Dear Colleagues

Patients with intellectual disability, epilepsies and/or hyperphosphatasia (elevated alkaline phosphatase activity in the serum) and/or characteristic facial features a GPI-anchor deficiency should be suspected.

For such cases we offer the molecular diagnostics of all known genes of the GPI-anchor synthesis on a research basis (GPI-gene panel diagnostics). For this analysis we need DNA (>3µg) or EDTA blood (>2ml).

If we cannot find any pathogenic mutations in the known genes we will analyse by flow cytometry whether the expression of GPI-anchored markers is reduced. For this analysis we need either a fibroblast cell culture from a skin biopsy or a fresh blood draw in a Opens external link in current windowCyto Chex tube. In any way you need to inform us before you send the sample as these samples have to be handled with care and the analysis has to be performed in a timely manner.

Skinbiopsies (preferably two) for fibroblast cell cultre have to be send in 10ml cell culture medium (DMEM supplemented with 10% FCS, 1% Glutamine, 1% Penicelline / Sterptomycine).

Please pay attention to the follow points when sending blood samples for flow cytometry analyses:

 • Use the Opens external link in current windowCytoChex BCT tubes for collection of fresh blood.

 • Fill the tube with at least 2ml of fresh blood of the patient.

 • Fill at least 2ml of fresh blood from a healthy individual for travel control.

 • Make sure patient sample and travel control have an equal filling level in the tube.

 • Use express delivery to send the samples within 48 - 72 hours to:


Peter Krawitz, MD

Institute for Medical Genetics, Charité University, Medical School 

Föhrer Str. 15, 13353 Berlin




Please attach the appropriate consent form:

Consent for DNA testing

Consent for flow cytometry

If you already have an NGS data set of an individual with a suspected GPI-anchor deficiency, e.g. a vcf file of an exome, you could also filter the data with the in silico Opens external link in current windowgene panel at Öffnet externen Link im aktuellen FensterGeneTalk.



If we can confirm a GPI-anchor deficiency by flow cytometry we will add the individuals to a cohort with GPI-anchor deficiencies that do not have pathogenic mutations in the known GPI-anchor synthesis genes. We will sequence the exomes, genomes and transcriptomes of the individuals and their parents. We will analyze the sequence data of this cohort to identify new genes that are involved in the GPI-anchor synthesis and maturation.