Clinical Guidance

McKusick-Kaufman syndrome (MKS), defined as hydrometrocolpos (HMC) and postaxial polydactyly (PAP) without the development of the age-dependent features of BBS, was first diagnosed in a large Amish family . Although the MKS phenotype is very rare, it has been presumed to be pan ethnic following descriptions of HMC in association with polydactyly in numerous ancestries. In the Amish population, variable expressivity for MKS has been described: 70% of affected females have HMC, 60% of affected individuals of both sexes have PAP, and 15% of affected individuals of both sexes have congenital heart disease (CHD) . Of note, many individuals with HMC and PAP diagnosed as having MKS have been reported at an age too young to manifest the age-dependent features of BBS . The true incidence of physical findings associated with the MKS phenotype alone is therefore unknown. shows the most frequent associated features in 49 individuals of Amish and non-Amish ethnicity who were diagnosed with MKS; 75% were diagnosed at birth and 98% by age six months . Of these individuals, 44 were female and five were male. No similar large studies have been realized more recently and the majority of recent case reports have comprised single individuals with HMC reported in the first year of life . The degree of similarity of the phenotype between the Amish and non-Amish population is unclear and has not been systematically studied; in addition, it is not known if these individuals would have developed manifestations of BBS as they aged. The incidence of genital findings in males has also been difficult to establish outside the Amish population due to the rarity of the condition, but in 11 males who had affected sisters or other female relatives diagnosed with MKS, polydactyly was present in all cases and only one had genital abnormalities comprising cryptorchidism and hypospadias ; however, the incidence of BBS among these individuals is not known. Table 2. Phenotypic Features of Individuals with McKusick-Kaufman Syndrome (MKS) Finding | # of Individuals (%) Genitourinary malformations in females

Diagnostic Criteria

No consensus clinical diagnostic criteria for McKusick-Kaufman syndrome (MKS) have been published.

Suggestive Findings

Diagnosis of McKusick-Kaufman syndrome (MKS) should be suspected in individuals with the following features.

In females

• Hydrometrocolpos (HMC)*

• Postaxial polydactyly (PAP)**

Management Guidelines

No clinical practice guidelines for MKS have been published. Evaluations Following Initial Diagnosis To establish the extent of disease and needs in an individual diagnosed with McKusick-Kaufman syndrome (MKS), the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended. Table 4. Recommended Evaluations Following Initial Diagnosis in Individuals with McKusick-Kaufman Syndrome (MKS)

Surveillance Guidelines

Table 6.

Recommended Surveillance for Individuals with McKusick-Kaufman Syndrome (MKS)

System/Concern | Evaluation | Frequency

Hydrometrocolpos

| Watch for later complications of surgery for HMC, incl recurrent urinary tract infections re-stenosis infection of vaginal tract. | No monitoring; prompt eval of symptoms signs of abdominal distention