Familial Wolf's syndrome with a hidden 4p deletion by translocation of an 8p segment. Unbalanced inheritance from a maternal translocation (4;8)(p15.3;p22). Case report, review and risk estimates

Clinical and epilepsy characteristics in Wolf-Hirschhorn syndrome (4p-): A review

Wolf-Hirschhorn syndrome (WHS) is araredisorderwithan estimated prevalence being around 1 in 50,000 births. The syndrome is caused by the deletion of a critical region (Wolf-Hirschhorn Syndrome Critical region- WHSCR) on chromosome 4p16.3. WHS is clinically characterized by pre-and postnatal growth restriction, hypotonia, intellectual disability, craniofacial dysmorphismand congenital fusion anomalies. The clinical aspects are variable due to the deletion size.Consistently, epilepsy is one of the major concerns for parents and professionals caring for children with WHS. Seizures tend to occur in over 90% of patients, with onset within the first 3 years of life, and a peak incidence at around 6-12 months of age. Approximately 20% of patients had the first seizure onset within the first 6 months of age, almost 50% at 6 to 12 months of age and about 25% later than 12 months of age. The main types of epileptic seizures occurring in patients with WHS were generalized tonic-clonic seizures (around 70%). These were followed by tonic spasms (20%); focal seizures with impaired awareness (12%) and clonicseizures in 7% of patients.Seizures are often triggered by fever, followed by infections of various systems. Particularly, half of WHS patients experience status epilepticus in the first years of life, which can be fatal. Due to limited number of reports on the topic of EEG abnormalities in epilepsy among WHS patients, it is difficult to determine whether there are any characteristic deviations for WHS. Although more than 300 persons with WHS have been reported in the literature, there is sparse knowledge about epilepsy and methods of its anti-seizure medication (ASM) management with an assessment of their effectiveness. The purpose of this systematic review is to briefly summarize achievements and advances in the field of epilepsy in Wolf-Hirschhorn syndrome.

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.

Impact of chromosome 4p- syndrome on communication and expressive language skills: a preliminary investigation

PURPOSE

The purpose of this investigation was to examine the impact of Chromosome 4p- syndrome on the communication and expressive language phenotype of a large cross-cultural population of children, adolescents, and adults.

METHOD

A large-scale survey study was conducted and a descriptive research design was used to analyze quantitative and qualitative data regarding the communication and expressive language manifestations of 200 children, youth, and adults from 16 countries and Puerto Rico who had been diagnosed with 4p conditions, including Wolf-Hirschhorn syndrome (WHS), Pitt-Rogers-Danks syndrome (PRDS), Proximal 4p Deletion syndrome, and complex chromosomal rearrangements associated with 4p-.

RESULTS

Individuals with Chromosome 4p- syndrome represent a heterogeneous population with complex phenotypic profiles. The majority of the participants exhibited communication and expressive language skills below the 36-month developmental functioning level. A relatively small cohort of the study population exhibited advanced expressive language skills, a finding not reported in the professional literature.

CONCLUSION

Results broaden the spectrum of expressive language skills associated with Chromosome 4p- syndrome and highlight the communication potential of a subset of individuals with 4p abnormalities for development of advanced language structures. It is hypothesized that the largest 4p deletion, which includes the 4p16.3 band and contiguous gene regions, results in the most severely affected expressive language phenotype.

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.

Seizure and EEG patterns in Wolf-Hirschhorn (4p-) syndrome

Wolf-Hirschhorn syndrome (WHS) is a well-characterized chromosomal disorder that occurs due to partial deletion of the short arm of chromosome 4 (4p-). Although, about 300 cases have been reported to date, limited data are available on electroclinical findings. Information given to parents at the time of diagnosis tends to be skewed to the extreme negative. To delineate the natural history of seizures and EEG patterns in WHS, and obtain better information on diagnosis or outcome in a clinical setting, we reviewed the available literature on electroclinical findings of WHS. 4p- syndrome is characterized by distinctive seizure and EEG patterns that facilitate the early diagnosis and management of such patients.

Ophthalmic manifestations of Wolf-Hirschhorn syndrome

PURPOSE

Wolf-Hirschhorn syndrome is caused by partial deletion of the short arm of chromosome 4 (4p-). Common features include developmental delay, microcephaly, seizures, craniofacial anomalies, mental retardation, and cardiac defects. This article further describes the ocular manifestations of this rare disorder.

METHODS

Charts of patients with 4p- from the University of Arkansas (n = 3) and the University of Minnesota (n = 7) were reviewed. Diagnosis was made by a geneticist and was confirmed by karyotype. Cytogenetic reports were available for review in eight patients.

RESULTS

Ten patients (six females and four males) aged 4 months to 11 years were included. Ophthalmic findings included exodeviation (9/10), nasolacrimal obstruction (6/10), shallow orbits (3/10), epicanthal folds (3/10), foveal hypoplasia (3/10), upper lid coloboma (2/10), optic disk anomalies (2/10), downslanting palpebral fissures (2/10), microcornea (2/10), hypertelorism (1/10), nystagmus (1/10), and chorioretinal coloboma (1/10). Eight patients with 4p- had break points ranging from band 4p14 to 4p16.3.

CONCLUSIONS

This study expands on previous reports of the ophthalmic phenotype in 4p- and includes the additional findings of foveal hypoplasia, nystagmus, shallow orbits, epicanthal folds, and upper lid colobomas. Ophthalmic findings in 4p- are variable, likely related to the size of the deletion.

A study of EEG and epilepsy profile in Wolf-Hirschhorn syndrome and considerations regarding its correlation with other chromosomal disorders

Wolf-Hirschhorn syndrome (WHS) is a genetic disorder caused by a deletion of the short arm of chromosome 4. Sgrò et al. described an electroclinical profile for WHS, but data regarding this issue are scarce. We report an 8-year-old girl presenting the classic phenotype for WHS, confirmed by FISH test. Epilepsy started during infancy with myoclonic seizures. Later, she presented atypical absences, which gradually increased in frequency, and at the age of 2.5 years, she presented a non-convulsive status epilepticus. Epilepsy was controlled with valproate at the age of 6 years. Serial EEGs were performed and showed unusual bursts of generalized, high amplitude delta waves with superimposed low-moderate amplitude sharp waves. A literature review was performed and our case was compared to others, where EEG and/or epilepsy were addressed. Our case and previously published data show that WHS presents a stereotyped epilepsy profile and EEG patterns. A discussion concerning similarities between these findings and those observed in Angelman syndrome has been performed, since in both syndromes, GABA genes are involved and may play a role in the pathogenesis. Although fascinating, this theory is simplistic, since patients with Angelman syndrome without GABA deletion may present epilepsy and EEG abnormalities. Another issue is the striking overlap regarding these features, between WHS and Pitt-Rogers-Danks syndrome, which may be a key in showing that these disorders could be a spectral variation of the same entity.

Chromosomal abnormalities and epilepsy: a review for clinicians and gene hunters

PURPOSE

We analyzed databases on chromosomal anomalies and epilepsy to identify chromosomal regions where abnormalities are associated with clinically recognizable epilepsy syndromes. The expectation was that these regions could then be offered as targets in the search for epilepsy genes.

METHODS

The cytogenetic program of the Oxford Medical Database, and the PubMed database were used to identify chromosomal aberrations associated with seizures and/or EEG abnormalities. The literature on selected small anomalies thus identified was reviewed from a clinical and electroencephalographic viewpoint, to classify the seizures and syndromes according to the current International League Against Epilepsy (ILAE) classification.

RESULTS

There were 400 different chromosomal imbalances described with seizures or EEG abnormalities. Eight chromosomal disorders had a high association with epilepsy. These comprised: the Wolf-Hirschhorn (4p-) syndrome, Miller-Dieker syndrome (del 17p13.3), Angelman syndrome (del 15q11-q13), the inversion duplication 15 syndrome, terminal deletions of chromosome 1q and 1p, and ring chromosomes 14 and 20. Many other segments had a weaker association with seizures. The poor quality of description of the epileptology in many reports thwarted an attempt to make precise karyotype-phenotype correlations.

CONCLUSIONS

We identified certain chromosomal regions where aberrations had an evident association with seizures, and these regions may be useful targets for gene hunters. New correlations with specific epilepsy syndromes were not revealed. Clinicians should continue to search for small chromosomal abnormalities associated with specific epilepsy syndromes that could provide important clues for finding epilepsy genes, and the epileptology should be rigorously characterized.

Wolf-Hirschorn syndrome resulting from partial monosomy 4p/trisomy 9p

An infant girl was referred for a genetic consultation because of facial appearance suggestive of Wolf-Hirschorn syndrome (WHS), growth retardation and generalized hypotonia. She had an unbalanced karyotype 46,XX,der(4)t(4;9)(p15.2;p22)mat resulting in the deletion of the critical region for WHS and duplication of the critical region for the 9p duplication syndrome. The mother and the grandmother of proposita were the carriers of an apparently balanced translocation 46,XX,t(4;9)(p15.2;p22). The infant's phenotype was characteristic of WHS syndrome rather than that of duplication 9p phenotype. This is probably the first description of WHS phenotype resulting from a familial 4;9 translocation.

Health supervision and anticipatory guidance of individuals with Wolf-Hirschhorn syndrome

Wolf-Hirschhorn syndrome (WHS) is a well-known malformation syndrome due to microdeletion of the short arm of chromosome 4 (4p-). Almost 120 cases have been reported so far, yet there is still limited information on its natural history. It is generally thought that these children have severe developmental disabilities and tend to be mere survivors devoid of personality. It is evident to us [Battaglia et al., 1999a, 1999b], however, that individuals with WHS are capable of greater psychomotor development than previously suggested [Guthrie et al., 1971]. Thus, it is even more important to establish guidelines for health supervision and anticipatory guidance of such patients. This would help professionals and families in developing the most appropriate individualized plan for each child, in order to allow the maximum achievement possible. In the present article we propose guidelines for health supervision and anticipatory guidance of individuals with WHS. These guidelines derive from our experience with the natural history of several children, adolescents, and adults with WHS, gained through the literature, personal observation, and contacts with the national support groups in North America and Italy.

Natural history of Wolf-Hirschhorn syndrome: experience with 15 cases

Wolf-Hirschhorn syndrome (WHS) is a well-known chromosomal disorder attributable to partial deletion of the short arm of chromosome 4 (4p-). Although about 120 cases have been reported so far, there is still very little data on its natural history. Information given to parents at the time of diagnosis tends to be skewed to the extreme negative. To help delineate more thoroughly the natural history of WHS, and to obtain better information to answer parents' questions in a clinical setting, we evaluated 15 patients (12 females, 3 males) in three centers with the 4p- syndrome. Four of the cases had a follow-up spanning 16 years. Thirteen cases were detected by standard cytogenetics (regular G-banding 10, high-resolution banding 3), while the remaining 2 required fluorescence in situ hybridization. A total of 5/15 (33.3%) had heart lesions; 7/15 (46. 6%) had oral facial clefts; 13/15 (86.6%) had a seizure disorder, that tended to disappear with age; and 100% had severe/profound developmental retardation. One Italian patient had sensorineural deafness and 1 Utah patient had a right split hand defect. Of note, 2 Utah patients were able to walk with support (at 4 and 12 years of age, respectively), whereas 3 Italian patients and 1 Utah patient were able to walk unassisted (at 4, 5, 5 years 9 months, and 7 years of age, respectively). Two of the 3 Italian patients also achieved sphincter control (by day). The 8 patients receiving serial electroencephalogram studies showed fairly distinctive abnormalities, usually outlasting seizures. A slow, but constant progress in development was observed in all cases, during the follow-up period. In conclusion, the combined cases of the three centers represent considerable experience, providing new information on several aspects of this important deletion syndrome.

Congenital scoliosis (hemivertebra) associated with de novo balanced reciprocal translocation, 46,XX,t(13;17)(q34;p11.2)

We report on an 8-year-old girl with congenital scoliosis (segmented hemivertebra between the second and third lumbar vertebrae) and psychomotor developmental delay. She has a de novo reciprocal translocation, t(13;17)(q34;p11.2). Congenital scoliosis is one type of structural spine deformation and hemivertebra is the most common anomaly causing congenital scoliosis. The cause and the mode of inheritance of hemivertebrae are unknown. Our patient has a de novo balanced chromosome aberration and retains two copies of the LLGL gene, which is usually lacking in patients with Smith-Magenis syndrome (SMS). Since some SMS patients who showed a deletion at 17p11.2 had congenital scoliosis, it is likely that one (17p11.2) of the breakpoints in our patient is a candidate region for a hemivertebra locus.

Translocations involving 4p16.3 in three families: deletion causing the Pitt-Rogers-Danks syndrome and duplication resulting in a new overgrowth syndrome

Three families are reported who have a translocation involving 4p16.3. Nine subjects are described with the clinical features of the Pitt-Rogers-Danks (PRD) syndrome confirming pre- and postnatal growth failure, microcephaly, severe mental retardation, seizures, and a distinctive facial appearance; a deletion of 4p16.3 was seen in all eight patients studied with fluorescence in situ hybridisation (FISH). Eleven subjects had a new syndrome with physical overgrowth, heavy facial features, and mild to moderate mental handicap; a duplication of the chromosome region 4p16.3 was found in the four subjects studied. It is suggested that the growth abnormalities in these two families may be explained by a dosage effect of the fibroblast growth factor receptor gene 3 (FGFR3), which is located at 4p16.3, that is, a single dose leads to growth failure and a triple dose to physical overgrowth. We describe the molecular mapping of the translocation breakpoint and define it to within locus D4S43.

Microdissection and DOP-PCR-based reverse chromosome painting as a fast and reliable strategy in the analysis of various structural chromosome abnormalities

Reverse chromosome painting has become a powerful tool in clinical genetics for the characterization of cytogenetically unclassifiable aberrations. In this report, the application of a sensitive and rapid procedure for the complete and precise identification of four different de novo structural chromosome abnormalities is presented. These chromosome rearrangements include a marker derived from chromosome 3(cen-q11), an interstitial deletion of chromosome 13 [del(13)(q14q22)], an unbalanced translocation [46,XY, -4, +der(4)t(4;8)(p 15.2;p21.1)] leading to Wolf-Hirschhorn syndrome, and a partial inverted duplication in conjunction with a partial deletion of chromosome 5p [46,XX, -5, +der(5)(:p13-p15.1::p15.1-qter)] which is responsible for the manifestation of the cri-du-chat syndrome. The importance of a fast and reliable evaluation of complex chromosome aberrations in pre- and postnatal diagnosis with regard to comprehensive genetic counselling is emphasized.

4p(-) syndrome: a chromosomal disorder associated with a particular EEG pattern

We report an electroclinical and cytogenetic study of 4 patients with Wolf-Hirschhorn syndrome (WHS). In all cases, we observed a stereotyped EEG and clinical picture characterized by generalized or unilateral myoclonic seizures followed later by brief atypical absences. Electrographically, these were accompanied by a sequence of centroparietal or parietotemporal sharp waves; high-voltage wave with a superimposed spike becoming unusual spike-wave complexes, often elicited by eye closure; burst of diffuse spikes and waves; and frequent jerks. This electroclinical pattern is very similar to the one described in Angelman syndrome (AS) in which a defect in GABAA receptor function has been suggested. Moreover, the genes encoding the GABAA receptor subunit have been mapped to the p12-p13 bands of chromosome 4. Even though the deletion in these cases does not encompass the 4p12-p13 region, we suggest that the electroclinical picture common to WHS and AS might represent a characteristic type of epilepsy linked to a common genetic abnormality.

Familial translocation resulting in Wolf-Hirschhorn syndrome in two related unbalanced individuals: clinical evaluation of a 39-year-old man with Wolf-Hirschhorn syndrome

A chromosomal translocation between chromosomes 4 and 8 resulting in Wolf-Hirschhorn syndrome in 2 individuals has been traced through 4 generations of a family. Ascertainment of the family was through a newborn infant with evident Wolf-Hirschhorn syndrome who had an unbalanced chromosomal translocation [46,XY,-4,+der(4),t(4;8) (p15.32;p22)]. Discussion with the family documented a paternal great-uncle who also had a similar phenotype and profound mental retardation. Subsequently this individual was found to have the same unbalanced chromosome constitution as the propositus. The 39-year-old great-uncle is the oldest reported individual with the Wolf-Hirschhorn syndrome. The importance of chromosome evaluation of older individuals with mental retardation syndromes is emphasized.

Long-term survival in the Wolf-Hirschhorn (4p-) syndrome

The clinical features of Wolf-Hirschhorn syndrome are described in a 29-year-old woman who shows severe retardation of growth and development. It is important for health care professionals involved with families in which this condition is present to realize that long-term survival may occur.

Toward the complete genomic map and molecular pathology of human chromosome 4

The identification of disease genes via molecular DNA cloning has revolutionized human genetics and medicine. Both the candidate gene approach and positional cloning have been used successfully. The defects causing Huntington's disease, facioscapulohumeral muscular dystrophy, piebaldism, Hurler/Scheie syndrome, one form of autosomal recessive retinitis pigmentosa, and a second locus for autosomal dominant polycystic kidney disease have recently been localized to chromosome 4. In addition to the rapid progress in the cloning of the 203-megabase chromosome, the presence of more than 60 closely spaced microsatellites on this chromosome will undoubtedly lead to the localization of additional disease genes. In order to consider cloned genes as potential candidates for disorders assigned to chromosome 4, it is important to collect and order all genes with respect to their chromosomal localization. Analysis of cytogenetically visible interstitial and terminal deletions should also be helpful in defining new disease gene loci and in mapping novel genes. These data represent the status quo of the integrated molecular map for chromosome 4.

Trisomy 8 syndrome owing to isodicentric 8p chromosomes: regional assignment of a presumptive gene involved in corpus callosum development

Two patients with trisomy 8 syndrome owing to an isodicentric 8p;8p chromosome are described. Case 1 had a 46,XX/46,XX,-8,+idic(8)(p23) karyotype while case 2, a male, had the same abnormal karyotype without evidence of mosaicism. In situ hybridisation, performed in case 1, showed that the isochromosome was asymmetrical. Agenesis of the corpus callosum (ACC), which is a feature of trisomy 8 syndrome, was found in both patients. Although ACC is associated with aneuploidies for different chromosomes, a review of published reports indicates that, when associated with chromosome 8, this defect is the result of duplication of a gene located within 8p21-pter. Molecular analysis in one of our patients led us to exclude the distal 23 Mb of 8p from this ACC region.

A complex rearrangement associated with sex reversal and the Wolf-Hirschhorn syndrome: a cytogenetic and molecular study

We report a male infant referred with multiple congenital abnormalities consistent with the Wolf-Hirschhorn syndrome. Cytogenetic analysis showed a chromosome complement of 46,XX with a deletion of 4p15.2----4pter and its replacement by material of unknown origin. The patient was positive for a number of Yp probes including SRY, the testis determining factor, and in situ hybridisation localised the Yp material to the tip of the short arm of one X chromosome. Using pDP230, a probe for the pseudoautosomal region, and M27 beta, which recognises a locus in proximal Xp, the material translocated on to 4p was identified as originating from the short arm of the paternal X chromosome. The most reasonable explanation for this complex rearrangement is two separate exchange events involving both chromatids of Xp during paternal meiosis. An aberrant X-Y interchange gave rise to the sex reversal and an X;4 translocation resulted in additional, apparently active Xp material and a deletion of 4p which produced the Wolf-Hirschhorn phenotype.

Congenital cardiovascular malformations (CCVM) and structural chromosome abnormalities: a report of 9 cases and literature review

Nine cases of congenital cardiovascular malformations (CCVM) with associated unbalanced structural chromosomal abnormalities were ascertained in a population-based study of heart defects, constituting 0.4% of the 2,103 cases of CCVM in the Baltimore-Washington Infant Study (BWIS). This represents a four-fold increase over the general population rate. In an effort to determine possible phenotype/karyotype correlations, the literature was searched for cases with similar karyotypic abnormalities. This comparison of 223 literature cases of karyotypic abnormalities with nine similar cases ascertained by heart malformation has provided the opportunity to review cardiac defects reported in cases of structural abnormalities of chromosomes 1, 3, 7, 8, 9, 10, 11, 15, and 18. The most common cardiac malformation present in the chromosomal cases was ventricular septal defect (VSD) (39%); similarly VSD is the most common CCVM among children with heart defects, although it is the primary defect in only 20% of the BWIS cases. Among all heart defects in the BWIS, atrial septal defect (ASD) represents 5.5% of all cases, but in cases of 8p duplication, ASD is present in 41%. In addition, 40% of cases of 9p duplication had an ASD. Similarly, 35% of cases of 11q duplication had an ASD. While the suggestion of specific karyotype/phenotype association is premature, information on additional cases might clarify the possibility that genetic determinants related to septum formation may reside on chromosome 8, 9, and/or 11. The variety of chromosomal abnormalities in cases with ventricular septal defect indicates one type of genetic heterogeneity that may be involved in this very common heart defect.

Familial Wolf-Hirschhorn syndrome associated with Rieger anomaly of the eye

The authors report the case of a male infant who presented with growth retardation and multiple congenital anomalies including bilateral cleft lip and palate, large glabella and broad nasal bridge. Eye examination revealed Rieger anomaly, nasolacrimal duct obstruction and mild microphthalmia bilaterally. In addition, shawl scrotum, nail hypoplasia and linear skin hypoplasia of the lower extremities were noted. Two G-banded chromosome studies were normal; prophase analysis showed 4p monosomy and 10q trisomy derived from a paternal balanced translocation. The clinical recognition of Wolf-Hirschhorn syndrome in this child, despite the two normal chromosome studies, allowed for the recognition of the cytogenetic aberration and identification of other family members who carry the balanced translocation.

Wolf-Hirschhorn locus is distal to D4S10 on short arm of chromosome 4

We report a family in which Wolf-Hirschhorn syndrome in two children with partial monosomy of the short arm of chromosome 4 is the result of unbalanced segregation of a reciprocal 4;12 translocation in the mother. Studies with the DNA probe G8 show that the translocation breakpoint in this family is distal to the D4S10 locus. Previously reported cases of Wolf-Hirschhorn syndrome have involved the deletion of D4S10. These observations may prove helpful in the search for better genetic markers for Huntington's chorea, which maps close to D4S10.

Familial transmission of Wolf syndrome resulting from specific deletion 4p16 from t(4;8)(p16;p21) mat

Wolf syndrome has been recognized since the mid-sixties. It has also been postulated that the loss of 4p16 is the primary reason for the syndrome. However, in a handful of cases the breakpoints have been identified, only a very few of which are exclusively 4p16. In this report we present familial transmission of 4p16 deletion (associated with 8pter----8p21 duplication) in three individuals with typical expression of Wolf syndrome. The transmission occurs from a de novo balanced maternal translocation, 46,XX,t(4;8)(p16;p21). An effort has also been made to distinguish the terminal deletion syndrome from the emerging interstitial deletion syndrome of 4p.

Comments on methods and results in: Sherman et al., "Segregation analysis of balanced pericentric inversions in pedigree data"

The analysis by Sherman et al. (1986), its basis and results have been examined. The analysis relies on general methods, which may give acceptable results under the special conditions considered by the authors, but will usually produce more or less misleading results. The program POINTER (Lalouel & Morton 1981) is shown to be based partly on a chain of irrelevant arguments for the actual context. The so-called "conventional ascertainment rules" (Morton et al. 1983) are shown to produce misleading results in cases where their assumptions are not satisfied. The mean risk for unbalanced offspring is underestimated because of an erroneous ascertainment correction. The segregation frequencies are found to be different in three national samples, contrary to the claim by Sherman et al. Only a small proportion of all information available in the data has been utilized. Alternative and more appropriate models, hypotheses and procedures have been suggested. The frequent use of packages with computer programmes of standard statistical procedures in nonstandard situations with data from collaborative studies in human cytogenetics is discussed.

De novo del(4) (p15.32) with incomplete expression of the Wolf-Hirschhorn syndrome

A 7 7/12-year-old girl with a de novo deletion 4p15.32----pter without the typical Wolf-Hirschhorn syndrome (WHS) is presented. This observation and others from medical literature suggest that monosomy 4p15.31----4p15.32, rather than 4p16, is the cause of the typical WHS.

A taxonomic approach to the del(4p) phenotype

The findings of 23 patients with the del(4p) phenotype are compared systematically. Three patients with a small deletion evident only on analysis of extended chromosomes have a phenotype comparable to 13 patients with a more extensive chromosomal deletion. Two patients with no detectable deletion also fit into the phenotypic spectrum of patients with del(4p), suggesting the same etiology. Five patients with fewer typical and more atypical findings probably represent a heterogeneous group of other syndromes. Numerical analysis of the phenotype allows one to identify patients who most likely have a deletion requiring a more intensive cytogenetics analysis.

Wolf-Hirschhorn syndrome owing to 1:3 segregation of a maternal 4;21 translocation

We describe a child with Wolf-Hirschhorn syndrome with the karyotype 45,XY,inv(9)(p11q13)pat,-4,-21,+der(4),t(4;21)(p15.3;q11.2)mat. This is the second case known to us of Wolf-Hirschhorn syndrome caused by 1:3 segregation of a parental rearrangement. This mode of segregation can be predicted in both cases by a pachytene-diagram model. It is uncertain whether or not the proximal 21q monosomy in this case has affected the phenotype.