Hip displacement in Wolf-Hirschhorn syndrome: Report on three cases and review of associated musculoskeletal pathologies.

Wolf-Hirschhorn syndrome is a rare genetic disease caused by a chromosomal deletion of the distal short arm of Chromosome 4. It is associated with multisystem abnormalities, including delayed growth, characteristic facial features, epilepsy, and skeletal abnormalities. We report three patients who developed hip displacement, and describe the occurrence of delayed and nonunion in patients who underwent corrective proximal femoral osteotomy for hip displacement. We also performed a literature review identifying common musculoskeletal presentations associated with the condition. Patients with Wolf-Hirschhorn Syndrome are at risk of hip displacement (subluxation), and we would advocate annual hip surveillance in this patient group.

De novo truncating variant in NSD2gene leading to atypical Wolf-Hirschhorn syndrome phenotype.

BACKGROUND: Wolf-Hirschhorn syndrome (WHS) is a contiguous gene syndrome caused by partial 4p deletion highly variable in size in individual patients. The core WHS phenotype is defined by the association of growth delay, typical facial characteristics, intellectual disability and seizures. The WHS critical region (WHSCR) has been narrowed down and NSD2 falls within this 200 kb region. Only four patients with NSD2 variants have been documented with phenotypic features in detail. CASE PRESENTATION: Herein, we report the case of a 12-year-old boy with developmental delay. He had dysmorphic facial features including wide-spaced eyes, prominent nasal bridge continuing to forehead, abnormal teething and micrognathia. He also had mild clinodactyly of both hands. Using whole-exome sequencing, we identified a pathogenic mutation in NSD2 [c.4029_4030insAA, p.Glu1344Lysfs*49] isolated from peripheral blood DNA. Sanger confirmation of this variant revealed it as a de novo truncating variant in the family. CONCLUSION: Here, we reported a boy with de novo truncating variant in NSD2 with atypical clinical features comparing with 4p16.3 deletion related WHS. Our finding further supported the pathogenesis of truncating variants in NSD2 and delineated the possible symptom spectrum caused by these variants.

Oligonephronia and Wolf-Hirschhorn syndrome: A further observation.

Wolf-Hirschhorn syndrome (WHS) is a rare chromosomal disorder caused by a partial deletion of chromosome 4 (4p16.3p16.2). We describe a case of a male 9 years old children with WHS proteinuria and hypertension. Laboratory data showed creatinine 1.05 mg/dl, GFR 65.9 ml/min/1.73 m2 , cholesterol 280 mg/dl, triglyceride 125 mg/dl with electrolytes in the normal range. Urine collection showed protein 2.72 g/L with a urine protein/creatinine ratio (UP /UCr ratio) of 4.2 and diuresis of 1,100 ml. Renal ultrasound showed reduced kidney dimensions with diffusely hyperechogenic cortex and poorly visualized pyramids. Renal biopsy showed oligonephronia with focal segmental glomerulosclerosis associated with initial tubulointerstitial sclerotic atrophy. The child began therapy with Angiotensin-converting enzyme inhibitors (ACE-inhibitors) to reduce proteinuria and progression of chronic kidney disease. In the literature the anomalies of number of glomeruli oligonephronia and oligomeganephronia (OMN) are described in two forms, one without any associated anomalies, sporadic, and solitary and the other with one or more anomalies. Our review of the literature shows that the pathogenesis of this anomaly is unknown but the role of chromosome 4 is very relevant. Many cases of OMN are associated with anomalies on this chromosome, in the literature cases series we observed this association in 14/48 cases (29.2%) and in 7 of these 14 cases with WHS. Our case and the review of literature demonstrate how periodic urinalysis and renal ultrasound monitoring is recommended in patients affected by WHS and the renal biopsy must be performed when there is the onset of proteinuria.

De novo unbalanced translocation (4p duplication/8p deletion) in a patient with autism, OCD, and overgrowth syndrome.

Chromosomal abnormalities, such as unbalanced translocations and copy number variants (CNVs), are found in autism spectrum disorders (ASDs) [Sanders et al. (2011) Neuron 70: 863-885]. Many chromosomal abnormalities, including sub microscopic genomic deletions and duplications, are missed by G-banded karyotyping or Fragile X screening alone and are picked up by chromosomal microarrays [Shen et al. (2010) Pediatrics 125: e727-735]. Translocations involving chromosomes 4 and 8 are possibly the second most frequent translocation in humans and are often undetected in routine cytogenetics [Giglio et al. (2002) Circulation 102: 432-437]. Deletions of 4p16 have been associated with Wolf-Hirschhorn syndrome while 4p16 duplications have been associated with an overgrowth syndrome and mild to moderate mental retardation [Partington et al. (1997) Journal of Medical Genetics 34: 719-728]. The 8p23.3 region contains the autism candidate gene DLGAP2, which can contribute to autism when disrupted [Marshall et al. (2008) The American Journal of Human Genetics 82: 477-488] . There has been a case report of a family with autism spectrum disorder (ASD), prominent obsessional behavior, and overgrowth in patients with der (8) t (4;8) p (16;23) [Partington et al. (1997)]. This is an independent report of a male patient with autism, obsessive compulsive disorder (OCD), attention-deficit hyperactivity disorder (ADHD), and an overgrowth syndrome, whose de novo unbalanced translocation der (8) t (4;8) p (16.1→ter; 23.1→ter) was initially missed by routine cytogenetics but detected with SNP microarray, allowing higher resolution of translocation breakpoints.

Successful treatment of migrating partial seizures in Wolf-Hirschhorn syndrome with bromide.

A girl with mild psychomotor developmental delay developed right or left hemiclonic convulsion at 10months of age. One month later, clusters of hemiclonic or bilateral tonic seizures with eyelid twitching emerged, resulting in status epilepticus. Treatment with phenobarbital and potassium bromide completely terminated the seizures within 10days. Ictal electroencephalography revealed a migrating focus of rhythmic 3-4Hz waves from the right temporal to right frontal regions and then to the left frontal regions. Genetic analysis was conducted based on the characteristic facial appearance of the patient, which identified a 2.1-Mb terminal deletion on chromosome 4p. This is the first case of Wolf-Hirschhorn syndrome complicated by epilepsy with migrating partial seizures.

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.

Developmental trajectories in syndromes with intellectual disability, with a focus on Wolf-Hirschhorn and its cognitive-behavioral profile.

Few studies exist of developmental trajectories in children with intellectual disability, and none for those with subtelomeric deletions. We compared developmental trajectories of children with Wolf-Hirschhorn syndrome to other genetic disorders. We recruited 106 children diagnosed with fragile X, Williams-Beuren syndrome, or Wolf-Hirschhorn syndrome, assessing their intellectual and adaptive behavior abilities. We retested 61 children 2 years later. We compared Time 1 and Time 2 difference scores related to genetic disorder, age, initial IQ, or adaptive behavior composite. Results show genetic disorder and initial IQ score were significant factors for IQ differences, but only genetic disorder affected adaptive behavior differences. Results suggest different gene-brain-behavior pathways likely exist for these genetic disorders. Different developmental trajectories will influence the type and intensity of intervention implemented by caregivers.

Cognitive-behavioral features of Wolf-Hirschhorn syndrome and other subtelomeric microdeletions.

Wolf-Hirschhorn syndrome (WHS) is a complex congenital malformation produced by a loss of genomic material at the locus 4p16.3. In addition to its dysmorphic features, the deletion produces a range of intellectual disability (ID). Many clinical aspects of WHS are well-characterized; however, the cognitive-behavioral characteristics have been rarely examined in a systematic fashion. The purpose of our study was to examine the cognitive-behavioral features of WHS and to compare them to children with other subtelomeric deletions that also produce ID. We recruited 45 children with subtelomeric deletions and examined their cognitive-behavioral abilities using a neuropsychological assessment battery composed of standardized instruments. Nineteen children were diagnosed with WHS and 26 children with one of three other subtelomeric deletions-11q25 (Jacobsen syndrome), deletion 2q37, and inversion duplication deletion 8p21-23. We found children with WHS to be more severely impacted cognitively than children from any of the other groups. Their overall adaptive behavior was lower as well. However, children with WHS exhibit strengths in socialization skills comparable to the levels attained by the other groups we assessed. Importantly, the proportion of children with WHS with autism or autistic-like features is significantly lower than the rates of autism found in the other subtelomeric disorders we examined.

Wolf-Hirschhorn syndrome with improvement of renal function.

Wolf-Hirschhorn syndrome (WHS) is a chromosomal disorder characterized by partial deletion of the short arm of chromosome 4. We describe a girl with a de novo unbalanced traslocation t(4;7)(p16.2;p22), associated with a mild version of a classical WHS phenotype. She did not present major urinary tract abnormalities but had parenchymal hyperechogenicity at renal ultrasound at the birth with normal renal scintigraphy. She had also a reduction of GFR with elevated levels of blood urea nitrogen and serum potassium until the age of 6 months. We followed the patient with periodic clinical examination and laboratory and radiological investigations and observed at the age of 5 years a normal renal ultrasound without parenchymal hyperechogenicity.

Spectrum of epilepsy and electroencephalogram patterns in Wolf-Hirschhorn syndrome: experience with 87 patients.

To define the spectrum of epilepsy in Wolf-Hirschhorn syndrome (WHS) better, we studied 87 patients (54 females, 33 males; median age 5.6 years; age range 1-25.6 years) with confirmed 4p16.3 deletion. On the basis of clinical charts, we retrospectively analyzed the evolution of the electroencephalogram (EEG) findings and seizures. Epilepsy occurred in 81 patients (93%) within the first 3 years of life. Sixty out of 81 (74%) had generalized tonic-clonic seizures, which was the only seizure pattern in 32. Tonic spasms occurred in 15 out of 81 (18%), complex partial seizures in 10 out of 81 (12%), and clonic seizures in 6 out of 81 (7%). Seizures were frequently triggered by fever (59 out of 81; 73%), and occurred in clusters in 36 out of 72 (50%). In the same 36 (50%), unilateral or generalized clonic or tonic-clonic status epilepticus occurred during the first 3 years of life. Twenty-seven out of 81 patients (33%) developed atypical absences between 1 and 6 years, accompanied by a myoclonic component involving the eyelids and the hands. Distinctive EEG abnormalities were observed in 73 out of 81 (90%). Epilepsy was well controlled in 65 out of 81 (81%), mainly with valproate and phenobarbital, and improved with age in all. Thirty-two out of 58 (55%) are currently seizure-free. Seizures stopped at a median age of 4 years 6 months. Epilepsy represents a major clinical challenge in WHS; however, it has a good prognosis. Early diagnosis and treatment of atypical absences, subtle and often misdiagnosed, is mandatory.

Pathophysiology of mitochondrial volume homeostasis: potassium transport and permeability transition.

Regulation of mitochondrial volume is a key issue in cellular pathophysiology. Mitochondrial volume and shape changes can occur following regulated fission-fusion events, which are modulated by a complex network of cytosolic and mitochondrial proteins; and through regulation of ion transport across the inner membrane. In this review we will cover mitochondrial volume homeostasis that depends on (i) monovalent cation transport across the inner membrane, a regulated process that couples electrophoretic K(+) influx on K(+) channels to K(+) extrusion through the K(+)-H(+) exchanger; (ii) the permeability transition, a loss of inner membrane permeability that may be instrumental in triggering cell death. Specific emphasis will be placed on molecular advances on the nature of the transport protein(s) involved, and/or on diseases that depend on mitochondrial volume dysregulation.