First trimester diagnosis of Gaucher disease in a fetus with trisomy 21

Congenital Ichthyosis: Current Approaches to Prenatal Diagnoses

INTRODUCTION

Congenital ichthyosis represents a wide spectrum of diseases. This article reviews prenatal testing for ichthyosis.

METHODS

We used pubmed.ncbi.nlm.nih.gov to search for 38 types of congenital ichthyosis combined with 17 words related to prenatal testing.

RESULTS

Search resulted in 408 publications covering 13 types of ichthyoses and four types of tests.

DISCUSSION

Biochemical testing is diagnostic in trichothiodystrophy, but nonspecific in X-linked ichthyosis and Refsum syndrome. Except in X-linked ichthyosis, biochemical testing requires invasive procedures to obtain fetal skin biopsy, amniocytes, or chorionic villus samples. It is superior to histological and cytological examination of fetal skin biopsy or amniocytes because keratinization occurs later in pregnancy and microscopy cannot differentiate between ichthyosis types. Imaging is more acceptable due to noninvasiveness and routine use, although ultrasonography is operator-dependent, nonspecific, and captures abnormalities at late stage. Molecular tests are described in at-risk pregnancies but testing of free fetal DNA was not described.

Dual diagnosis of trisomy 21 and lethal perinatal Gaucher disease as a cause of non-immune hydrops fetalis in a twin pregnancy for a consanguineous couple

Non-immune hydrops is a prenatal finding which can occur due to an underlying genetic diagnosis such as common chromosomal aneuploidy (Trisomy 21, Turner syndrome etc.). It is extremely rare to have more than one genetic cause of hydrops fetalis in a single pregnancy. This report describes a dichorionic diamniotic pregnancy for a consanguineous couple where noninvasive prenatal testing was "high risk" for Trisomy 21. Family declined amniocentesis and opted for postnatal genetic testing. The pregnancy was later complicated with severe hydrops fetalis leading to demise for one of the twins, and a premature delivery of the other twin who had remarkable collodion not in keeping with Trisomy 21. Postnatal genetic investigations confirmed both Trisomy 21 and prenatal lethal Gaucher disease in the survivor twin. This case report highlights some of the prenatal diagnostic challenges for a consanguineous couple where a rare cause of fetal hydrops was concealed in a setting of a common chromosomal aneuploidy. The prompt postnatal diagnosis of perinatal lethal Gaucher disease, confirmed with undetectable glucocerebrosidase enzyme activity, assisted the family in the decision of providing palliative care for their infant who was quickly deteriorating. The importance of postnatal genetic evaluation and its impact on immediate patient management in an NICU setting is emphasized. This dual diagnosis was significant for the couple as it explained pervious pregnancy losses and has important future recurrence risk implications.

Gaucher's disease: genetic counselling and population screening

Genetic counselling for Gaucher's disease requires a comprehensive approach, including accurate diagnosis at both the enzymatic and molecular levels, and assessment of disease severity. These goals are particularly challenging given the great allelic and phenotypic heterogeneity encountered in this disorder. Counselling should address the specific concerns of the counsellee, which may be related to evaluation of an affected person, or to reproductive options in couples at risk. Advances in both diagnosis and treatment have led to increased ascertainment of cases and carriers through population based screening, rather than through affected probands, raising new ethical and medical dilemmas. This chapter outlines practical issues in counselling for the various forms of Gaucher's disease, based on current data and experience.