TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: CDKZ    
CDKN1C Gene, Full Gene Analysis, Varies

Useful For Suggests clinical disorders or settings where the test may be helpful

Confirming a clinical diagnosis of Beckwith-Wiedemann syndrome following a normal result on methylation analysis

 

Confirming a clinical diagnosis of intrauterine growth restriction, metaphyseal dysplasia, adrenal hypoplasia congenita, and genital anomalies (IMAGe) syndrome

 

Confirming a clinical diagnosis of Russell-Silver syndrome following a normal result on methylation analysis and uniparental disomy (UPD) 7 studies.

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

If skin biopsy is received, fibroblast culture for genetic test will be added and charged separately.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

The CDKN1C gene is an imprinted gene that has been associated with Beckwith-Wiedemann syndrome (BWS), intrauterine growth restriction, metaphyseal dysplasia, adrenal hypoplasia congenita, and genital anomalies (IMAGe) syndrome, and Russell-Silver syndrome (RSS). Imprinting describes a difference in gene expression based on parent of origin. The majority of autosomal genes exhibit biallelic (maternal and paternal) expression, whereas imprinted genes are normally expressed from only one parent. CDKN1C is typically expressed on the maternally inherited allele.

 

Beckwith-Wiedemann Syndrome:

BWS is a disorder characterized by prenatal and/or postnatal overgrowth, neonatal hypoglycemia, congenital malformations, and an increased risk for embryonal tumors. Physical findings are variable and can include abdominal wall defects, macroglossia, and hemihyperplasia. The predisposition for tumor development is associated with specific tumor types such as adrenal carcinoma, nephroblastoma (Wilms tumor), hepatoblastoma, and rhabdomyosarcoma. In infancy, BWS has a mortality rate of approximately 20%.

 

Most cases of BWS are caused by hypomethylation of LIT1, paternal uniparental disomy of chromosome 11, or hypermethylation of H19. Approximately 5% to 10% of sporadic BWS cases and approximately 40% of BWS cases with a positive family history are caused by CDKN1C variants. The appropriate first-tier test in the evaluation of a possible diagnosis of BWS is BWRS / Beckwith-Wiedemann Syndrome/Russell-Silver Syndrome Molecular Analysis, Varies. This test may be considered when the results of BWS methylation analysis are negative, and there is still a strong clinical suspicion of BWS.

 

Intrauterine Growth Restriction, Metaphyseal Dysplasia, Adrenal Hypoplasia Congenita, and Genital Anomalies Syndrome:

Variants in the CDKN1C gene have also been associated with IMAGe syndrome). The CDKN1C variants associated with IMAGe syndrome tend to be missense variants occurring in the PCNA-binding domain of the gene. Not every individual with a clinical diagnosis of IMAGe syndrome will have an identifiable CDKN1C variant.

 

Russell-Silver Syndrome:

RSS is a rare genetic condition with an incidence of approximately 1 in 100,000. RSS is characterized by pre- and postnatal growth retardation with normal head circumference, characteristic facies, fifth finger clinodactyly, and asymmetry of the face, body, and/or limbs. Less commonly observed clinical features include cafe au lait spots, genitourinary anomalies, motor, speech, cognitive delays, and hypoglycemia.

 

RSS is a genetically heterogeneous condition that is associated with genetic and epigenetic alterations at chromosome 7 and the chromosome 11p15.5 region. The majority of cases of RSS are sporadic, although familial cases have been reported. The etiology of sporadic cases of RSS includes: hypomethylation of IC1 (H19), maternal uniparental disomy (UPD) of chromosome 7, 11p15.5 duplications (rare), and chromosome 7 duplications (rare).

 

CDKN1C variants have recently been identified as a cause of RSS in some families. This test may be considered when results of RSS methylation analysis and UPD 7 studies are negative and there is still a strong clinical suspicion of RSS.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

All detected alterations are evaluated according to American College of Medical Genetics and Genomics (ACMG) recommendations.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

A small percentage of individuals who are carriers or have a diagnosis of Beckwith-Wiedemann syndrome, intrauterine growth restriction, metaphyseal dysplasia, adrenal hypoplasia congenita and genital anomalies (IMAGe) syndrome, or Russell-Silver syndrome caused by CDKN1C may have a variant that is not identified by this method (eg, large genomic deletions, promoter variants). The absence of a variant, therefore, does not eliminate the possibility of positive carrier status or the diagnosis of Beckwith-Wiedemann syndrome, IMAGe syndrome, or Russell-Silver syndrome. For carrier testing, it is important to first document the presence of a CDKN1C gene variant in an affected family member.

 

In some cases, DNA alterations of undetermined significance may be identified.

 

Rare polymorphisms exist that could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, additional testing should be considered.

 

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in our interpretation of results may occur if information given is inaccurate or incomplete.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015 May;17(5):405-424

2. DeBaun MR, Niemitz EL, McNeil DE, Brandenburg SA, Lee MP, Feinberg AP: Epigenetic alterations of H19 and LIT1 distinguish patients with Beckwith-Wiedemann Syndrome with cancer and birth defects. Am J Hum Genet. 2002;70:604-611

3. Choufani S, Shuman C, Weksberg R: Beckwith-Wiedemann Syndrome. Am J Med Genet. 2010;154C:343-354

4. Romanelli V, Belinchon A, Benito-Sanz S, et al: CDKN1C (p57[Kip2]) analysis in Beckwith-Wiedemann syndrome (BWS) patients: Genotype-phenotype correlations, novel mutations, and polymorphisms. Am J Med Genet A. 2010;152A:1390-1397

5. Lam WWK, Hatada I, Ohishi S, et al: Analysis of germline CDKNIC (p57[Kip2]) mutations in familial and sporadic Beckwith-Wiedemann syndrome (BWS) provides a novel genotype-phenotype correlation. J Med Genet. 1999;36:518-523

6. Arboleda VA, Lee H, Parnaik R, et al: Mutations in the PCNA-binding domain of CDKN1C cause IMAGe syndrome. Nat Genet. 2012;44(7):788-792

Special Instructions Library of PDFs including pertinent information and forms related to the test