A girl with del(4)(q33) and occipital encephalocele: clinical description and molecular genetic characterization of a rare patient

We present clinical and developmental data on a girl with a de novo terminal deletion of the long arm of chromosome 4, del(4)(q33). The patient was evaluated at birth and followed up until 5 years of age. She showed facial and digital dysmorphism, a complex congenital heart defect, a large occipital encephalocele, and postnatal growth deficiency. Her neuropsychomotor milestones were delayed, and she developed learning difficulties. Apart from standard Giemsa banding, a molecular genetic analysis was performed using a comparative genomic hybridization (CGH) array. This revealed a terminal deletion at the band 4q32.3, which is directly adjacent to 4q33. The clinical findings in our patient differ from those described previously in patients with del(4)(q33) and del(4)(q32), respectively. In particular, the prominent occipital encephalocele has not been observed before in a terminal 4q deletion.     

Molecular cytogenetic characterization of the first reported case of an inv dup (4p)(p15.1-pter) with a concomitant 4q35.1-qter deletion and normal parents

Inverted duplications associated with terminal deletions are complex anomalies described in an increasing of chromosome ends. We report on the cytogenetic characterization of the first de novo inv dup del(4) with partial 4p duplication and 4q deletion in a girl with clinical signs consistent with “recombinant 4 syndrome”. This abnormality was suspected by banding, but high-resolution molecular cytogenetic investigations allowed us to define the breakpoints of the rearrangement. The terminal duplicated region extending from 4p15.1 to the telomere was estimated to be 29.27 Mb, while the size of the terminal deletion was 3.114 Mb in the 4q35.1 region. Until now, 10 patients with duplicated 4p14-p15 and deleted 4q35 chromosome 4 have been described. In all cases the abnormal chromosome 4 was derived from a pericentric inversion inherited from one of the parents. In conclusion, we have identified the first case of inv dup del(4) with normal parents suggesting that, often, terminal duplications or terminal deletions mask complex rearrangements.     

Partial trisomy 7q and monosomy 13q in a child with disorder of sex development: Phenotypic and genotypic findings

Terminal 7q duplication and terminal 13q deletion are two conditions with variable phenotypes including microcephaly, thumb a-/hypoplasia, cortical dysplasia, microphtalmia, intellectual disability and dysmorphic features. We describe a boy born to a mother with a reciprocal t (7;13) who combines both a terminal 7q33-qter duplication and terminal 13q33-qter deletion through the inheritance of a derivative chromosome 13 (der (13)). The patient presented with developmental delay, facial and non-facial dysmorphic features, hypertonia, genital abnormality and skeletal malformation but no thumb a-/hypoplasia or microphtalmia. Knowing the exact breakpoints of his chromosomal aberrations using high resolution array CGH (aCGH) and comparison of his phenotypes with those of 24 and 59 previously published cases of 7q duplication and 13q deletion, respectively, allow us to further narrow the size of the proposed critical regions for microcephaly, thumb a-/hypoplasia and hypo/hypertonia on chromosome 13.     

The 4q-Syndrome

The 4q-Syndrome: Here we report four cases of interstitial and terminal deletions of the long arm of chromosome 4. Case 1 is a 16 month old boy with del(4)(q12q21) who has soft dysmorphic features, tetralogy of Fallot, and severe developmental delay. Case 2 is a male infant with the same deletion and congenital cardiomyopathy. He suffered severe birth asphyxia and died at the age of 6 months. His father was found to have a complex chromosome 4 rearrangement. Case 3 is a female infant with del(4)(q33) who died of aspiration pneumonia. She was mildly dysmorphic and presented with heart failure and hypercalcaemia. Case 4 is a 8 month old girl who has del(4)(q33) and Pierre-Robin sequence. So far about 70 patients with microscopically visible deletions of chromosome 4q have been described. Although they vary in their phenotypes, they have several features in common. We suggest to use the term 4q-syndrome for all macrodeletions of the long arm of chromosome 4.     

A de novo complex t(7;13;8) translocation with a deletion in the TRPS gene region

Molecular cytogenetic analyses have resolved the pathogenetic aberration of an 8-year-old girl with tricho-rhino-phalangeal syndrome type I (TRPS I), normal intelligence, and a karyotype originally described as 46,XX,t(8;13)(q24;q21). R- and Q-banding and high resolution R-banding analyses have also disclosed a seemingly mosaic abnormality of the distal short arm of chromosome 7 but have not fully characterized this abnormality. Combined primed in situ labelling and chromosome painting, and three-colour chromosome painting have revealed a complex, apparently balanced translocation t(7;13;8). Fluorescence in situ hybridization with yeast artificial chromosome and cosmid clones from 8q24.1 has shown an interstitial deletion of at least 3 Mb covering most of the TRPS I critical region. Received: 27 December 1996 / Accepted: 27 March 1997     

Molecular characterization of a 130-kb terminal microdeletion at 22q in a child with mild mental retardation.

We have analyzed a recently described 22q13.3 microdeletion in a child with some overlapping features of the cytologically visible 22q13.3 deletion syndrome. Patient NT, who shows mild mental retardation and delay of expressive speech, was previously found to have a paternal microdeletion in the subtelomeric region of 22q. In order to characterize this abnormality further, we have constructed a cosmid/P1 contig covering the terminal 150 kb of 22q, which encompasses the 130-kb microdeletion. The microdeletion breakpoint is within the VNTR locus D22S163. The cloning of the breakpoint sequence revealed that the broken chromosome end was healed by the addition of telomeric repeats, indicating that the microdeletion is terminal. This is the first cloned terminal deletion breakpoint on a human chromosome other than 16p. The cosmid/P1 contig was mapped by pulsed-field gel electrophoresis analysis to within 120 kb of the arylsulfatase A gene, which places the contig in relation to genetic and physical maps of the chromosome. The acrosin gene maps within the microdeletion, approximately 70 kb from the telomere. With the distal end of chromosome 22q cloned, it is now possible to isolate genes that may be involved in the overlapping phenotype of this microdeletion and 22q13.3 deletion syndrome.     

Phenotypical characterization of 13q deletion syndrome: Report of two cases

Patients with 13q deletion syndrome are characterized with different phenotypical features depending on the size and location of the deleted region on chromosome 13. These patients fall into three groups: In Group 1, deleted region is in the proximal and does not extend into q32; in Group 2, deleted region involves proximal to the q32 and in Group 3 q33-q34 is deleted. We present two cases with 13q syndrome with two different deleted region and different severity on clinical features: One case with interstitial deletion belongs to the Group 1 with mild mental retardation and minor malformations and the other case with terminal deletion belongs to Group 3 with moderate to severe mental retardation and major malformations.     

Interstitial deletion of chromosome 6q: Precise definition of the breakpoints by microdissection,DNA amplification,and reverse painting

Routine chromosomal analysis using GTG-banding alone showed a mosaic terminal deletion of 6q in a 14-week-old boy with developmental retardation, facial anomalies, agenesis of corpus callosum, cleft palate, hypotonia, short neck and pterygium colli, and minor anomalies of hands and feet. Discrepancies between the clinical findings on our patient and those described in the literature on patients having terminal deletions led to a more precise analysis of the karyotype. Reverse painting was performed on normal G-banded metaphases for exact determination of the breakpoints and on metaphases of the patient for evaluation of mosaicism. A DNA library that was obtained by microdissection of three deleted chromosomes 6 was used as a painting probe. Subsequent DNA amplification was performed with the help of topoisomerase-pretreated degenerate oligonucleotide primers. Unexpectedly, the hybridization pattern on normal metaphase chromosomes revealed an interstitial deletion with breakpoints at 6q25.1 and 6q27 instead of a terminal deletion. Hybridization on metaphases of the patient showed one deleted chromosome 6 in all metaphases analyzed at a higher resolution rather than mosaicism as previously assumed [karyotype, 46,XY,del(6)(q25.1→q27)]. We assume that in the single cases of 6q^– described in the literature the deletions are misclassified. This might be due to difficulties in distinguishing between interstitial and terminal deletions at 6q and in precisely defining chromosomal breakpoints after GTG-banding alone. Received: 29 November 1995 / Revised: 15 January 1996     

Molecular genetic study of the frequency of monosomy 22q11 in DiGeorge syndrome

It is well established that DiGeorge syndrome (DGS) may be associated with monosomy of 22q11-pter. More recently, DNA probes have been used to detect hemizygosity for this region in patients with no visible karyotypic abnormality. However, DGS has also been described in cases where the cytogenetic abnormality does not involve 22q11; for instance, four cases of 10p- have been reported. In this study we have prospectively analyzed patients, by using DNA markers from 22q11, to assess the frequency of 22q11 rearrangements in DGS. Twenty-one of 22 cases had demonstrable hemizygosity for 22q11. Cytogenetic analysis had identified interstitial deletion in 6 of 16 cases tested; in 6 other cases no karyotype was available. When these results are combined with those from our previous studies, 33 of 35 DGS patients had chromosome 22q11 deletions detectable by DNA probes.     

FISH-mapping of a 100-kb terminal 22q13 deletion

Both cytogenetically visible and cryptic deletions of the terminal region of chromosome 22q are associated with a clinical phenotype including mental retardation, delay in expressive speech development, hypotonia, normal to accelerated growth and minor facial dysmorphic features. The genes responsible for the development of the phenotype have not yet been identified, but a distal localization is probable, since the cytogenetically visible and the cryptic deletions show a similar pattern of symptoms. We report a 33-year-old woman with a submicroscopic 22q13 deletion, mild mental retardation, speech delay, autistic symptoms and mild facial dysmorphic features. The deletion was mapped by FISH using cosmid probes from terminal 22q13, and the size of the deletion was estimated to be 100 kb. Three genes are affected by the deletion in this patient. ACR and RABL2B are deleted and proSAP2 is disrupted. This observation, together with recently published data, supports the notion that proSAP2 is the most important contributor to the 22q13 deletion phenotype.     

Wolf Hirshhorn syndrome in a case of ring chromosome 4: phenotype and molecular cytogenetic findings

Ring chromosome 4 associates concomitant loss of the telomeric 4p and 4q regions and leads to variable clinical manifestations depending on the size of the deleted chromosomal material. We report on a patient with ring chromosome 4, showing the Wolf-Hirshhorn Syndrome (WHS) phenotype and minor symptoms of distal 4q deletion syndrome; the severity of the signs of WHS masks the symptomatology of the 4q deletion syndrome. The absence of seizures despite the absence of the specific 4p16.3 region with haploinsufficiency of the LETM1 gene is striking. The double telomeric deletion due to the ring chromosome formation confirmed by FISH has been rarely described in WHS.     

Post-zygotic breakage of a dicentric chromosome results in mosaicism for a telocentric 9p marker chromosome in a boy with developmental delay

Chromosomal rearrangements resulting in an inverted duplication and a terminal deletion (inv dup del) can occur due to three known mechanisms, two of them resulting in a normal copy region between the duplicated regions. These mechanisms involve the formation of a dicentric chromosome, which undergo breakage during cell division resulting in cells with either an inverted duplication and deletion or a terminal deletion. We describe a mosaic 3 year old patient with two cell lines carrying a chromosome 9p deletion where one of the cell lines contains an additional telocentric marker chromosome. Our patient is mosaic for the product of a double breakage of a dicentric chromosome including a centric fission. Mosaicism involving different rearrangements of the same chromosome is rare and suggests an early mitotic breakage event.     

Partial monosomy of long arm of chromosome 4 due to interstitial deletion

Summary A child with congenital malformations and a de novo interstitial deletion of the long arm of chromosome 4 is described. Detailed analysis by G banding revealed the loss of the whole of band q21 and part of bands q13 and q22. The clinical abnormalities are quite dissimilar from those features described in other cases of partial 4q monosomy, which generally appear to result from the deletion of more distally placed segments of the chromosome.     

Chromosome deletion at 11q23 in an abnormal child from a family with inherited fragility at 11q23

Summary A neonate with clinical features of the 11q23 deletion syndrome was apparently mosaic with the dominant cell line showing deletion of the chromosomal segment 11q23.3 to 11qter. The presence of a few lymphocytes with a normal karyotype indicates post-zygotic deletion of chromosome 11. The mother and brother of the propositus show folate-sensitive fragility at band 11q23.3. This case indicates in vivo deletion at a folate-sensitive fragile site.     

Two cases of terminal deletion of chromosome 13: clinical features, conventional and molecular cytogenetic analysis

We report the cases of two unrelated patients with psychomotor retardation and craniofacial abnormalities, in whom cytogenetic studies have revealed a terminal deletion of chromosome 13 confirmed by fluorescence in situ hybridization (FISH). This del(13)(q33.2) is the smallest terminal deletion of the 13q reported so far. Interestingly enough, the serum level of coagulation factors VII and X, whose genes are located in 13q34, were reduced in both patients. These cases illustrate the difficulties in identifying precisely chromosome deletions and demonstrate that FISH techniques allow to obtain a more precise correlation between clinical phenotype and cytogenetic abnormalities.     

Ring chromosome 10: report on two patients and review of the literature

Ring chromosome 10—r(10)—is a rare disorder, with 14 cases reported in the literature, but only two with breakpoint determination by high-resolution techniques. We report here on two patients presenting a ring chromosome 10, studied by G-banding, fluorescent in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA) and SNP-array techniques, in order to investigate ring instability and determine breakpoints. Patient 1 showed a r(10)(p15.3q26.2) with a 7.9 Mb deletion in 10q26.2-q26.2, while patient 2 showed a r(10)(p15.3q26.13) with a 1.0 Mb deletion in 10p15.3 and a 8.8 Mb deletion in 10q26.13-q26.3, both unstable. While patient 1 presented with clinical features usually found in patients with r(10) and terminal 10q deletion, patient 2 presented characteristics so far not described in other patients with r(10), such as Dandy-Walker variant, osteopenia, semi-flexed legs, and dermal pigmentation regions. Our data and the data from literature show that there are no specific clinical findings to define a r(10) syndrome.     

Correlations between karyotype and phenotype in structural and numerical abnormalities of chromosome 18]

Five cases with different abnormalities of chromosome 18 are described: one case with trisomy 18, two cases with ring 18, one case with partial trisomy 18q and one case with a mosaic 18p-/iso 18q. The karyotypes of the parents were normal. Cytogenetic analysis was performed on PHA stimulated blood lymphocytes. GTG, QFQ, MTX banding techniques were used. Karyotype-phenotype correlations are made. All patients present mental retardation, hypotonia and facial dismorphisms. The different degree of mental retardation and the clinical signs are in relation to the different size of deletions or trisomies of the short or long arm of chromosome 18. In the case with mosaicism 18p-/iso18q the phenotype is determined from the chromosomal abnormality more frequent in the cells (18p-).     

Partial trisomy 4q and monosomy 9p resulting from a familial translocation t(4;9)(q27;p24) in a child with choanal atresia.

A male infant with a deletion of 9p and concomitant duplication of 4q: 46,XY, der(9)t(4;9)(q27;p24), is described. Parental chromosome analysis showed a balanced maternal translocation. To our knowledge, the above cytogenetic and clinical abnormalities have not been described previously. A phenotype comparison is presented with previously reported cases concerning a deletion of 9p and a duplication of 4q.     

Deficiency,transposition, and duplication of one 15q region may be alternatively associated with Prader-Willi (or a similar) syndrome. Analysis of seven cases after varying ascertainment

Seven patients are described who have some or all of the symptoms of Prader-Willi syndrome. They were ascertained by varying criteria starting either from the clinical picture or from the identification of a chromosome abnormality involving the proximal portion of the long arm of chromosome 15. The chromosome abnormalities consisted of two balanced translocations (15;18 and 8;15), three unbalanced ones (15;18, 15;19, and 9;15), and one interstitial deletion of bands 15q11 and q12. The seventh case had an unidentified extra chromosome. These data and a review of the literature led to the conclusion that deficiency, transposition, and even duplication of the region(s) 15q11-q13 may all result in a syndrome which is identifiable with or similar to the Prader-Willi syndrome.     

Recombinant chromosome 14 due to maternal pericentric inversion

Chromosome 14 is often involved in various chromosome rearrangements, most of them balanced. Human chromosome 14 is acrocentric, so its pericentric inversions are extremely rare (only few cases have been described in the literature). Here we report on a boy with congenital malformations and recombinant chromosome 14 inherited from his mother carrying a pericentric inversion. The proband's G-banded chromosome analysis revealed derivative chromosome 14. Comparative genomic hybridization analysis identified duplication of the terminal part of chromosome 14q ish cgh dup(14)(q32.1qter). This abnormality has been confirmed by custom BAC FISH analysis. His mother's karyotype was 46,XX,inv(14)(p11.2q32.1).