wolf-hirschhorn syndrome (4p-): historic, cytogenetic, & medical aspects update on advances in...
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WOLF-HIRSCHHORN SYNDROME (4p-):WOLF-HIRSCHHORN SYNDROME (4p-):HISTORIC, CYTOGENETIC, HISTORIC, CYTOGENETIC,
& MEDICAL ASPECTS& MEDICAL ASPECTSUpdate On Advances In KnowledgeUpdate On Advances In Knowledge
John C. Carey, MDJohn C. Carey, MD Agatino Battaglia, MDAgatino Battaglia, MD University of UtahUniversity of Utah Stella Maris Institute forStella Maris Institute for
Division of Medical GeneticsDivision of Medical Genetics Child & Adolescent Child & Adolescent
Department of PediatricsDepartment of Pediatrics Neurology & Psychiatry Neurology & Psychiatry Salt Lake City, Utah Salt Lake City, Utah Pisa, Italy Pisa, Italy
Original PaperOriginal Paper• WHS is a MCA/DD disorder, first described by:
– Cooper H, Hirschhorn K. Apparent deletion of short arms of one chromosome (4 or 5) in a child with defects of midline fusion. Mammalian Chrom Nwsl 1961; 4: 14.
– Paper by Wolf et al. and Hirschhorn et al., Humangenetik, 1965
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• About 200 cases reported in literature
• Very little data on the natural history Pediatrics 1999, 103: 830-836
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• FREQUENCY 1/50,000 BIRTHS
• 2F : 1M SEX PREDILECTION
Exceeding 75% Greek warrior helmet appearance of the nose Microcephaly Hypertelorism Distinct Mouth Short philtrum Micrognathia Mental retardation IUGR/postnatal growth retardation Hypotonia Seizures Feeding difficulties Simple/angulated ears/pits/tags
Frequency of Main Characteristics of Wolf-Hirschhorn Syndrome
50% to 75% Distinctive EEG abnormalities Skeletal anomalies Abnormal teething Ptosis25% to 50% Heart defects Hearing defects Eye/optic nerve defect Stereotypies Cleft lip/palate Structural brain anomalies Genitourinary tract defectsBelow 25% Liver/gallbladder/gut/diaphragm anomalies
Frequency of Main Characteristics of Wolf-Hirschhorn Syndrome
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• Usually there tends to be a skewing of information to the negative.
• Families being told that their child has very little chance for meaningful interaction with relatives and peers; will never walk or achieve sphincter control.
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• To help delineate more accurately the natural history and to obtain better information to answer parents’ questions in a clinical setting, we collected information on >75 persons with WHS.
• Personally observed, or
• Clinical information gained from an exhaustive questionnaire sent out to the families through their national support groups in USA & Italy
(2000 – 2006).
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• 2 : 1 females to males
• Age range at first observation/question. filled out: newborn to 17 years
• 20 patients followed up by us from 4 months to 22 years
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Birth and Family History Data Birth and Family History Data
on 60 Patientson 60 Patients
• Family histories non-contributory
• Parental ages were similar to the general population
• Almost all patients (but one) were born at term and were small for dates
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• Age at diagnosis varied between 7 months gestation and 16 years
• Most patients had at least chromosome study before diagnosis was made
• Some patients with WHS are still being misdiagnosed and unrecognized
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• WHS is caused by deletion of the distal
portion of the short arm of chromosome
4 (the minimal deleted segment causing
the phenotype is 4p16.3)
• Regular G-banding 60%
• HRB 15%
• FISH 25% (using a probe that includes the WHCR)
Genetics of WHSGenetics of WHSDeletions involving 4p16.3 due to different types of
rearrangements:• Cytogenetically (microscopically) visible 4p deletion (~50-
60%)
p-arm
q-arm
deletion usually larger than 4 megabases (Mb)
Genetics of WHSGenetics of WHSDeletions involving 4p16.3 due to different types of
rearrangements:• Microdeletions (cannot be seen under the microscope)
detected by FISH using a probe for the WHS critical region (red) (~25-30%)
4
del(4)
deletion often between 2-4 Mb
WHS: cryptic deletions
Probe 190b4 (lef t) and probe 184d6 (right) deleted on one chromosome 4. Both probes identif y the WHS critical region in 4p16.3
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• If needed, subtelomeric FISH screening can be performed to determine if a deletion is the result of an unbalanced translocation
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• ~85% of patients have a “pure de novo deletion” (85% of paternal origin)
• ~15% patients have: “ring 4” or “4p-mosaicism”,
or “der 4” due to an unbalanced translocation
(in 2/3 mother carries the rearrangement)
• Parents of WHS should have cytogenetic analysis looking for a translocation or an inversion
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
• If a parent is a balanced translocation carrier, the risk to sibs of being affected with 4p monosomy (WHS) or 4p trisomy is
• The risk to the sibs of a proband is negligible if the deletion in the proband is de novo
• Prenatal testing (CVS or amniocentesis) is available if one parent is known to be a carrier of a chromosome rearrangement
AR. with WHS at
age 11 months
AR. with WHS at
age 11 months
Her boy-friend: age 8 months
Her boy-friend: age 8 months
Wolf-Hirschhorn (4p-) Syndrome:Wolf-Hirschhorn (4p-) Syndrome:Three Important ChallengesThree Important Challenges
• Feeding Difficulties
• Seizures
• Development Disability
Wolf-Hirschhorn (4p-) Syndrome Wolf-Hirschhorn (4p-) Syndrome Feeding Difficulties:Feeding Difficulties:
• Central hypotonia poor suck
• Oral facial clefts difficulty in sucking
• Poorly coordinated swallow aspirations
• G.E. reflux irritability; recurrent RTI
• G.I. malformations – rare
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) SyndromeFeeding Difficulties:Feeding Difficulties:
Health Supervision
• Sustain weight gain and health status improvement of motor abilities
• Protect the airway
• Cope with G.E. reflux
• Referral to a dysphagia team - Swallowing studies in infancy + gastrostomy tube
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
Feeding DifficultiesFeeding Difficulties
Treatment
• Increased caloric formulas and/or oral/nasogastric tube feeding
• Standard therapy for G.E. reflux - Nissen-Hill fundoplication
• Gastrostomy 40%
Wolf-Hirschhorn (4p-) Syndrome Wolf-Hirschhorn (4p-) Syndrome SeizuresSeizures
• Occurs in 90%
• Distinctive EEG abnormalities
Seizures In WHSSeizures In WHS• Onset between 3 to 23 months of age, with a
peak incidence at around 9 to 10 months
• Unilateral clonic/tonic, with or without secondary generalization
• Generalized tonic clonic
• On occasions lasting more than 15 minutes
• Often in clusters
Seizures In WHSSeizures In WHS
• Unilateral/generalized, clonic or tonic-clonic
status epilepticus: 60%
• Atypical absences (with a mild myoclonic component), by 1 to 5 years of age: 60%
• Seizures stopped, by 2 to 13 years of age: 33%
• Off medication: 16%
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) SyndromeSeizures/EpilepsySeizures/Epilepsy
• A candidate gene for epilepsy was the GABAA
receptor gene. Maps proximal to the WHSCR (4p12-p13).
• LETM1, a gene probably involved in Ca signaling, flanking the WHSCR (and falling within the newly proposed WHSCR-2), seems to be a good candidate for seizures.
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Seizures/EpilepsySeizures/Epilepsy
Treatment• Clonic/tonic-clonic seizures valproate or phenobarbital
• Atypical absences valproate ethosuccimide benzodiazepines (carbamazepine worsens)
• Clonic/tonic-clonic or absence/myoclonic status epilepticus iv. Benzodiazepines
- Dr. Battaglia
Wolf-Hirschhorn (4p-) Syndrome Wolf-Hirschhorn (4p-) Syndrome Developmental DisabilitiesDevelopmental Disabilities
• Recent studies of large samples of individuals recognition of a more complete continuum of the phenotype, pointing out a much wider clinical spectrum than previously thought (Battaglia & Carey, 2000; Battaglia et al., 2001, 2002)
Wolf-Hirschhorn(4p-) SyndromeWolf-Hirschhorn(4p-) SyndromeDevelopmental DisabilitiesDevelopmental Disabilities
Significant 65%
Moderate 25%
Mild 10%
Wolf-Hirschhorn (4P-) SyndromeWolf-Hirschhorn (4P-) SyndromeDevelopmental DisabilitiesDevelopmental Disabilities
Findings
Expressive Language:
Sounds / Words
Simple Sentences (6%)
Wolf-Hirschhorn (4P-) SyndromeWolf-Hirschhorn (4P-) SyndromeDevelopmental DisabilitiesDevelopmental Disabilities
Findings
Comprehension: Limited/Contextual
Intention to communicate: Poor/Absent in early years
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Developmental DisabilitiesDevelopmental Disabilities
• Sphincter control:
• Walking unsupported:
• Walking with walker:
• Help dressing/undressing:
• Doing household tasks:
age 8-14 yr (day) 10%
age 2-7 yr 27%
age 2-12 yr 18%
age 8-14 yr 18%
age 8-14 yr 18%
Findings
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Developmental DisabilitiesDevelopmental Disabilities
Findings
Follow up (20 yr): • Improvement of the motor abilities and of the disorder
of affect
• Improved adaptation to new situations; initial differentiation of the “I” processes
• Improvement of the communicative abilities and of the verbal comprehension with extension of the gesture repertoire
• Reduction of isolation and anxiety
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Developmental DisabilitiesDevelopmental Disabilities
Health Supervision
• Absent/poor speech speech evaluation
• DD psychometric evaluation
• Impaired motoric aspects motoric evaluation
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Developmental DisabilitiesDevelopmental Disabilities
Health Supervision & Treatment
• Referral to early intervention programs.
• Enrollment in an individualized rehabilitation program that covers motor aspects (including oral motor and feeding therapy), cognition, communication, and socialization.
• Appropriate school placement after full evaluation
• Planning for transition to adulthood (vocational training, living situation) to begin in adolescence.
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
Other Clinical Findings
• Heart anomalies: Not complex; amenable to repair
• Genitourinary: Variety of structural defects (high degree of vesicoureteric reflux) – watch for
• Eye: Coloboma, glaucoma, ptosis
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
Other Clinical Findings
• Dental: Altered tooth development
• Skeletal: Medically significant malformations to minor anomalies of limbs and skeleton; scoliosis
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Health SupervisionHealth Supervision
• Heart auscultation/EKG/echocardiography in infancy
• Renal function/renal ultrasound testing in
infancy and later
• Ophthalmology consultation in infancy
• Otolaryngological evaluation and audiological screening mandatory in infancy/childhood
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) SyndromeHealth SupervisionHealth Supervision
• Orthodontic evaluation in children/adolescents
• Club feet: early referral for evaluation/treatment
• Scoliosis/kyphosis: routine check
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
The right and the need of each patient with WHS to receive not just the ordinary care given to any child but also the extraordinary care necessary for coping with the problems of the del(4p) disorder.
Battaglia A, Carey JC, Wright TJBattaglia A, Carey JC, Wright TJWolf-Hirschhorn SyndromeWolf-Hirschhorn Syndrome
(Updated June 2006)(Updated June 2006)
In: GeneReviews: Genetic Disease Online Reviews at
GeneTests-GeneClinics [database online].
Copyright, University of Washington, Seattle. Available at
http://www.geneclinics.org
Battaglia, A. Battaglia, A. Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
in
Management of Genetic Syndromes, 2nd Edition
Cassidy SB, Allanson JE (eds)
Wiley Publishers, New York, NY, 2004.
Wolf-Hirschhorn (4p-) Syndrome:Wolf-Hirschhorn (4p-) Syndrome: Molecular Genetic PathogenesisMolecular Genetic Pathogenesis
• Over the last 10 years the WHSCR (the minimal deleted region) has been reduced to 165 kb (Wright et al., 1997). It contains two important genes of unknown function, WHSC1 and WHSC2 (Wright et al., 1997; Stec et al., 1998).
• Several candidate genes, including FGFR3, MSX1, and LETM1, fall in the flanking regions. These genes are deleted in most patients and may play a role in some aspects of the phenotype.
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome Molecular Genetic PathogenesisMolecular Genetic Pathogenesis
• More recently, Endele et al., (2003) and Winterpacht et al., (2003) identified three novel genes (WHSC3, WHSC4, WHSC5) in the critical region
Wolf-Hirschhorn (4p-) SyndromeWolf-Hirschhorn (4p-) Syndrome
Molecular Genetic PathogenesisMolecular Genetic Pathogenesis• A new WHSCR-2, contiguous distally to the
currently defined critical region, has recently been proposed (Zollino et al., 2003)
• DFNA6, one of the>25 genes responsible for nshl has been mapped to 4p16.3snhd in 15% WHS
Genetics of WHSGenetics of WHSDeletions involving 4p16.3 due to different types of
rearrangements:• Unbalanced translocation either new or from a parental balanced
translocation (~15-25%)
possible parental chromosomes:balanced
affected offspring: both a deletion of some gray chromosome and a duplication of some red chromosome
these rearrangements may be too small to see cytogenetically (cryptic)
Previous karyotype
Previous FISH Current array CGH results
Comparison
415
46,XY Deleted for WHS probe;
Subtelomere FISH panel: 4p deleted and replaced with 7p
CGH microarray identified same abnormalities as FISH, but also gave approximate sizes of the deletion and the duplication
CGH microarray is superior in characterizing many cryptic abnormalities
4
4p deletion 3.5-4.5 Mb
7p duplication6-7 Mb
Additional ExamplesAdditional Examples
Cytogenetic Finding CGH Microarray Result
46,XX 4p deletion and 11p duplication
46,XX 4p deletion and 8p duplication
46,XX,del(4p) 4p deletion and 11p duplication
46,XX,inv(4p) 4p deletion and 8p duplication
Limitations of CGH microarrayLimitations of CGH microarray• Will only detect the gain or loss of genomic material
that is represented on the slide
• No slide is yet clinically available that represents the entire human genome (currently can still miss very small imbalances)
• Repetitive regions of the human genome are cannot be analyzed using this technology
Chromosome ends with repetitive Chromosome ends with repetitive DNA – the acrocentricsDNA – the acrocentrics
Both the stalk and the satellite region contain only repetitive DNA and are not represented on CGH microarray slides
Previous karyotype
Previous FISH
Chromosome 4 image
CGH microarray FISH with chromosome 15p probe
636
4p deleted and replaced with unknown material
Deleted for WHS critical region
Only detected a 4p deletion
15
15
15p probe in green
4
CGH micoarray does NOT identify unbalanced translocations involving acrocentric p-arms
der(4)
2 other patients in this group also had unbalanced translocations involving an acrocentric p-arm only detected using a combination of regular cytogenetic studies (microscope) and FISH with probes specific to the acrocentric p-arms
Patients with an unbalanced translocation often Patients with an unbalanced translocation often present with an exception to some expected clinical present with an exception to some expected clinical
manifestationsmanifestations
• Microcephaly– Previous reports: present in almost all patients
(Estabrooks et. al, 1995; Zollino et. al, 2000; Buggenhout et. al, 2004)
– 3/16 did not have microcephaly– all had a cryptic deletion of 4p and duplication of 11p
Patients with an unbalanced translocation often Patients with an unbalanced translocation often present with an exception to some expected clinical present with an exception to some expected clinical
manifestationsmanifestations
• Hypospadias– Previous report: greater than 4.4 Mb deletion (Zollino et. al, 2000)
– 7/9 males in our study had hypospadias– 4/7 less than 4.4 Mb deletion and all had unbalanced
translocations• 4p deletion; 15p duplication
• 4p deletion; 14p or 22p duplication
• 4p deletion; 11p duplication (cryptic)
• 4p deletion; 7p duplication (cryptic)
• Hearing loss– Previous report: greater than ~6 Mb deletion (Estabrooks et. al,
1995)
– 9/25 patients in our study had hearing loss– 3/9 less than 6 Mb deletion
2/3 had unbalanced translocations• 4p deletion; 11p duplication (cryptic)
• 4p deletion; 7p duplication (cryptic)
Patients with an unbalanced translocation often Patients with an unbalanced translocation often present with an exception to some expected clinical present with an exception to some expected clinical
manifestationsmanifestations
• Heart Defects– Previous report: greater than ~6.0 Mb deletion (Zollino et. al, 2000)
– 10/25 patients in our study had heart defects– 3/10 less than 6.0 Mb deletion
2/3 unbalanced translocation• 4p deletion; 7p duplication (cryptic)
• 4p deletion; 8p duplication (cryptic)
Patients with an unbalanced translocation often Patients with an unbalanced translocation often present with an exception to some expected present with an exception to some expected
clinical manifestationsclinical manifestations
ConclusionsConclusions
• CGH microarray successfully detected a deletion of 4p in each patient previously diagnosed with a 4p deletion (26/26).
• In a subset of patients (5/26), CGH microarray also detected
an additional duplication of another region not detected by a microscopic chromosome analysis plus WHS critical FISH.
• Subtelomeric FISH analysis was also able to detect these additional duplications; however, CGH microarray analysis was also able to characterize the size of the regions of deletion and duplication.
ConclusionsConclusions• CGH microarray analysis does not identify duplications of the
acrocentric p-arms
• CGH microarray should be used in conjunction with a regular karyotype analysis for optimal characterization of the genetic imbalance.
• De novo inheritance (new mutation) should not be presumed. Parental studies using the technology necessary to confirm the deletion in the child should be pursued to determine recurrence risk. – If deletion is cytogenetically visible in child, and did not require a FISH
confirmation, traditional cytogenetic analysis is sufficient for parental studies.
– If FISH was required for diagnosis of the child, parents should be studied by FISH with WHS critical region probe to rule out a cryptic balanced translocation in either parent.
ConclusionsConclusions
• Unbalanced translocations were more common than previously expected (42.3% (11/26) vs 15-25% respectively).
• Patients with an unbalanced translocation often confound some of the expected clinical manifestations.
AcknowledgementsAcknowledgements
• Primary Children’s Medical Center Foundation
• Children’s Health Research Center
• Patients with WHS, their families, and caregivers
• 4p- Support Group
• University of Utah Cytogenetics Laboratory