Case Of Bardet-Biedl Syndrome Research Articles

Molecular Analysis of Bardet-Biedl Syndrome Families: Report of 21 Novel Mutations in 10 Genes

Bardet-Biedl syndrome (BBS) is genetically heterogeneous with 15 BBS genes currently identified, accounting for approximately 70% of cases. The aim of our study was to define further the spectrum of BBS mutations in a cohort of 44 European-derived American, 8 Tunisian, 1 Arabic, and 2 Pakistani families (55 families in total) with BBS. A total of 142 exons of the first 12 BBS-causing genes were screened by dideoxy sequencing. Cases in which no mutations were found were then screened for BBS13, BBS14, BBS15, RPGRIP1L, CC2D2A, NPHP3, TMEM67, and INPP5E. Forty-three mutations, including 8 frameshift mutations, 10 nonsense mutations, 4 splice site mutations, 1 deletion, and 20 potentially or probably pathogenic missense variations, were identified in 46 of the 55 families studied (84%). Of these, 21 (2 frameshift mutations, 4 nonsense mutations, 4 splice site mutations, 1 deletion, and 10 missense variations) were novel. The molecular genetic findings raised the possibility of triallelic inheritance in 7 Caucasian families, 1 Arabian family, and 1 Tunisian patient. No mutations were detected for BBS4, BBS11, BBS13, BBS14, BBS15, RPGRIP1L, CC2D2A, NPHP3, TMEM67, or INPP5E. This mutational analysis extends the spectrum of known BBS mutations. Identification of 21 novel mutations highlights the genetic heterogeneity of this disorder. Differences in European and Tunisian patients, including the high frequency of the M390R mutation in Europeans, emphasize the population specificity of BBS mutations with potential diagnostic implications. The existence of some BBS cases without mutations in any currently identified BBS genes suggests further genetic heterogeneity.

Bardet-Biedl Syndrome With Gait Ataxia: A Case Report

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive condition characterized by retinitis pigmentosa, dysphormic extremities, central obesity, ataxia, and renal involvement1. We report probably the first case of BBS with documented gait ataxia from South East Asia. The diagnosis had been missed many times until the patient presented at our hospital. The relevant literature has also been reviewed.

Treatment of Gingival Overgrowth in a Child With Bardet‐Biedl Syndrome

Bardet-Biedl syndrome (BBS) is a rare, heterogeneous, autosomal recessive condition, primarily characterized by polydactyly, obesity, mental retardation, hypogonadism, retinopathy, and renal failure. Dental anomalies, regarded as secondary manifestations, include hypodontia, microdontia, short roots, and deep palate. Few reports in the literature have described the oral manifestations of BBS. This article reports a case of BBS in a boy who presented some typical oral manifestations added to a generalized gingival overgrowth, an anomaly that had not been reported previously in patients with this syndrome. A 12-year-old white male presented with a diagnosis of BBS and chief complaint of gingival enlargement in the anterior segment of both arcades. The treatment plan included surgical removal of the overgrown gingiva followed by orthodontic therapy. The excised tissues were submitted to histologic analysis. There was no sign of recurrence 1 year after gingivectomy. Histopathology revealed a dense connective tissue with a mild inflammatory infiltrate, irregularly arranged fiber bundles, and epithelial acanthosis, which is characteristic of gingival overgrowth. The gingival overgrowth was treated successfully by gingivectomy. The periodontal surgery minimized the functional, social, and emotional consequences of the oral manifestation associated with the syndrome.

Atypical association of Duane retraction syndrome and Bardet Biedl syndrome

Duane's retraction syndrome (DRS) includes changes in palpebral fissure width along with restriction of ocular motility. Bardet Biedl syndrome (BBS) includes presence of retinitis pigmentosa (RP) with obesity, mental retardation, polydactyly and renal abnormalities. We report a case of rare association of DRS with BBS in a seven-year-old child. The ocular motility examination revealed left DRS with esotropia. Fundus examination revealed findings characteristic of an atypical retinitis pigmentosa. The electro-retinogram waveforms were extinguished both for rods and cones. He was diagnosed as a case of BBS on the basis of the ophthalmological findings plus association with the systemic features of obesity, polydactyly, hypogonadism, mental retardation and renal abnormalities. This case gives further evidence of the fact that BBS may be associated with abnormalities of eye movements.

Bardet-Biedl syndrome with end-stage kidney disease: A case report and review of literature

Bardet-Biedl syndrome (BBS) is a rare autosomal recessive condition characterized by retinitis pigmentosa, postaxial polydactyly, central obesity, and renal involvement. Renal failure is the commonest cause of death. We report the first case of BBS with documented end-stage kidney disease from India. The diagnosis had been missed until the patient presented at our hospital. The relevant literature has also been reviewed.

Bardet-Biedl Syndrome in an African-American Patient: Should the Diagnostic Criteria Be Expanded to Include Hydrometrocolpos?

Bardet-Biedl Syndrome (BBS) is a multisystemic disorder diagnosed on the basis of a combination of primary and secondary clinical features that include retinal dystrophy, obesity, polydactyly, cognitive dysfunction, and renal malformations. We report a unique case of BBS in a 13-year old girl of African-American descent who presented with retinitis pigmentosa, obesity, polydactyly, learning disabilities, precocious puberty, hypertension, renal cysts, and Hirschprung disease. Further evaluation revealed a history of precocious puberty, which is antithetical to the common manifestations of BBS, while neuroimaging was suggestive of periventricular leukomalacia and neuro-electrophysiologic studies revealed diffuse cerebral disturbance, which may contribute to her neurological abnormalities. The patient was also diagnosed with hydrometrocolpos, a finding typical of McKusick-Kaufman Syndrome (MKKS) but infrequent in other disorders. This observation, together with recent findings in some mouse models of BBS, raises the question of whether hydrometrocolpos should be considered as an additional diagnostic criterion for BBS to be used in females in parallel to the criterion of hypogonadism in males, thereby improving diagnostic sensitivity.

Identification of a Novel BBS Gene ( BBS12) Highlights the Major Role of a Vertebrate-Specific Branch of Chaperonin-Related Proteins in Bardet-Biedl Syndrome

Bardet-Biedl syndrome (BBS) is primarily an autosomal recessive ciliopathy characterized by progressive retinal degeneration, obesity, cognitive impairment, polydactyly, and kidney anomalies. The disorder is genetically heterogeneous, with 11 BBS genes identified to date, which account for ~70% of affected families. We have combined single-nucleotide-polymorphism array homozygosity mapping with in silico analysis to identify a new BBS gene, BBS12. Patients from two Gypsy families were homozygous and haploidentical in a 6-Mb region of chromosome 4q27. FLJ35630 was selected as a candidate gene, because it was predicted to encode a protein with similarity to members of the type II chaperonin superfamily, which includes BBS6 and BBS10. We found pathogenic mutations in both Gypsy families, as well as in 14 other families of various ethnic backgrounds, indicating that BBS12 accounts for approximately 5% of all BBS cases. BBS12 is vertebrate specific and, together with BBS6 and BBS10, defines a novel branch of the type II chaperonin superfamily. These three genes are characterized by unusually rapid evolution and are likely to perform ciliary functions specific to vertebrates that are important in the pathophysiology of the syndrome, and together they account for about one-third of the total BBS mutational load. Consistent with this notion, suppression of each family member in zebrafish yielded gastrulation-movement defects characteristic of other BBS morphants, whereas simultaneous suppression of all three members resulted in severely affected embryos, possibly hinting at partial functional redundancy within this protein family.

Mkks-null mice have a phenotype resembling Bardet–Biedl syndrome

McKusick-Kaufman syndrome (MKS) is an autosomal recessive disorder characterized by post-axial polydactyly, congenital heart defects and hydrometrocolpos, a congenital structural abnormality of female genitalia. Mutations in the MKKS gene have also been shown to cause some cases of Bardet-Biedl syndrome (BBS) which is characterized by obesity, pigmentary retinopathy, polydactyly, renal abnormalities and hypogenitalism with secondary features of hypertension and diabetes. Although there is overlap in clinical features between MKS and BBS, MKS patients are not obese and do not develop retinopathy or have learning disabilities. To further explore the pathophysiology of BBS and the related disorder MKS, we have developed an Mkks(-/-) mouse model. This model shows that the absence of Mkks leads to retinal degeneration through apoptosis, failure of spermatozoa flagella formation, elevated blood pressure and obesity. The obesity is associated with hyperphagia and decreased activity. In addition, neurological screening reveals deficits in olfaction and social dominance. The mice do not have polydactyly or vaginal abnormalities. The phenotype of the Mkks(-/-) mice closely resembles the phenotype of other mouse models of BBS (Bbs2(-/-) and Bbs4(-/-)). These observations suggest that the complete absence of MKKS leads to BBS while the MKS phenotype is likely to be due to specific mutations.

Antenatal Presentation of Bardet-Biedl Syndrome May Mimic Meckel Syndrome

Bardet-Biedl syndrome (BBS) is a multisystemic disorder characterized by postaxial polydactyly, progressive retinal dystrophy, obesity, hypogonadism, renal dysfunction, and learning difficulty. Other manifestations include diabetes mellitus, heart disease, hepatic fibrosis, and neurological features. The condition is genetically heterogeneous, and eight genes (BBS1-BBS8) have been identified to date. A mutation of the BBS1 gene on chromosome 11q13 is observed in 30%-40% of BBS cases. In addition, a complex triallelic inheritance has been established in this disorder--that is, in some families, three mutations at two BBS loci are necessary for the disease to be expressed. The clinical features of BBS that can be observed at birth are polydactyly, kidney anomaly, hepatic fibrosis, and genital and heart malformations. Interestingly, polydactyly, cystic kidneys, and liver anomalies (hepatic fibrosis with bile-duct proliferation) are also observed in Meckel syndrome, along with occipital encephalocele. Therefore, we decided to sequence the eight BBS genes in a series of 13 antenatal cases presenting with cystic kidneys and polydactyly and/or hepatic fibrosis but no encephalocele. These fetuses were mostly diagnosed as having Meckel or "Meckel-like" syndrome. In six cases, we identified a recessive mutation in a BBS gene (three in BBS2, two in BBS4, and one in BBS6). We found a heterozygous BBS6 mutation in three additional cases. No BBS1, BBS3, BBS5, BBS7, or BBS8 mutations were identified in our series. These results suggest that the antenatal presentation of BBS may mimic Meckel syndrome.

Síndrome de Bardet-Biedl: relato de dois casos

A síndrome de Bardet-Biedl é doença de herança autossômica recessiva caracterizada por distrofia retiniana, polidactilia, obesidade, retardo mental e hipogenitalismo. Um ou mais dos achados acima que caracterizam a síndrome podem estar ausentes, mas a distrofia retiniana é achado consistente. Esta se manifesta clinicamente na infância com progressiva perda visual, causando grave dificuldade visual na adolescência. Os autores descrevem dois casos de síndrome de Bardet-Biedl, os resultados da acuidade visual, biomicroscopia, oftalmoscopia, angiografia, campo visual e eletrorretinograma. Foi realizada revisão bibliográfica com ênfase na identificação dos sinais sistêmicos, envolvimento ocular, testes eletrofisiológicos e avaliação genética.

Mutations in MKKS cause Bardet-Biedl syndrome.

Bardet-Biedl syndrome (BBS) is an autosomal recessive disorder with locus heterogeneity. None of the 'responsible' genes have previously been identified. Some BBS cases (approximately 10%) remain unassigned to the five previously mapped loci. McKusick-Kaufma syndrome (MKS) includes hydrometrocolpos, postaxial polydactyly and congenital heart disease, and is also inherited in an autosomal recessive manner. We ascertained 34 unrelated probands with classic features of BBS including retinitis pigmentosa (RP), obesity and polydactyly. The probands were from families unsuitable for linkage because of family size. We found MKKS mutations in four typical BBS probands (Table 1). The first is a 13-year-old Hispanic girl with severe RP, PAP, mental retardation and obesity (BMI >40). She was a compound heterozygote for a missense (1042GA, G52D) and a nonsense (1679TA, Y264stop) mutation in exon 3. Cloning and sequencing of the separate alleles confirmed that the mutations were present in trans. A second BBS proband (from Newfoundland), born to consanguineous parents, was homozygous for two deletions (1316delC and 1324-1326delGTA) in exon 3, predicting a frameshift. An affected brother was also homozygous for the deletions, whereas an unaffected sibling had two normal copies of MKKS. Both the proband and her affected brother had RP, PAP, mild mental retardation, morbid obesity (BMI >50 and 37, respectively), lobulated kidneys with prominent calyces and diabetes mellitus (diagnosed at ages 33 and 30, respectively). A deceased sister (DNA unavailable) had similar phenotypic features (RP with blindness by age 13, BMI >45, abnormal glucose tolerance test and IQ=64, vaginal atresia and syndactyly of both feet). Both parents and the maternal grandfather were heterozygous for the deletions. Genotyping with markers from the MKKS region confirmed homozygosity at 20p12 in both affected individuals.

Genetic and Clinical Findings in Fifty-Two Cases of Bardet-Biedl Syndrome in 23 Families

A systematic clinical and psychiatric examination of MR patients at NIMHANS led to the diagnoses of 44 cases of BB Syndrome in 23 families of which 8 had died during infancy. Family history revealed 8 more similar cases in their relatives of which 5 had died. 1 Consanguinity was noted in 80% of the families. Psychoses, deaf mutism and simian crease were some of the associated clinical features in these cases.

A Disorder Related to Bardet-Biedl Syndrome

To the Editor. —We read with interest the article by Schachat and Maumenee entitled Syndrome and Related Disorders, published in the FebruaryArchives(1982;100:285-288). Drs Schachat and Maumenee should be congratulated for summarizing the present state of knowledge on these syndromes. Last year, we reported two cases of Bardet-Biedl syndrome that were seen at the Hospital for the Prevention of Blindness in Mexico City. 1 We agree with Drs Schachat and Maumenee that their case represents a new entity combining ocular and auditory defects, mental retardation, genital hypoplasia, obesity, and polydactyly. A second case has been reported in the literature to help establish the constancy of this new entity.

Urographic findings in the Bardet-Biedl syndrome, formerly the Laurence-Moon-Biedl syndrome.

Six cases of Bardet-Biedl syndrome are presented. Common findings in this syndrome include mental retardation, pigmentary retinopathy, obesity, and hypogonadism. Uremia is stated to be the cause of death in more than one-third of reported cases. In almost all cases, cystic spaces communicating with the collecting system are demonstrated by excretory urography. The origin of these spaces is not understood. Assessment of the urinary tract by excretory urography and probably by catheter cystography should be undertaken in all patients with this syndrome to assist in proper management.