A child with familial glomerulonephritis: Answers
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CLINICAL QUIZ
A child with familial glomerulonephritis: Answers Marco Pennesi 1
&
Domenica Squillaci 2 & Francesca Diomedi-Camassei 3 & Giulia Pennesi 4 & Egidio Barbi 1,2
Received: 19 March 2020 / Accepted: 23 March 2020 # IPNA 2020
1. Alport syndrome, despite the negative results given by the genetic test, seemed the most likely diagnosis given the patient’s family history and the early onset of the symptoms both in the child and his mother [1]. Alport syndrome should be strongly considered in the event of persistent glomerular hematuria during the first years of life, particularly if the family history presents cases of chronic glomerulonephritis and/or renal failure without other causes or when the characteristic clinical features (hearing loss, lenticonus, or retinopathy) are present [2]. As reported in the latest guidelines by Savige and colleagues [3], the diagnosis is confirmed by the presence of lamellated glomerular basal membrane (GBM) in the examination of the renal biopsy under an electron microscope or by pathogenic mutations detected by genetic testing (one deleterious mutation in the COL4A5 gene, two in the COL4A3 or COL4A4), which has been reported to be at least 90% sensitive for X-linked or automal recessive Alport syndrome. Furthermore, since the mother’s diagnosis of mesangial proliferative glomerulonephritis was obtained by examining renal biopsy tissue, Alport syndrome cannot be excluded as the actual diagnosis, especially if the biopsy examination was conducted without the use of an electron microscope. As a matter of fact, both mesangial proliferative glomerulonephritis (MsPGN) and focal and segmental glomerulosclerosis (FSGS) were shown to be the most This refers to the article that can be found at https://doi.org/10.1007/ s00467-020-04548-w. * Marco Pennesi [email protected] 1
Institute for Maternal and Child Health—IRCCS Burlo Garofolo, Trieste, Italy
2
University of Trieste, Trieste, Italy
3
Bambino Gesù Children’s Hospital, IRCCS, Rome, Italy
4
Edinburgh Napier University, Edinburgh, UK
commonly misdiagnosed glomerulonephritis (26.9% and 19.2% of cases, respectively) [4]. 2. We therefore decided to perform a cutaneous biopsy. Immunofluorescence performed on the skin sample showed the complete absence of the α5-chain of type IV collagen, as typically found in X-linked Alport syndrome patients (Fig. 1). Further genetic analysis performed with multiplex ligation-dependent probe amplification (MLPA) highlighted the presence of a pathogenic duplication of exons 48, 49, and 50 in the COL4A5 gene, therefore confirming X-linked Alport syndrome. Alport syndrome is an inherited disorder of type IV collagen, the major collagenous constituent of basal membranes [5]. The majority of Alport syndrome patients (approximately 85%) present a dominant X-linked hereditary pattern caused by mutations in the COL4A5 gene, found in the Xq22 region, which codes for the α5-chain of type IV collagen [3]. On top of all cases diagnosed by standard genetic testing, there are a few cases (d
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