Williams, Eli S.

Background/Objective: Although most melanocytic lesions are diagnosed as benign or malignant by histopathologic evaluation, with or without the aid of immunohistochemistry, diagnosis may remain uncertain in a minority of cases. Assessment of copy number abnormalities (CNAs) may provide sufficient additional evidence to favor either a benign or malignant diagnosis in both pediatric and adult cases and in melanocytic lesions of various subtypes, including Spitzoid, mucosal, and acral. CNAs are common in melanomas, while they are rare, with few exceptions, in benign lesions. Detection of CNAs by fluorescence in situ hybridization (FISH) and chromosomal microarray (CMA) has been well established for melanocytic lesions, with advantages and disadvantages for each. The objective of this meta-analysis was to evaluate the utility of CNA testing for the diagnosis of melanoma, across subtypes, when a lesion remains ambiguous after histopathologic and immunohistochemical assessment. In addition, the utility of CNAs to determine prognosis in established diagnoses of melanoma was also evaluated. Methods: The Cancer Genomics Consortium Working Group for Melanocytic Lesions reviewed published data from January 1998 through September 2022 of CNAs in melanocytic lesions detected by either FISH or CMA and conducted a meta-analysis of the findings. Results: Specific abnormalities common in primary cutaneous melanomas of various subtypes and uveal melanomas were enumerated. Differences in CNAs found in primary versus metastatic lesions were also determined, and published evidence for prognosis was summarized. Conclusions: The working group established evidence-based recommendations for the use of CNA testing for evaluation of ambiguous melanocytic lesions.

AbstractBackgroundMutations in the parkin gene (PRKN) are the most commonly identified genetic factors in early onset Parkinson disease (EOPD), with biallelic mutations, resulting in a clinical phenotype. However, normal variation is also common in PRKN, particularly in the form of copy number variation (CNV), challenging interpretation of genetic testing results. Here we report a case of a 29‐year‐old male with EOPD and two deletions in PRKN detected by chromosomal microarray (CMA).MethodsThe proband was clinically examined by a neurologist for postural instability with frequent falls, bradykinesia, gait freezing with festination, and hypophonia. Chromosomal microarray analysis (CMA) was performed on the proband and his parents using the Affymetrix CytoScan HD microarray. Subsequent fluorescence in situ hybridization (FISH) was performed on the proband and both parents.ResultsChromosomal microarray detected the presence of two deletions of PRKN in the proband. Parental CMA analysis was performed to determine the clinical significance of this finding, as well as to demonstrate phase of these deletions. Parental CMA revealed that one deletion was paternally inherited and one deletion was de novo. A custom FISH approach was then successfully used to phase the deletions.ConclusionChromosomal microarray and fluorescence in situ hybridization analysis of this trio identified two deletions in PRKN occurring in trans, providing a genetic etiology for the clinical diagnosis of EOPD. The determination of inheritance and phase of the deletions was critical to the proper interpretation of these results. These findings highlight the utility of CMA in the detection of clinically relevant CNVs in cases of EOPD, and also serve to emphasize the importance of follow‐up FISH and parental testing.