Vaginal atresia and Bardet-Biedl syndrome association: a component or a distinct entity?

A case of McKusick-Kaufman syndrome

McKusick-Kaufman syndrome (MKS) is an autosomal recessive multiple malformation syndrome characterized by hydrometrocolpos (HMC) and postaxial polydactyly (PAP). We report a case of a female child with MKS who was transferred to the neonatal intensive care unit of Seoul National University Children's Hospital on her 15th day of life for further evaluation and management of an abdominal cystic mass. She underwent abdominal sonography, magnetic resonance imaging, genitography and cystoscopy which confirmed HMC with a transverse vaginal septum. X-rays of the hand and foot showed bony fusion of the left third and fourth metacarpal bones, right fourth dysplastic metacarpal bone and phalanx, right PAP and hypoplastic left foot with left fourth and fifth dysplastic metatarsal bones. In addition, she had soft palate cleft, mild hydronephroses of both kidneys, hypoplastic right kidney with ectopic location and mild rotation, uterine didelphys with transverse vaginal septum and low-type imperforated anus. She was temporarily treated with ultrasound-guided transurethral aspiration of the HMC. Our patient with HMC and PAP was diagnosed with MKS because she has two typical abnormality of MKS and she has no definite complications of retinal disease, learning disability, obesity and renal failure that develop in Bardet-Biedl syndrome, but not in MKS until 33 months of age. Here, we describe a case of a Korean patient with MKS.

Hydrometrocolpos and acute renal failure: a rare neonatal presentation of Bardet-Biedl syndrome

The presence of hydrometrocolpos and postaxial polydactyly in a neonate can be caused by two genetic conditions; namely, McKusick-Kaufman syndrome and Bardet-Biedl syndrome. There are no distinct clinical features that allow discrimination between the two syndromes, as the cardinal features of rod-cone dystrophy, obesity, learning disability and renal dysfunction in Bardet-Biedl syndrome are age dependent. McKusick-Kaufman syndrome is characterized by vaginal atresia with hydrometrocolpos, postaxial polydactyly and congenital heart defect. Here we report an unusual presentation of Bardet-Biedl syndrome: a neonate born in a consanguineous family having an older sibling diagnosed with Bardet-Biedl syndrome presenting with postaxial polydactyly and vaginal atresia; the latter causing hydrometrocolpos, hydronephrosis and renal failure. Relief of urinary obstruction by exploratory laparotomy and aspiration of fluid, and vaginal reconstruction gradually reversed the hydronephrosis and renal failure. The patient developed end-stage renal failure towards the end of her first decade, possibly due to underlying renal pathology associated with Bardet-Biedl syndrome.

[Update on Bardet-Biedl syndrome]

Until recently, Bardet-Biedl syndrome was considered as a classic autosomal recessive condition. The disorder is defined by the association of the following clinical features: retinitis pigmentosa, polydactyly, obesity, hypogonadism, and possible mental retardation. This syndrome leads to multiple handicaps (visual impairment, complications of obesity, kidney failure, endocrine dysfunction). This condition, apparently clearly defined from a clinical point of view, appears to be genetically heterogenous. To date, six different genes have been identified: BBS1, BBS2, BBS4, BBS6, BBS7 and BBS8. Interestingly, this condition has recently been linked to a failure of cellular ciliogenesis. Moreover, this disorder is characterized by an additional degree of complexity, as it is the first example of triallelic inheritance described in human beings. However, this new finding appears to be less frequent than expected in this syndrome.

The molecular genetics of Bardet–Biedl syndrome

Bardet-Biedl syndrome (BBS) has been shown to be a genetically heterogeneous disorder involving genes mapping to at least six known loci. One BBS gene (MKKS) has been identified and the form of the disorder caused by this gene is allelic to McKusick-Kaufman syndrome. MKKS codes for a putative chaperonin, suggesting that other BBS genes may also code for components of chaperone complexes or be substrates of chaperone function.