Clinical Guidance

Current information about genotype-phenotype correlations in Cant syndrome is limited; no significant clinically relevant genotype-phenotype correlations for ABCC9 or KCNJ8 have been identified.

Source: GeneReviews — "Cant Syndrome"

Penetrance

Penetrance for Cant syndrome reported thus far appears to be complete although with variable expression . In a few families, somatic mosaicism for an ABCC9 variant has been identified in one of the parents, resulting in much milder phenotypic manifestations in that individual [; DK Grange, unpublished data].

Source: GeneReviews — "Cant Syndrome"

Diagnostic Criteria

No formal diagnostic criteria for Cant syndrome have been established.

Suggestive Findings

Cant syndrome should be suspected in probands with the following clinical and imaging findings and family history.

Clinical findings

• Congenital hypertrichosis: excess hair growth on scalp, forehead, face, back, and limbs (See and .)

• Craniofacial dysmorphic features: coarse facial features, epicanthal folds, broad nasal bridge, anteverted nares, long philtrum, thick vermilion of the upper and lower lips, wide mouth, and macroglossia (See .)

Imaging findings

Source: GeneReviews — "Cant Syndrome"

Differential Diagnosis

Genetic Disorders Table 4. Cant Syndrome: Differential Diagnosis

Management Guidelines

No clinical practice guidelines for Cant syndrome have been published. In the absence of published guidelines, the following recommendations are based on the authors' personal experience managing individuals with this disorder.

Evaluations Following Initial Diagnosis

To establish the extent of disease and needs in an individual diagnosed with Cant syndrome, the evaluations summarized (if not performed as part of the evaluation that led to the diagnosis) are recommended.

Table 5.

Cant Syndrome: Recommended Evaluations Following Initial Diagnosis

System/Concern | Evaluation | Comment

Cardiac

| Cardiology assessment to include echocardiogram electrocardiogram | • Consider cardiac MRI.

• Assessment for pulmonary hypertension should be guided by cardiologist as needed.

Neurologic

| • Assessment for headaches seizures

• Neurologic exam

• EEG if seizures are suspected

|

Brain MRI w/MRA MRV | Should be considered for all persons, but esp if there is history of headaches, migraine headaches, or hemiparesis

Development

| Developmental eval for infants young children |

Neuropsychological eval for older persons | Esp for those w/concern for ASD, ADHD, OCD, or depression

Vascular/

Lymphatic

| Assessment for peripheral swelling lymphedema |

GERD | In those w/clinical manifestations of GERD, swallow study might be considered depending on symptoms. |

Skeletal

| • Radiographic skeletal survey as needed to assess for bone abnormalities

• Eval for scoliosis

| A full skeletal survey may not be needed in all persons.

Genetic

Source: GeneReviews — "Cant Syndrome"

Clinical Guidance

Avoid the following:

• Minoxidil

• Diazoxide

• Angiotensin-converting enzyme inhibitors

Source: GeneReviews — "Cant Syndrome"

Therapies Under Investigation

Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Source: GeneReviews — "Cant Syndrome"

Surveillance Guidelines

To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations summarized in are recommended. Table 7. Cant Syndrome: Recommended Surveillance

Source: GeneReviews — "Cant Syndrome"