, 2005–2008) according to the availability of chemotherapy type. We assessed treatment patterns and overall survival according to period of diagnosis. The proportion of patients diagnosed with stage IV disease increased from 16% in 1992–1999 to 20% in 2005–2008 (P < 0.0001). Chemotherapy use increased from 5% in 1992 to 61% in 2008 (P < 0.0001). Resection rates of the primary tumour decreased from 65% in 1992 to 27% in 2008 (P < 0.0001), while metastasectomy rates remained constant since 1999 (9%). Median survival increased from 38 weeks (95% confidence interval (CI) 32–44) in 1992–1999 to 53 weeks (95% CI 48–61) in 2005–2008. Among patients not receiving chemotherapy median survival remained approximately 30 weeks. Multivariable analysis confirmed the lower risk of death among patients diagnosed in more recent years. Increased use of chemotherapy went together with improved median survival among patients with metastatic rectal cancer in the last two decades. Stage migration as an effect of more effective imaging procedures is likely to be partly responsible for this improved survival.     

An unusual self-limited clonal Mott cell proliferation with lymphoplasmacytic lymphoma-like features in a child with the Wiskott–Aldrich syndrome and Von Recklinghausen's neurofibromatosis

Patients with the Wiskott–Aldrich syndrome are at high risk for development of lymphomas, which are predominantly extranodal and of the immunoblastic type. We present a case of a self-limited lymphoproliferation with features of lymphoplasmacytic lymphoma arising in a patient with the Wiskott–Aldrich syndrome. The patient also had stigmata of von Recklinghausen's neurofibromatosis. The tumor was composed of CD138+, IgGκ+, CD20−, PAX-5− Mott cells and CD5−, CD10−, CD19+, CD20+, CD43− small lymphoid B-cells that partially expressed CD23.     

Identification of the first deep intronic mutation in the RPS6KA3 gene in a patient with a severe form of Coffin–Lowry syndrome

Coffin–Lowry syndrome (CLS) is an X-linked disorder characterized by growth and psychomotor retardation, hypotonia and progressive skeletal changes. RPS6KA3 is the only gene known to be associated with CLS, and over 150 distinct inactivating mutations in this gene have so far been reported in CLS patients. However, no defect is found in about half of the CLS compatible patients by exon sequencing. We report here the first deep intronic mutation in RPS6KA3, which is associated with the retention of intronic sequences in the mRNAs. Indeed, this finding suggests that all the patients with a highly suggestive CLS clinical diagnosis, but in whom exon screening has failed to detect a mutation, should be reanalyzed at the RNA level.     

Nine patients with a microdeletion 15q11.2 between breakpoints 1 and 2 of the Prader–Willi critical region,possibly associated with behavioural disturbances

Behavioural differences have been described in patients with type I deletions (between breakpoints 1 and 3 (BP1–BP3)) or type II deletions (between breakpoints 2 and 3) of the 15q11.2 Prader–Willi/Angelman region. The larger type I deletions appear to coincide with more severe behavioural problems (autism, ADHD, obsessive–compulsive disorder). The non-imprinted chromosomal segment between breakpoints 1 and 2 involves four highly conserved genes, TUBGCP5, NIPA1, NIPA2, and CYFIP1; the latter three are widely expressed in the central nervous system, while TUBGCP5 is expressed in the subthalamic nuclei. These genes might explain the more severe behavioural problems seen in type I deletions.We describe nine cases with a microdeletion at 15q11.2 between BP1–BP2, thus having a haploinsufficiency for TUBGCP5, NIPA1, NIPA2, and CYFIP1 without Prader–Willi/Angelman syndrome. The clinical significance of a pure BP1–BP2 microdeletion has been debated, however, our patients shared several clinical features, including delayed motor and speech development, dysmorphisms and behavioural problems (ADHD, autism, obsessive–compulsive behaviour). Although the deletion often appeared to be inherited from a normal or mildly affected parent, it was de novo in two cases and we did not find it in 350 healthy unrelated controls.Our results suggest a pathogenic nature for the BP1–BP2 microdeletion and, although there obviously is an incomplete penetrance, they support the existence of a novel microdeletion syndrome in 15q11.2.