{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,25]],"date-time":"2026-07-25T04:21:38Z","timestamp":1784953298336,"version":"3.55.0"},"reference-count":8,"publisher":"American Academy of Pediatrics (AAP)","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2013,6,1]]},"abstract":"<jats:p>The presence of 2 distinct populations of somatic or germline cells within a single individual harboring different genotypes is termed mosaicism. Recent reports suggest that parental mosaicism is involved in the heritability of type 1 Timothy syndrome (TS1), an extremely rare and life-threatening multisystem disorder characterized by severe QT interval prolongation, syndactyly, and several other complications. Although full TS1 is caused by a single missense mutation in the CACNA1C-encoded cardiac calcium channel, mosaic TS1 parents can display isolated syndactyly without additional phenotypic manifestations. A newborn boy presented with syndactyly at birth. The presence of syndactyly in his mother led to a diagnosis of benign familial syndactyly. However, at 9 months of age, during his first syndactyly-corrective surgery, intraoperative electrocardiograms revealed extreme QT prolongation and 2:1 atrioventricular block. A comprehensive cardiac evaluation was performed, and both mother and child were tested genetically, confirming a clinical suspicion of TS1. Only the patient tested positive for the TS1 mutation; however, more extensive molecular testing revealed a limited presence of the mutation in maternally-derived DNA. This case illustrates the potential of parental mosaicism to confound the diagnosis of potentially life-threatening genetic diseases, such as TS1. Here, a mother with a partial TS1 phenotype and genetically confirmed mosaicism transmitted the TS1-causative mutation to her son, resulting in fully expressive TS1. Thus, a shared partial phenotype should not be dismissed as a benign or insignificant finding, but should be evaluated further to rule out the possibility of parental mosaicism concealing a potentially fatal heritable disease.<\/jats:p>","DOI":"10.1542\/peds.2012-2941","type":"journal-article","created":{"date-parts":[[2013,5,21]],"date-time":"2013-05-21T00:48:16Z","timestamp":1369097296000},"page":"e1991-e1995","source":"Crossref","is-referenced-by-count":33,"title":["Maternal Mosaicism Confounds the Neonatal Diagnosis of Type 1 Timothy Syndrome"],"prefix":"10.1542","volume":"131","author":[{"given":"Keith A.","family":"Dufendach","sequence":"first","affiliation":[{"name":"Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John R.","family":"Giudicessi","sequence":"additional","affiliation":[{"name":"Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory,"},{"name":"Mayo Medical School, and"},{"name":"Mayo Graduate School, Mayo Clinic, Rochester, Minnesota"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nicole J.","family":"Boczek","sequence":"additional","affiliation":[{"name":"Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory,"},{"name":"Mayo Graduate School, Mayo Clinic, Rochester, Minnesota"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael J.","family":"Ackerman","sequence":"additional","affiliation":[{"name":"Departments of Medicine (Division of Cardiovascular Diseases), Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory,"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"417","published-online":{"date-parts":[[2013,6,1]]},"reference":[{"issue":"1","key":"2021120900381083300_B1","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1016\/j.cell.2004.09.011","article-title":"Ca(V)1.2 calcium channel dysfunction causes a multisystem disorder including arrhythmia and autism.","volume":"119","author":"Splawski","year":"2004","journal-title":"Cell"},{"key":"2021120900381083300_B2"},{"issue":"1","key":"2021120900381083300_B3","doi-asserted-by":"crossref","first-page":"39","DOI":"10.5435\/00124635-200401000-00006","article-title":"Surgical treatment of congenital syndactyly of the hand.","volume":"12","author":"Dao","year":"2004","journal-title":"J Am Acad Orthop 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