Smith-Lemli-Opitz syndrome – detection of the 3 most common mutations in the DHCR7 gene (p.Trp151Ter, p.Val326Leu and c.964-1G>C)

Test covered by the reimbursement:

YES

Gender:

Woman

Material:

Chorionic villi, Amniotic fluid …

Turnover time:

3 weeks

STATIM:

1 week

Material:

Chorionic villi | Chorionic villi, min. 30 mg tissue in a microtube (Eppendorf type)

Storage before examination: 1 day 15–25°C, 2–8°C for >8 hrs after collection

Amniotic fluid | 3x 10 ml of amniotic fluid in a tube

Storage before examination: 1 day 15–25°C, 2–8°C for >8 hrs after collection

Cord blood | 2–3 ml of cord blood in EDTA

Storage before examination: 1 days 15–25°C, 2–8°C for >8 hrs after collection

Isolated DNA from chorionic villi | 30–100 ng/μL of isolated DNA from chorionic villi in a microtube (Eppendorf type)

Storage before examination: 5 days 15 – 25°C

Isolated DNA from amniotic fluid | 30–100 ng/μL of isolated DNA from amniocentesis in a microtube (Eppendorf type)

Storage before examination: 5 days 15 – 25°C

Isolated DNA from cordocentesis | 30–100 ng/μL of isolated DNA from cordocentesis in a microtube (Eppendorf type)

Storage before examination: 5 days 15 – 25°C

DNA isolated from cultured cells | 30–100 ng/μL of isolated DNA from cultured cells in a microtube (Eppendorf type)

Storage before examination: 3 days 15 – 25°C

Quick test description:

Screening of the 3 most common DHCR7 gene mutations: c.452G>A (p.Trp151Ter), c.976G>T (p.Val326Leu), c.964-1G>C (IVS8-1G>C) using Sanger sequencing, which represent about 81% of all mutations in patients with SLOS (Smith-Lemli-Opitz syndrome, OMIM 270400).

Test details:

The DHCR7 gene encodes the enzyme 7-dehydrocholesterol reductase. This enzyme is responsible for the final step in cholesterol production. Mutations in the DHCR7 gene therefore lead to decreased cholesterol and elevated cholesterol precursors leading to Smith–Lemli–Opitz syndrome (SLOS). The accumulation of this cholesterol precursor is embryotoxic and can lead to intrauterine foetal death. The spectrum of malformations in SLOS is quite diverse, e.g. microcephaly, cleft palate, 2/3 finger syndactyly, polydactyly, facial malformations, heart and kidney anomalies, ambiguously differentiated genitalia in boys. Clinical manifestations are highly variable from moderate dysmorphism with mild mental retardation (SLO I) to intrauterine death or death at an early age of the foetus with SLO syndrome (SLO II). SLOS with fully manifested symptoms is estimated to be the cause of some spontaneous abortions. It is the only disease that is treated by administering cholesterol. Sanger sequencing is used to detect the 3 most common mutations in the DHCR7 gene: c.452G>A (p.Trp151Ter), c.976G>T (p.Val326Leu) and c.964-1G>C (IVS8-1G>C).

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