Hipoacusia en el síndrome de townes-brocks

In nineteen seventy two Towns and Brocks reported on a family in which the father and seven children showed anal atresia, triphalangeal thumb, metatarsal synostosis, extra fingers, neurosensorial deafness and ear abnormalities. The main traits were those related to hand, ear and anus alterations, transmitted under a dominant autosomal pattern. In this paper we present several members of the same family with similar alterations who finally were diagnosed of Townes-Brocks syndrome.

Pallister-Hall syndrome phenotype in mice mutant for Gli3

Mutations in the GLI3 gene have been identified in several human malformation syndromes. One of these autosomal dominant developmental disorders is Pallister-Hall syndrome (PHS; MIM146510), which is associated with central polydactyly and other malformations. Interestingly, the mutations in the GLI3 transcription factor gene identified in patients with PHS are restricted to the region 3' of the zinc finger-encoding domain, leaving this DNA-binding domain intact. We have investigated the consequences of this mutation on the development of multiple organ systems by introducing a targeted mutation in mice. We found that mice homozygous for the mutation showed a central polydactyly, thus modeling one of the major abnormalities of the human syndrome. Moreover, Gli3-mutant mice displayed a wide range of developmental abnormalities encompassing almost all of the common PHS features, including imperforate anus, gastrointestinal, epiglottis and larynx defects, abnormal kidney development, and absence of adrenal glands. Thus, our Gli3-mutant mice provide an excellent model for studies of both the pathogenesis of PHS and Gli3 functions in the development of the affected organ systems.

Pallister-Hall syndrome with stenosis of the cricoid cartilage and microphallus without hypopituitarism

The Pallister-Hall syndrome is characterised by a spectrum of anomalies including congenital hypothalamic "hamartoblastoma" hypopituitarism, imperforate anus, polydactyly and various visceral anomalies. Rare familial cases with an autosomal dominant inheritance pattern with variable expressivity have been reported. Cases of more mildly affected individuals with Pallister-Hall syndrome have been described, including cases of asymptomatic individuals. We report a case of Pallister-Hall syndrome with microphallus and without growth hormone deficiency that has been followed successfully for two years. The patient presented postaxial polydactyly of hands, dysplasic nails, imperforate anus, small penis, scrotum bifidum with very thin urethra, bifid epiglottis and a bilateral simian crease. There was vesico-ureteral-reflux, insertional hexadactyly of the left hand and two Y shaped metacarpal with six fingers at the right hand. Brain MR imaging revealed a large sellar and suprasellar mass. A perineal anorectoplasty and a vesicostomy were performed. Laryngeal dyspnea appeared when he was 13 months old. Bronchoscopy revealed anterior synechia of vocal cords with cricoidian stenosis. A tracheostomy was performed. Mental development was normal. No mutation of the zinc finger transcription factor gene, GLI 3 was detected.

Mapping loci causing susceptibility to anal atresia in pigs, using a resource pedigree

BACKGROUND/PURPOSE

Very little information on the genetic background for anal atresia (anorectal malformations; AA) in humans has been described. A strikingly similar natural anomaly occurs in piglets. The authors have used this as an animal model for various research purposes. The affected piglets were treated surgically soon after birth, raised, and used for breeding. The authors have generated a resource pedigree segregating for this naturally occurring nonsyndromal AA and describe here the first attempt to map susceptibility loci by marker analysis.

METHODS

A pig pedigree with a high incidence of AA has been established by selective breeding using 3 probands from the Landrace and Large White breeds. It has been maintained by intrafamilial crossing for more than 15 years. A backcross pedigree has now been generated by mating 4 AA females to an unaffected male from the Chinese Meishan breed. F(1) animals were both intercrossed and backcrossed to affected AA animals. A genome scan was carried out using the F(0), F(1), and affected backcross progeny. Ninety-two microsatellite loci were analyzed using fluorescently labelled primers and an ABI377 sequencer. Linkage analysis was done with the CRI-MAP 2.4 software.

RESULTS

Crossing affected parents increased the incidence of abnormalities from 30% to 61.9%. All 39 F(1) pigs were unaffected. In the F(1) intercross, only 3 of 205 (1.5%) were affected, whereas 42 of 523 (8.0%) backcross progeny were affected. The marked difference in the incidence of affected progeny in the F(1) intercross and in the backcross indicates the presence of multiple genes causing AA. The genome scan showed suggestive evidence for the presence of a susceptibility locus on pig chromosome 15 (lod score 2.7 for a pig microsatellite marker SW2072).

CONCLUSIONS

The results clearly show that AA has a oligogenic or polygenic background. The genome scan showed one suggestive locus causing AA on pig chromosome 15. The long-term goal is to identify causative genes for this malformation by comparative positional candidate cloning. This study provides, for the first time, linkage mapping of nonsyndromal anorectal malformations with a polygenic inheritance.

Townes-Brocks syndrome versus expanded spectrum hemifacial microsomia: review of eight patients and further evidence of a "hot spot" for mutation in the SALL1 gene

PURPOSE

It can be difficult to differentiate clinically between hemifacial microsomia (HFM) and Townes-Brocks syndrome (TBS). The distinction is important because TBS is inherited as an autosomal dominant trait, whereas HFM is sporadic.

METHODS

We performed a retrospective analysis of eight patients with HFM-expanded spectrum and anal anomalies to determine whether this subset has TBS.

RESULTS

Two patients had major phenotypic findings of TBS. Sequencing of SALL1, the gene mutated in TBS, in four of the eight patients revealed one with a C --> T transition (resulting in a nonsense mutation R276X) at a previously identified mutational "hot spot."

CONCLUSION

Patients with overlapping features of both syndromes should be screened for SALL1 mutations.

Usefulness and limitations of FISH to characterize partially cryptic complex chromosome rearrangements

Interpretation of a complex chromosome rearrangement (CCR) using only G-band analysis is difficult and potentially inaccurate. We present two patients with de novo, partially cryptic, CCRs that illustrate both the value and limitations of using fluorescence in situ hybridization (FISH) whole chromosome paint probes to characterize these types of rearrangements. In a patient referred because of features of Townes-Brocks syndrome, G-band analysis revealed an unbalanced CCR involving 3 chromosomes (2,11 and 16) and at least 4 breakpoints. A more complex rearrangement involving two cryptic insertions and at least 6 breakpoints, however, was detected using whole chromosome paint probes specific for the 3 chromosomes involved in the rearrangement. In this case, FISH studies were essential for accurate characterization of this patient's rearrangement. In a second patient, G-band analysis revealed that a 12-year-old male with obesity, small genitalia, attention deficit disorder, learning disabilities, and behavior problems, carried a CCR involving 4 chromosomes (3, 5, 10 and 13) with 6 breakpoints. This rearrangement seemed unbalanced, with missing terminal 3p26. 2-pter material. Our G-band interpretation of this karyotype was confirmed by FISH using whole chromosome paint probes specific for the involved chromosomes. Although no evidence of the "missing" 3pter material was observed using a chromosome 3 paint, FISH analysis using a chromosome 3p unique telomere probe identified telomeric 3p material on the distal long arm of the derivative 10 chromosome. This case illustrates the limited value of painting probes to detect small rearrangements, especially those involving terminal chromosome regions.

Overlap of PIV syndrome, VACTERL and Pallister-Hall syndrome: clinical and molecular analysis

The polydactyly, imperforate anus, vertebral anomalies syndrome (PIV, OMIM 174100) was determined as a distinct syndrome by Say and Gerald in 1968 (Say B, Gerald PS. Lancet 1968: 2: 688). We noted that the features of PIV overlap with the VATER association and Pallister-Hall syndrome (PHS, OMIM 146510), which includes polydactyly, (central or postaxial), shortened fingers, hypoplastic nails, renal anomalies, imperforate anus, and hypothalamic hamartoma. Truncation mutations in GL13, a zinc finger transcription factor gene, have been shown to cause PHS. We performed a molecular evaluation on a patient diagnosed with PIV, whose mother, grandfather, and maternal aunt had similar malformations. We sequenced the GLI3 gene in the patient to determine if she had a mutation. The patient was found to have a deletion in nucleotides 2188-2207 causing a frameshift mutation that predicts a truncated protein product of the gene. Later clinical studies demonstrated that the patient also has a hypothalamic hamartoma, a finding in PHS. We concluded that this family had atypical PHS and not PIV. This result has prompted us to re-evaluate the PIV literature to see if PIV is a valid entity. Based on these data and our examination of the literature, we conclude that PIV is not a valid diagnostic entity. We conclude that patients diagnosed with PIV should be reclassified as having VACTERL, or PHS, or another syndrome with overlapping malformations.

Imperforate anus in Feingold syndrome

A father and daughter had the characteristic findings of Feingold syndrome including microcephaly, short palpebral fissures, brachydactyly with clinodactyly of fifth fingers, and bilateral syndactyly of second to third and fourth to fifth toes. The infant presented with long-gap esophageal atresia without fistula (type A). Her father, who had short stature and learning disabilities, had congenital imperforate anus with a recto-vesical fistula. This is the first report of distal intestinal atresia in Feingold syndrome.

The human homolog of insect-derived growth factor, CECR1, is a candidate gene for features of cat eye syndrome

Cat eye syndrome (CES) is a developmental disorder with multiple organ involvement, associated with the duplication of a 2-Mb region of 22q11.2. Using exon trapping and genomic sequence analysis, we have isolated and characterized a gene, CECR1, that maps to this critical region. The protein encoded by CECR1 is similar to previously identified novel growth factors: IDGF from Sarcophaga peregrina (flesh fly) and MDGF from Aplysia californica (sea hare). The CECR1 gene is alternatively spliced and expressed in numerous tissues, with most abundant expression in human adult heart, lung, lymphoblasts, and placenta as well as fetal lung, liver, and kidney. In situ hybridization of a human embryo shows specific expression in the outflow tract and atrium of the developing heart, the VII/VIII cranial nerve ganglion, and the notochord. The location of this gene in the CES critical region and its embryonic expression suggest that the overexpression of CECR1 may be responsible for at least some features of CES, particularly the heart defects.

Penoscrotal inversion, hypospadias, imperforate anus, facial anomalies, and developmental delay: definition of a new clinical syndrome

We describe a 2-month-old boy with penoscrotal inversion, hypospadias, imperforate anus, facial anomalies, developmental retardation, and a subtelomeric deletion of chromosome 13q. His phenotype with anogenital malformations and characteristic facies closely resembled two unrelated patients with minute deletions of chromosome 13q who we reported earlier. In addition, he had unilateral renal agenesis. We propose that these patients represent a clinically recognizable, novel chromosomal microdeletion syndrome. The findings indicate the presence of a major gene(s) on chromosome 13q33.2qter that regulate(s) the migration and development of ano-reno-genital cells and organs. We speculate that mutations of this developmental gene(s) may also result in more frequent congenital malformations (isolated hypospadias, uterus bicornis, unilateral renal agenesis). Additional studies are needed to further delineate the genetic defect.

Townes-Brocks syndrome and renal dysplasia: a novel mutation in the SALL1 gene

A 14-year-old African-American boy had chronic renal failure and Townes-Brocks syndrome (TBS). There were no affected family members. Features were imperforate anus, rectoperineal fistula, triphalangeal thumb, bifid thumb, rocker bottom feet, bilateral ear tags, satyr ear, sensorineural hearing loss, hypospadias, bilateral renal hypoplasia, and progressive chronic renal failure. Renal and urological anomalies in TBS include renal hypoplasia, renal dysplasia, unilateral renal agenesis, horseshoe kidney, posterior urethral valves, uretero-vesical reflux, and meatal stenosis. TBS is caused by a dominantly inherited defect in the gene encoding the SALL1 putative transcription factor, a protein possibly required for urological, renal, limb, ear, brain, and liver development. This patient had a novel mutation in this gene. The extent of renal involvement in patients with TBS should be evaluated for optimum treatment and prediction of prognosis.

Sacral dysgenesis associated with terminal deletion of chromosome 7q: a report of two families

Most cases of sacral dysgenesis are considered to be sporadic events. We present two families in whom the presence of associated clinical features prompted specific investigation of chromosome 7, leading to the identification of an underlying chromosome 7q deletion causing sacral dysgenesis. All affected individuals had microcephaly and developmental delay. Detailed cytogenetic studies confirmed that all three affected individuals had a deletion of chromosome 7q associated with their sacral dysgenesis, developmental delay and related problems. The three affected patients were studied clinically, radiologically and cytogenetically. Eleven unaffected individuals from the two families were also investigated by genetic studies, specifically evaluating chromosome 7.

CONCLUSION

It is important that detailed family history, evaluation of associated malformations and the overall clinical picture be considered in identifying the underlying diagnosis in cases of anal stenosis/sacral agenesis. The cases we present demonstrate the value of detailed chromosome studies in such situations.

Townes-Brocks syndrome: detection of a SALL1 mutation hot spot and evidence for a position effect in one patient

Townes-Brocks syndrome (TBS) is an autosomal dominant developmental disorder characterized by anal and thumb malformations and by ear anomalies that can affect the three compartments and usually lead to hearing loss. The gene underlying TBS, SALL1, is a human homolog of the Drosophila spalt gene which encodes a transcription factor. A search for SALL1 mutations undertaken in 11 unrelated affected individuals (five familial and six sporadic cases) led to the detection of mutations in nine of them. One nonsense and six different novel frameshift mutations, all located in the second exon, were identified. Together with the previously reported mutations [Kohlhase et al., 1999], they establish that TBS results from haploinsufficiency. The finding of de novo mutations in the sporadic cases is consistent with the proposed complete penetrance of the disease. Moreover, the occurrence of the same 826C>T transition in a CG dimer, in three sporadic cases from the present series and three sporadic cases from the other series [Kohlhase et al., 1999] (i.e., six of the eight mutations identified in sporadic cases), reveals the existence of a mutation hotspot. Six different SALL1 polymorphisms were identified in the course of the present study, three of which are clustered in a particular region of the gene that encodes a stretch of serine residues. Finally, the chromosome 16 breakpoint of a t(5;16)(p15.3;q12.1) translocation carried by a TBS-affected individual was mapped at least 180 kb telomeric to SALL1, thus indicating that a position effect underlies the disease in this individual.

The spectrum of imaging in Currarino triad

The aim of this study was to evaluate the spectrum of findings and the efficacy of different imaging modalities in order to formulate recommendations for diagnostic imaging of Currarino triad (ASP syndrome), including screening of relatives. The imaging films of five female patients (age range 6 weeks to 12 months) were analysed retrospectively. The studied material consisted of US and MRI of the lower spine (5 patients each), lumbosacral plain radiography (4 patients), contrast enema (4 patients), urinary US (2 patients), genitography (1 patient) and myelo-CT (1 patient). Depiction of pathological findings with different imaging modalities was reviewed and validated with special respect to their demonstrability by US. Ultrasonography detected the sacral bony defect as well as the presacral pathology (meningocele and/or tumour) and thereby gave the basic diagnosis in all of the cases. It also depicted tethered cord and urinary tract abnormalities correctly. Magnetic resonance imaging gave a more distinct visualization of pre- and intraspinal pathology with additional demonstration of intraspinal lipoma in two cases. Regarding anorectal and genital malformations, radiographic contrast agent studies had been used in all patients. Two blind-ending retrorectal fistulas, depicted by enema, were missed by MRI. Patients with congenital or early infancy obstipation, anorectal malformations and complex urinary tract malformations should have spinal and pelvic sonography first. A plain film of the sacrum is recommended in equivocal cases. The need for MRI and contrast agent studies depends on the individual pathology, whereas presently MRI has made further radiographic imaging increasingly dispensable. A screening program with lumbosacral US or plain radiography for families with Currarino triad should be obligatory.

VACTERL as primary, polytopic developmental field defects

Previously we proposed that the VACTERL association represents a dysmorphogenetic response of the primary developmental field, i.e., polytopic developmental field defects (DFD). As such, it should conform to the essential attributes of a DFD, namely, heterogeneity, homology, and phylogeneity. To study its heterogeneity, we analyzed the data of the Spanish Collaborative Study of Congenital Malformations (ECEMC). Our results confirm the observations indicating that the different patterns of defects that constitute this entity are not only clinically variable but also causally heterogeneous. This causal heterogeneity, which is of crucial importance in defining developmental fields, gives additional credence to the hypothesis that VACTERL constitutes a primary polytopic DFD.

A genetic study of the human T gene and its exclusion as a major candidate gene for sacral agenesis with anorectal atresia

Sacral agenesis is a heterogeneous group of congenital anomalies in which most cases are sporadic but rare familial forms also occur. Although one gene has been mapped to chromosome 7q36 in families with hemisacrum, associated with anorectal atresia and presacral mass, it is clear that the genetic aetiology of these disorders is complex and other genes remain to be discovered. Some years ago, the idea of T (Brachyury) as a candidate gene for sacral agenesis was raised, because tail abnormalities associated with T and the t complex, on mouse chromosome 17, resemble spinal defects seen in man. The recent cloning and mapping of the human T gene prompted us to re-evaluate this idea. T is a transcription factor essential for the normal development of posterior mesodermal structures. Although the sequence and function of T are highly conserved in evolution, our genetic study shows that the coding region of the human gene is highly polymorphic. Three common variable amino acid sites in known functional domains have been identified: Gly356Ser, Asn369Ser, and Gly177Asp. For the latter variant, functional studies have shown that the presence of Asp at residue 177 reduces the stability of T dimer formation. A search for rare mutation of T in 28 selected patients with sacral agenesis/anorectal atresia identified a novel, rare variant in one patient and her mother. This mutation leads to an amino acid change within a conserved activation domain. While the functional significance of this single mutation requires further investigation, we can conclude from our studies that if T has a role in the aetiology of sacral agenesis, its contribution is small in this particular set of patients. However, we cannot exclude a more major role in other forms of sacral defect.

An unusual case of the complete Currarino triad: case report, discussion of the literature and the embryogenic implications

OBJECTIVE AND IMPORTANCE

We present and illustrate an unusual case of the complete familial Currarino triad (an association between a bony sacral defect, a presacral mass, and an anorectal malformation) in which the teratoma arose from the conus medullaris and contained mature neurons, glia, and branching ependymal canals that were in communication with a terminal syrinx. The embryogenic implications are discussed.

CLINICAL PRESENTATION

The patient was a term neonate when discovered to have imperforate anus. Further workup revealed lumbosacral dysraphism with a presacral mass, a rectovaginal fistula, and a single pelvic kidney. The family pedigree revealed a familial transmission pattern; the patient had a second cousin with anal atresia and a first cousin with similar sacral anomalies. The motor level was L4 with trace L5, and there was absent sensation in the sacral dermatomes.

INTERVENTION

A diverting colostomy was performed on Day 14, and the infant returned at 3 months of age to undergo near-total resection through the previous abdominal approach. Only a subtotal resection was possible because the mass arose from the low-lying conus and was firmly adherent to the sacral nerve roots and iliac vessel. Follow-up magnetic resonance imaging performed 18 months after surgery revealed that the residual tumor had not progressed.

CONCLUSION

Complete Currarino triad is rare and is familial in half of the cases. The special features of the tumor in our case were the presence of mature neurons with ependymal canals and its origin from the conus. The possible embryogenesis may provide evidence that the caudal notochord is important for organized secondary neurulation.