Apparent Opitz BBBG syndrome with a partial duplication of 5p

A coalescence of two syndromes in a girl with terminal deletion and inverted duplication of chromosome 5

Background

Rearrangements involving chromosome 5p often result in two syndromes, Cri-du-chat (CdC) and Trisomy 5p, caused by a deletion and duplication, respectively. The 5p15.2 has been defined as a critical region for CdC syndrome; however, genotype-phenotype studies allowed isolation of particular characteristics such as speech delay, cat-like cry and mental retardation, caused by distinct deletions of 5p. A varied clinical outcome was also observed in patients with Trisomy 5p. Duplications of 5p10-5p13.1 manifest themselves in a more severe phenotype, while trisomy of regions distal to 5p13 mainly causes mild and indistinct features. Combinations of a terminal deletion and inverted duplication of 5p are infrequent in literature. Consequences of these chromosomal rearrangements differ, depending on size of deletion and duplication in particular cases, although authors mainly describe the deletion as the cause of the observed clinical picture.

Case presentation

Here we present a 5-month-old Slovenian girl, with de novo terminal deletion and inverted duplication of chromosome 5p. Our patient presents features of both CdC and Trisomy 5. The most prominent features observed in our patient are a cat-like cry and severe malformations of the right ear.

Conclusion

The cat-like cry, characteristic of CdC syndrome, is noted in our patient despite the fact that the deletion is not fully consistent with previously defined cat-like cry critical region in this syndrome. Features like dolichocephaly, macrocephaly and ear malformations, associated with duplication of the critical region of Trisomy 5p, are also present, although this region has not been rearranged in our case. Therefore, the true meaning of the described chromosomal rearrangements is discussed.

Inverted duplication with terminal deletion of 5p and no cat-like cry

We report on a 6-year-old boy referred for cytogenetics study. A few non-specific features were observed in the newborn: hypotonia, failure to thrive, seizures, pre-auricular skin tags. Cat-like cry was not identified. No remarkable facial dysmorphism, gastrointestinal, respiratory or cardiac abnormalities were identified. At age 4 years, speech and motor skill delays were apparent. Karyotyping and FISH analysis revealed a de novo rearranged chromosome 5p, with subtelomeric deletion of 5p and a duplication of the cri-du-chat critical region. Array CGH using sub-megabase resolution tiling-set (SMRT) array followed by FISH analysis with labeled BACs showed a deletion of 5pter to 5p15.31 (0-6.9 Mb) and an inverted duplication of the greater part of 5p15.31 to the distal end of 5p14.3 (6.9-19.9 Mb). Although very rare, inverted duplications with terminal deletion (inv dup del) have been reported at different chromosomal ends. Our finding adds a second patient of inv dup del 5p to this growing list, and the potential causative mechanisms for this rearrangement are discussed. Review of the mapping information of cri-du-chat patients and the comparison with a previously reported patient suggested that the critical region for cat-like cry is located within a 0.6 Mb region.

The MID1/PP2A complex: a key to the pathogenesis of Opitz BBB/G syndrome

Opitz BBB/G syndrome is a monogenic disorder that is characterized by malformations of the ventral midline. Investigations into the underlying genetic defects and the pathobiochemistry of this syndrome have already shed light on the mechanisms of both the physiological and the pathological development of the ventral midline, a complicated multistep process. Moreover, these studies have revealed the ubiquitin-dependent regulation of microtubule-associated phosphatase 2A, a central mechanism in many cellular processes. In this review, we summarize recent findings and speculate upon their implications for both medical and general research.

De novo complete trisomy 5p: clinical and neuroradiological findings

Partial or complete duplication of 5p is a rare chromosomal abnormality in which genotype-phenotype correlation studies are hampered by other commonly associated chromosomal abnormalities. We report on a new patient in whom a complete de novo trisomy 5p in all metaphases represented the only chromosomal aberration. The present case further contributes to delineate the typical clinical picture of the trisomy 5p syndrome. Long-term clinical follow-up demonstrated low levels of secretory immunoglobulin A (IgA) on several occasions and likely related to the patient's recurrent respiratory infections (RRIs), a main clinical feature of the trisomy 5p syndrome. An extensive neuroradiological study detected a progressive triventricular hydrocephalus during the fist year of life with subsequent stabilization. Neuronal migration disorders were also present and probably account for the drug-resistant epilepsy presented by the patient.

Identification of a dup(5)(p15.3) by multicolor banding

A 7-year-old female was referred to the Genetics Clinic because of developmental delay and attentional difficulty. The patient was adopted and there was a nonspecific prenatal history of drug and alcohol abuse. The patient had clinical signs that were not compatible with typical fetal alcohol syndrome (FAS), although there was a history of alcohol exposure in utero, neurodevelopmental difficulties with learning and behavioral problems, and mild dysmorphisms. Cytogenetic analysis revealed an unbalanced female karyotype with a dup(5) containing additional chromosome 5 material at band 5p15.3. The dup(5) showed normal copy number of the cri-du-chat region on 5p15.2 using locus-specific probes D5S721 and D5S23. Multicolor banding of chromosome 5 (MetaSystems) using partial chromosome paint (pcp) probes showed a duplication of band 5p15.3. The karyotype of the patient was therefore interpreted as follows: 46,XX,add(5)mat.ish dup(5)(p15.3)(wcp5 +, D5S271 +, D5S23 +, C84C11/T3 + +, pcp5p15.3 + +). The patient's biological mother and maternal half-brother were found to carry the identical chromosome duplication. The clinical phenotype of the biological mother is complicated by a difficult lifestyle but there were apparent learning and behavioral difficulties at school. The half-brother is nondysmorphic and presents with learning problems and attention deficit disorder (ADD). His physical examination was normal. To the best of our knowledge, this is the first report of a limited duplication of 5p15.3. The clinical significance of the dup(5)(p15.3) is still uncertain but may be the basis for learning and attention difficulties.

Tertiary trisomy due to a reciprocal translocation of chromosomes 5 and 21 in a four-generation family

Tertiary trisomy, or double trisomy, is a rare occurrence. We present two individuals with a previously unreported tertiary trisomy for chromosomes 5p and 21q in an eight-generation pedigree. Their phenotypes are compared with other partial trisomies of either 5p or 21q from the literature. The propositus was diagnosed with trisomy 21 at 2 years of age after a karyotype study for short stature and developmental delay. His phenotype was described as atypical for Down syndrome. He presented at 9 years of age because of pervasive behavioral problems and obesity. He was brachycephalic with a flattened nasal bridge, but he lacked other characteristics of trisomy 21. Because of lack of phenotypic evidence of Down syndrome, a repeat karyotype was obtained and showed 47,XY, +der(21)t(5;21)(p15.1; q22.1), incorporating partial trisomies of both chromosomes 5 and 21. Mother had a balanced translocation, 46, XX,t(5;21)(p15.1; q22.1); 8 other relatives were examined. The translocation originated from the maternal great-grandmother, but only the propositus and his mentally retarded aunt had a similar phenotye and the derivative chromosome. Fluorescence in situ hybridization showed absence of band 21q22.2 in the derivative chromosome of the propositus and his aunt, indicating that neither had trisomy for the Down syndrome critical region. These cases represent a unique double partial trisomy of chromosome arms 5p and 21q that occurred because of 3:1 malsegregation of a reciprocal translocation. These cases further demonstrate that phenotypic discordance with cytogenetic results dictate further investigation using advanced cytogenetic hybridization.

Proximal partial 5p trisomy resulting from a maternal (19;5) insertion

We present a case with a partial duplication 5p11-->5p13.3 resulting from a maternal ins (19,5)(p11;p11-p13.3). The diagnosis was confirmed by FISH and complement component determinations. The clinical picture was similar to those described in patients with complete duplication of the short arm and in some patients with partial 5p duplications, affecting at least band 5p13. A special significance of band 5p13 in the clinical severity of 5p duplications is discussed.

Interstitial deletion 5p accompanied by dicentric ring formation of the deleted segment resulting in trisomy 5p13-cen

Karyotypes with an interstitial deletion and a marker chromosome formed from the deleted segment are rare. We identified such a rearrangement in a newborn infant, who presented with macrocephaly, asymmetric square skull, minor facial anomalies, omphalocele, inguinal hernias, hypospadias, and club feet. The karyotype 46,XY,del(5) (pter --> p13::cen --> qter)/47,XY,+dicr(5)(:p13 --> cen::p13 --> cen), del(5)(pter --> p13::cen --> qter) was identified by banding studies and FISH analysis in the peripheral lymphocytes. One breakpoint on the del(5) maps distal to GDNF, and FISH analysis using an alpha-satellite probe suggests that the proximal breakpoint maps within the centromere. The dicentric r(5) consists of two copies of the segment deleted in the del(5), resulting in trisomy of proximal 5p (5p13-cen). The phenotype of the propositus is compared with other trisomy 5p cases and possible mechanisms for the generation of this unique chromosomal rearrangement are discussed.

Congenital alacrima in a patient with G (Opitz Frias) syndrome

Congenital alacrima is an autosomal dominant disorder showing markedly deficient lacrimation and punctate corneal epithelial erosions. The G (Opitz-Frias) syndrome is also an autosomal dominant disorder characterised by hypertelorism, hypospadias, stridor, and dysphagia. Here we report a 5-year-old boy with the G syndrome presenting congenital alacrima.

Opitz GBBB syndrome: chromosomal evidence of an X-linked form

BBB syndrome and G syndrome were originally reported as distinct X-linked disorders. Clinical studies indicated that BBB and G syndromes were likely to represent variant expression of the same disorder, now referred to as "Opitz" GBBB syndrome. Several occurrences of male-to-male transmission in both syndromes led to the hypothesis that GBBB syndrome was a single autosomal dominant, sex influenced disorder, now tentatively mapped to 5p12-13. We report on a large pedigree in which GBBB syndrome appears to cosegregate with a pericentric inversion of the X chromosome inv(X)(p22.3q26). It indicates the possible existence of a true X-linked form of GBBB syndrome, which does not appear phenotypically different from its autosomal counterpart. The gene could map in the vicinity of the breakpoints, in Xp or Xq. The existence of two genes affecting a common pathogenetic pathway could explain the gender-dependent expressivity of GBBB phenotype.

Distal deletion of chromosome 13 in a child with the "opitz" GBBB syndrome

We describe a patient who had craniofacial and genitourinary abnormalities, swallowing difficulties, esophageal dysfunction, hypotonia and moderate developmental delay, and who also had a terminal deletion of chromosome 13 (q32.3qter). This MCA pattern strongly suggests the Opitz GBBB syndrome. The deletion of chromosome 13 was interpreted as terminal with a breakpoint at 12q32.3. Coagulation factors VII and X located in 13q34, were markedly reduced in the propositus. Although there is some clinical overlap between patients with terminal deletion of 13q and those with the Opitz GBBB syndrome, our patient manifests a whole pattern of abnormalities characteristics of the latter disorder. The concurrence of the Opitz GBBB syndrome and the chromosome abnormality in our patient could be due to chance or, be because a gene for the Opitz GBBB syndrome is located at the tip of 13q.

Opitz BBBG syndrome: new family with late-onset, serious complication

The Opitz BBBG syndrome is characterized by hypertelorism and (in male patients) hypospadias, in addition to a number of midline abnormalities: posterior laryngeal cleft, stridor, swallowing dysfunction, cardiac defects, imperforate anus, and urinary tract and CNS anomalies. Inheritance is autosomal dominant (McKusick number *145410) with partial male sex limitation in most pedigrees. We report a Dutch family with Opitz BBBG syndrome in which the proband developed late-onset symptoms of a structural laryngeal abnormality.

De novo dup (5p) in a patient with congenital hypoplasia of the adrenal gland

We report on a black male child with congenital hypoplasia of the adrenal gland (CHA) with a de novo duplication of 5p [dir dup(5) (p13.3-->p15.1)], confirmed by fluorescence in situ hybridization (FISH). In addition to a characteristic clinical course, the patient has hyperpigmentation (melanoderma) since birth, normal external genitalia, marked elevation of ACTH, and absent response to an IV ACTH challenge. To the best of our knowledge, this is the first case of congenital hypoplasia of the adrenal gland associated with a chromosome abnormality. Reviews of dup (5p) and of our patient suggest that duplication of 5p13.3-pter has only minor phenotypic effect, while duplication of the relatively small critical segment p11-p13.2 apparently causes far more deleterious changes. The concurrence of CHA and dup(5p) in our patient may indicate the possible gene localization of an autosomal form of CHA to either at or near 5p13.3 or 5p15.1.

Opitz (BBB/G) syndrome: oral manifestations

We studied a new case of the G (Opitz BBB/G) syndrome in a 12-year-old boy. Several relatives had partial manifestations of the disorder. A comprehensive dental evaluation of the propositus was conducted; included is, to our knowledge, the first published cephalometric analysis of a G syndrome patient. We reviewed 139 cases of the G syndrome; 48 of them had at least one oral abnormality. These included clefting, micrognathia, ankyloglossia, and high-arched palate. Male G syndrome patients are more likely to have oral anomalies than affected females.