Clinical details of individuals with Rauch-Steindl syndrome due to NSD2 truncating variants.

BACKGROUND: Rauch-Steindl syndrome (RAUST) is a very rare genetic syndrome caused by a pathogenic variant in NSD2 on chromosome 4p16.3. Although NSD2 was previously thought to be the major gene in Wolf-Hirschhorn syndrome (WHS), a contiguous gene syndrome of chromosome 4p16.3 deletion, RAUST has been found to present different facial and clinical features from WHS. In this study, we report the details of two newly diagnosed individuals with RAUST in order to better understand the molecular and clinical features of RAUST. METHODS: Whole-genome sequencing was performed on two individuals with psychomotor delay and growth failure. Detailed clinical evaluation of growth parameters, craniofacial features, electroencephalogram (EEG), magnetic resonance imaging of the brain, and developmental assessment were performed. RESULTS: Both individuals had de novo truncating variants in NSD2. One had a novel variant (c.2470C>T, p.Arg824*), and the other had a recurrent variant (c.4028del, p.Pro1343Glnfs*49). Both exhibited characteristic RAUST facial features, growth failure, and mild psychomotor delay. A novel finding of RAUST was seen in individual 2, a Chiari malformation type 1, and both showed delayed bone age. They lacked common WHS features such as congenital heart defects, cleft lip/palate, and seizures (EEG with abnormal findings). CONCLUSION: We present a novel variant and clinical presentations of RAUST, expand the molecular and clinical diversity of RAUST, and improve our understanding of this rare syndrome, which is distinct from WHS. Further researches are needed on more RAUST cases and on functional analysis of NSD2.

Natural history study of adults with Wolf-Hirschhorn syndrome 2: Patient-reported outcomes study.

Wolf-Hirschhorn syndrome (WHS) is a contiguous gene disorder consisting of prenatal and postnatal growth deficiency, distinctive craniofacial features, intellectual disability, and seizures. The condition is caused by a partial loss of material from the distal portion of the short arm of chromosome 4 (4p16.3). While there are many reports of individuals with WHS, useful data on long-term survival and life status of adults with the syndrome are very limited. There are only 11 reports of individuals over the age of 18 years in the literature. Establishing the medical manifestations of adults with WHS would be helpful in establishing appropriate health supervision guidelines. This study was one component of a two-part investigation on adults with WHS. This patient-reported outcomes study (PROS) was accomplished by using the registry of rare diseases at Sanford Research, Coordination of Rare Diseases (CoRDS)at Sanford. Thirty family members or caretakers of 30 adults with WHS/4p- entered into the CoRDS registry and completed some or all of the survey data. Twelve caretakers completed the recently-added survey on activities of daily living. Two of the individuals with WHS were partly independent while 10 required total care. The results provide novel information on daily life and independence in adults with WHS. Importantly, the majority of caretakers reported that the adults were in good health. The data from both parts of the study will contribute to our knowledge of the natural history of the syndrome and guide in establishing appropriate health supervision guidelines for adults with WHS.

The delineation of the Wolf-Hirschhorn syndrome over six decades: Illustration of the ongoing advances in phenotype analysis and cytogenomic technology.

Since Hirschhorn's description in 1961, the history and chronology of the clinical, cytogenetic, and molecular characterization of Wolf-Hirschhorn syndrome (WHS) elegantly demonstrates the remarkable advances in genetic technology over the last six decades that have paralleled the delineation of the phenotype. After mention in the Human Chromosome Newsletter of a child with a visible deletion of the top of a B chromosome group, 4-5, Hirschhorn and colleagues companioned their report with that of Wolf et al. in Humangenetik in 1965, and the condition was recognized and named. The 1960-1970s witnessed the description of many of the now classic chromosome disorders, including WHS, while HRB allowed for the recognition of chromosome syndromes with smaller deletions/duplications. FISH probes, developed in the next two decades, enabled the characterization of the critical region of WHS and improved clinical diagnosis with subtelomeric probes. Cytogenomic microarray in the early-mid 2000s led to both improved diagnosis of WHS patients and documentation of microdeletions of <5 megabases, helping to characterize the critical regions for specific component phenotypes (e.g., seizures, face). Recently exome sequencing technology has led to the discovery of WHS patients with WHSC1 loss of function variants, displaying some cardinal features of the phenotype (face, growth, and developmental delay).

Natural history study of adults with Wolf-Hirschhorn syndrome 1: Case series of personally observed 35 individuals.

Wolf-Hirschhorn syndrome (WHS) is a contiguous gene disorder, clinically delineated by prenatal and postnatal growth deficiency, distinctive craniofacial features, intellectual disability, and seizures. The disorder is caused by partial loss of material from the distal portion of the short arm of chromosome 4 (4p16.3). Although more than 300 persons with WHS have been reported in the literature, there is sparse, if any, long-term follow-up of these individuals and thus little knowledge about course and potential further complications and health risks during adulthood and advanced age. This study attempted to assess medical conditions and function of adult individuals with WHS. It was one component of a two-part investigation on adults with WHS. The other part of the study is the patient-reported outcomes study reported elsewhere. About 35 individuals with WHS (26 females; nine males), aged between 19 and 55 years were recruited. About 25 individuals were personally observed at the IRCCS Stella Maris Foundation by A.B. and followed up between 5 and 20 years; and 10 were recruited from the 4p-Support Group, The United States. Of note, 23/35 (66%) are close to total care. About 11 out of 35 (31%) were partly self-independent, requiring supervision on certain daily routines, and 1 out of 35 (3%) was fully independent. However, a positive perspective is given by the overall good health enjoyed by the 66% of our cohort of individuals. Overall, quality of life and level of function into adulthood appear to be less critical than anticipated from previous studies.

Clinical and genetic characterization of ten Egyptian patients with Wolf-Hirschhorn syndrome and review of literature.

BACKGROUND: Wolf-Hirschhorn syndrome (WHS) (OMIM 194190) is a multiple congenital anomalies/intellectual disability syndrome. It is caused by partial loss of genetic material from the distal portion of the short arm of chromosome. METHODS: We studied the phenotype-genotype correlation. RESULTS: We present the clinical manifestations and cytogenetic results of 10 unrelated Egyptian patients with 4p deletions. Karyotyping, FISH and MLPA was performed for screening for microdeletion syndromes. Array CGH was done for two patients. All patients exhibited the cardinal clinical manifestation of WHS. FISH proved deletion of the specific WHS locus in all patients. MLPA detected microdeletion of the specific locus in two patients with normal karyotypes, while array CGH, performed for two patients, has delineated the extent of the deleted segments and the involved genes. LETM1, the main candidate gene for the seizure phenotype, was found deleted in the two patients tested by array CGH; nevertheless, one of them did not manifest seizures. The study emphasized the previous. CONCLUSION: WHS is a contiguous gene syndrome resulting from hemizygosity of the terminal 2 Mb of 4p16.3 region. The Branchial fistula, detected in one of our patients is a new finding that, to our knowledge, was not reported.

Wolf-Hirschhorn syndrome: A case series from India.

Wolf-Hirschhorn syndrome (WHS) (OMIM#194190) is a contiguous gene syndrome with estimated prevalence being around 1 in 50,000 births. The syndrome is caused by deletion of a critical region (Wolf-Hirschhorn Syndrome Critical region-WHSCR) on chromosome 4p16.3. Its core features are typical facial gestalt, growth retardation, intellectual disability, or developmental delay and seizures. We describe four patients, each highlighting a different aspect of this syndrome. One patient was detected by karyotype where a large deletion was identified. Three other children were diagnosed after targeted multiplex ligation-dependent probe amplification (MLPA) where heterozygous deletion of the probes on chromosome 4p16.3 were identified. One of these children additionally had heterozygous duplication of the probe for chromosome band 5p13.3. Less than half of the patients can be identified by conventional cytogenetics and molecular cytogenetic testing should be offered for diagnosis. Karyotyping of the parents should always be offered in a child with WHS.

De novo truncating variants in WHSC1 recapitulate the Wolf-Hirschhorn (4p16.3 microdeletion) syndrome phenotype.

PURPOSE: Wolf-Hirschhorn syndrome (WHS) is a genomic disorder with a recognizable dysmorphology profile caused by hemizygosity at 4p16.3. Previous attempts have failed to map the minimal critical locus to a single gene, leaving open the possibility that the core phenotypic components of the syndrome are caused by the combined haploinsufficiency of multiple genes. METHODS: Clinical exome sequencing and "reverse" phenotyping. RESULTS: We identified two patients with de novo truncating variants in WHSC1, which maps to the WHS critical locus. The phenotype of these two individuals is consistent with WHS, which suggests that haploinsufficiency of WHSC1 is sufficient to recapitulate the core phenotype (characteristic facies, and growth and developmental delay) of this classic microdeletion syndrome. CONCLUSION: Our study expands the list of microdeletion syndromes that are solved at the single-gene level, and establishes WHSC1 as a disease gene in humans. Given the severe nature of the reported variants, the full phenotypic expression of WHSC1 may be further expanded by future reports of milder variants.

LETM1 couples mitochondrial DNA metabolism and nutrient preference.

The diverse clinical phenotypes of Wolf-Hirschhorn syndrome (WHS) are the result of haploinsufficiency of several genes, one of which, LETM1, encodes a protein of the mitochondrial inner membrane of uncertain function. Here, we show that LETM1 is associated with mitochondrial ribosomes, is required for mitochondrial DNA distribution and expression, and regulates the activity of an ancillary metabolic enzyme, pyruvate dehydrogenase. LETM1 deficiency in WHS alters mitochondrial morphology and DNA organization, as does substituting ketone bodies for glucose in control cells. While this change in nutrient availability leads to the death of fibroblasts with normal amounts of LETM1, WHS-derived fibroblasts survive on ketone bodies, which can be attributed to their reduced dependence on glucose oxidation. Thus, remodeling of mitochondrial nucleoprotein complexes results from the inability of mitochondria to use specific substrates for energy production and is indicative of mitochondrial dysfunction. However, the dysfunction could be mitigated by a modified diet-for WHS, one high in lipids and low in carbohydrates.

Prenatal diagnosis of Wolf-Hirschhorn syndrome: from ultrasound findings, diagnostic technology to genetic counseling.

PURPOSE: Wolf-Hirschhorn syndrome (WHS) is a contiguous gene syndrome due to terminal chromosome 4p deletions. We explored prenatal diagnosis of WHS by ultrasound as well as karyotype and single nucleotide polymorphism array (SNP array) to characterize the structural variants of WHS prenatally. METHODS: Ten prenatal cases of WHS were evaluated for the indication of the invasive testing, the ultrasound features, and cytogenetic and microarray results. RESULTS: Eight cases were diagnosed by karyotyping and SNP array, while two cases were detected only by SNP array. Combining our cases with 37 prenatal cases from the literature, the most common sonographic features were IUGR (97.7%) and typical facial appearance (82.9%). Other less common phenotypes included renal hypoplasia (36.2%), cardiac malformation (29.8%), cleft lip and palate (25.5%), cerebral abnormalities (25.5%), skeletal anomalies (21.3%), and increased nuchal translucency/nuchal fold thickness (NT/NF) (19%). CONCLUSIONS: The most common intrauterine phenotypes of WHS were severe IUGR and typical facial appearance with other less consistent ultrasound findings. Noninvasive prenatal testing (NIPT) is one very promising screening tool for WHS. SNP array can improve diagnostic precision for detecting WHS, especially for the cryptic aberrations that cannot be identified by the traditional karyotyping. Ectopic kidney may be a previously unrecognized phenotype of WHS.

Exploring the developmental mechanisms underlying Wolf-Hirschhorn Syndrome: Evidence for defects in neural crest cell migration.

Wolf-Hirschhorn Syndrome (WHS) is a neurodevelopmental disorder characterized by mental retardation, craniofacial malformation, and defects in skeletal and heart development. The syndrome is associated with irregularities on the short arm of chromosome 4, including deletions of varying sizes and microduplications. Many of these genotypic aberrations in humans have been correlated with the classic WHS phenotype, and animal models have provided a context for mapping these genetic irregularities to specific phenotypes; however, there remains a significant knowledge gap concerning the cell biological mechanisms underlying these phenotypes. This review summarizes literature that has made recent contributions to this topic, drawing from the vast body of knowledge detailing the genetic particularities of the disorder and the more limited pool of information on its cell biology. Finally, we propose a novel characterization for WHS as a pathophysiology owing in part to defects in neural crest cell motility and migration during development.

Chromosomal microarray testing identifies a 4p terminal region associated with seizures in Wolf-Hirschhorn syndrome.

BACKGROUND: Wolf-Hirschhorn syndrome (WHS) is a contiguous gene deletion syndrome involving variable size deletions of the 4p16.3 region. Seizures are frequently, but not always, associated with WHS. We hypothesised that the size and location of the deleted region may correlate with seizure presentation. METHODS: Using chromosomal microarray analysis, we finely mapped the breakpoints of copy number variants (CNVs) in 48 individuals with WHS. Seizure phenotype data were collected through parent-reported answers to a comprehensive questionnaire and supplemented with available medical records. RESULTS: We observed a significant correlation between the presence of an interstitial 4p deletion and lack of a seizure phenotype (Fisher's exact test p=3.59e-6). In our cohort, there were five individuals with interstitial deletions with a distal breakpoint at least 751 kbp proximal to the 4p terminus. Four of these individuals have never had an observable seizure, and the fifth individual had a single febrile seizure at the age of 1.5 years. All other individuals in our cohort whose deletions encompass the terminal 751 kbp region report having seizures typical of WHS. Additional examples from the literature corroborate these observations and further refine the candidate seizure susceptibility region to a region 197 kbp in size, starting 368 kbp from the terminus of chromosome 4. CONCLUSIONS: We identify a small terminal region of chromosome 4p that represents a seizure susceptibility region. Deletion of this region in the context of WHS is sufficient for seizure occurrence.

Meiotic and pedigree segregation analyses in carriers of t(4;8)(p16;p23.1) differing in localization of breakpoint positions at 4p subband 4p16.3 and 4p16.1.

PURPOSE: The purpose of this study was to compare meiotic segregation in sperm cells from two carriers with t(4;8)(p16;p23.1) reciprocal chromosome translocations (RCTs), differing in localization of the breakpoint positions at the 4p subband-namely, 4p16.3 (carrier 1) and 4p16.1 (carrier 2)-and to compare data of the pedigree analyses performed by direct method. METHODS: Three-color fluorescent in situ hybridization (FISH) on sperm cells and FISH mapping for the evaluation of the breakpoint positions, data from pedigrees, and direct segregation analysis of the pedigrees were performed. RESULTS: Similar proportions of normal/balanced and unbalanced sperm cells were found in both carriers. The most common was an alternate type of segregation (about 52 % and about 48 %, respectively). Unbalanced adjacent I and adjacent II karyotypes were found in similar proportions about 15 %. The direct segregation analysis (following Stengel-Rutkowski) of the pedigree of carriers of t(4;8)(p16.1;p23.1) was performed and results were compared with the data of the pedigree segregation analysis obtained earlier through the indirect method. The probability of live-born progeny with unbalanced karyotype for carriers of t(4;8)(p16.1;p23.1) was moderately high at 18.8 %-comparable to the value obtained using the indirect method for the same carriership, which was 12 %. This was, however, markedly lower than the value of 41.2 % obtained through the pedigree segregation indirect analysis estimated for carriers of t(4;8)(p16.3;p23.1), perhaps due to the unique composition of genes present within the 4p16.1-4p 16.3 region. CONCLUSIONS: Revealed differences in pedigree segregation analysis did not correspond to the very similar profile of meiotic segregation patterns presented by carrier 1 and carrier 2. Most probably, such discordances may be due to differences in embryo survival rates arising from different genetic backgrounds.

LETM1 haploinsufficiency causes mitochondrial defects in cells from humans with Wolf-Hirschhorn syndrome: implications for dissecting the underlying pathomechanisms in this condition.

Wolf-Hirschhorn syndrome (WHS) represents an archetypical example of a contiguous gene deletion disorder - a condition comprising a complex set of developmental phenotypes with a multigenic origin. Epileptic seizures, intellectual disability, growth restriction, motor delay and hypotonia are major co-morbidities in WHS. Haploinsufficiency of LETM1, which encodes a mitochondrial inner-membrane protein functioning in ion transport, has been proposed as an underlying pathomechanism, principally for seizures but also for other core features of WHS, including growth and motor delay. Growing evidence derived from several model organisms suggests that reduced LETM1 expression is associated with some element of mitochondrial dysfunction. Surprisingly, LETM1-dependent mitochondrial functional deficits have not previously been described in cells from individuals with WHS. Here, using a unique panel of WHS-patient-derived cell lines with deletions of differing sizes, incorporating LETM1 or not, we show, for the first time, that LETM1 expression is reduced in mitochondria isolated from WHS-patient cells. Furthermore, we show that this is associated with distinct mitochondrial phenotypes, including altered intracellular [Ca(2+)] levels, dysfunctional mitochondrial transition-pore opening, hyperpolarization and superoxide leakage from resting mitochondria. Interestingly, we find that these phenotypes segregate with seizures in our WHS cohort. Our findings identify novel cellular phenotypes in WHS attributable to a 50% reduction in LETM1 expression level; these phenotypes could underlie and/or contribute to some of the core clinical features of this condition.

Clinical features in adult patient with Wolf-Hirschhorn syndrome.

The Wolf-Hirschhorn syndrome (WHS) encompasses deletions at the distal part of the short arm of one chromosome 4 (4p16 region). Clinical signs frequently include a typical facial appearance, mental retardation, intrauterine and postnatal growth retardation, hypotonia with decreased muscle bulk and seizures besides congenital heart malformations, midline defects, urinary tract malformations and brain, hearing and ophthalmologic malformations. Pathogenesis of WHS is multigenic and many factors are involved in prediction of prognosis such as extent of deletion, the occurrence of severe chromosome anomalies, the severe of seizures, the existence of serious internal, mainly cardiac, abnormalities and the degree of mental retardation. The phenotype of adult with WHS is in general similar to that of childhood being facial dysmorphism, growth retardation and mental retardation the rule in both adults and children. Avoid long-term complications and provide rehabilitation programs and genetic counseling may be essential in these patients.

RBPJ is disrupted in a case of proximal 4p deletion syndrome with epilepsy.

Proximal 4p deletion syndrome is characterized clinically by mental retardation, minor dysmorphic facial features, and is occasionally complicated with epilepsy. More than 20 cases of proximal 4p deletion syndrome have been reported, but the causative gene(s) remain elusive. We describe here a 2-year-old female patient with a common manifestation of proximal 4p deletion syndrome and infantile epileptic encephalopathy possessing a de novo balanced translocation t(4;13)(p15.2;q12.13). The patient was diagnosed as infantile spasms at 9 months of age. She presented with dysmorphic facial features and global developmental delay, compatible with proximal 4p deletion syndrome. Using fluorescence in situ hybridization, we determined the translocation breakpoint at 4p15.2 to be within RBPJ. RBPJ is a transcription factor in the Notch/RBPJ signaling pathway, playing a crucial role in the developing human brain, and particularly telencephalon development. Our findings, combined with those of previous studies, strongly suggest that RBPJ is causative for proximal 4p deletion syndrome and epilepsy in this case.

Prenatal ultrasound findings observed in the Wolf-Hirschhorn syndrome: data from the registry of congenital malformations in Auvergne.

BACKGROUND: Wolf-Hirschhorn syndrome (WHS) is associated with facial dysmorphism including high forehead, high nasal bridge, hypertelorism and severe mental retardation. WHS results from a 4p16.3 deletion. Only a small number of reports have been made on the prenatal ultrasound findings observed in WHS. CASES: Here we report our experience on 10 cases of WHS ascertained prenatally between 1983 and 2009 through the CEMC-Auvergne registry of congenital malformations. CONCLUSION: The assumption that a "Greek warrior helmet" facies is pathognomonic of WHS could lead to misdiagnosis. Other clinical findings such as severe and early onset intrauterine growth retardation, facial dysmorphism (high forehead, high nasal bridge, low-set ears, micrognathia, hypertelorism), atrial or ventricular septal defect, and renal dysplasia should help obstetricians to suspect the diagnosis of WHS prenatally.

Another patient with 12q13 microduplication.

Interstitial duplication of the long arm of chromosome 12 is a rare cytogenetic condition. While several reports describe distal 12q duplication, only one case report of homogeneous, non-mosaic interstitial 12q13 duplication has been documented to date. The authors of that observation proposed that the associated phenotype represented a phenocopy of Wolf-Hirschhorn syndrome [Dallapiccola et al., 2009]. Only a few other recorded patients with deletion 12q13 → 12q21 involved mosaicism. We describe a new patient with homogeneous 12q13 duplication in a 6-year-old girl who, in early infancy, presented with dysmorphic features suggesting Wolf-Hirschhorn syndrome. What is potentially significant about this patient is that her facial phenotype evolved with age, suggesting a different gestalt in older patients.

Diagnosis of familial Wolf-Hirschhorn syndrome due to a paternal cryptic chromosomal rearrangement by conventional and molecular cytogenetic techniques.

The use of conventional cytogenetic techniques in combination with fluorescent in situ hybridization (FISH) and single-nucleotide polymorphism (SNP) microarrays is necessary for the identification of cryptic rearrangements in the diagnosis of chromosomal syndromes. We report two siblings, a boy of 9 years and 9 months of age and his 7-years- and 5-month-old sister, with the classic Wolf-Hirschhorn syndrome (WHS) phenotype. Using high-resolution GTG- and NOR-banding karyotypes, as well as FISH analysis, we characterized a pure 4p deletion in both sibs and a balanced rearrangement in their father, consisting in an insertion of 4p material within a nucleolar organizing region of chromosome 15. Copy number variant (CNV) analysis using SNP arrays showed that both siblings have a similar size of 4p deletion (~6.5 Mb). Our results strongly support the need for conventional cytogenetic and FISH analysis, as well as high-density microarray mapping for the optimal characterization of the genetic imbalance in patients with WHS; parents must always be studied for recognizing cryptic balanced chromosomal rearrangements for an adequate genetic counseling.