Prenatal diagnosis of Pallister–Killian syndrome in two fetuses with increased nuchal translucency

Prenatal diagnosis of Pallister-Killian syndrome and literature review

Pallister‐Killian syndrome (PKS) is a rare sporadic genetic disorder usually caused by mosaicism of an extra isochromosome of 12p (i(12p)). This retrospective study analysed the prenatal ultrasound manifestations and molecular and cytogenetic results of five PKS foetuses. Samples of amniotic fluid and/or cord blood, skin biopsy and placenta were collected. Conventional karyotyping and single nucleotide polymorphism array (SNP array) were performed on all the amniotic fluid or cord blood samples. Copy number variants sequencing (CNV‐seq) and fluorescence in situ hybridization (FISH) were also used for the validation for one foetus. All the five foetuses were from pregnancies with advanced parental age. Two foetuses involved structural abnormalities and one foetus had only soft markers, all of which included increased nuchal translucency. The rest two foetuses had normal ultrasounds in the second trimester, which has rarely been reported before. The karyotype revealed typical i(12p) in four cases and a small supernumerary marker chromosome consisting of 12p and 20p in the remaining one case. The proportion of cells with i(12p) ranged from 0 to 100% in cultural cells, while SNP array results suggested 2−4 copies of 12p. For one foetus, metaphase FISH showed normal results, but the interphase FISH suggested cell lines with two, three and four copies of 12p in the amniotic fluid. Advanced parental age may be an important risk factor for PKS, and there were no typical ultrasound manifestations related to PKS. A combination of karyotype analysis and molecular diagnosis is an effective method for the diagnosis of PKS.

Prenatal profile of Pallister-Killian syndrome: Retrospective analysis of 114 pregnancies, literature review and approach to prenatal diagnosis

Pallister-Killian syndrome (PKS) is a tissue limited mosaic disorder, characterized by variable degrees of neurodevelopmental delay and intellectual disability, typical craniofacial findings, skin pigmentation anomalies and multiple congenital malformations. The wide phenotypic spectrum of PKS in conjunction with the mosaic distribution of the i(12p) makes PKS an underdiagnosed disorder. Recognition of prenatal findings that should raise a suspicion of PKS is complicated by the fragmentation of data currently available in the literature and challenges in diagnosing a mosaic diagnosis on prenatal testing. Ultrasound anomalies, especially congenital diaphragmatic hernia, congenital heart defects, and rhizomelic limb shortening, have been related to PKS, but they are singularly not specific and are not present in all affected fetuses. We have combined prenatal data from 86 previously published reports and from our cohort of 114 PKS probands (retrospectively reviewed). Summarizing this data we have defined a prenatal growth profile and identified markers of perinatal outcome which collectively provide guidelines for early recognition of the distinctive prenatal profile and consideration of a diagnosis of PKS as well as for management and genetic counseling.

Pallister-Killian syndrome: Review of fetal phenotype

Pallister-Killian syndrome is a multi-system sporadic disorder with developmental delay. It is a rare chromosomal abnormality involving supernumerary isochormosome 12p. The disorder exhibits tissue specific mosaicism. The first prenatal diagnosis of PKS was reported in 1985 after ultrasound detection of fetal anomalies. Since this observation, there have been about 62 reports of fetuses with PKS. In this review, we cover the prenatal aspects of PKS.

[Prenatal and clinicopathological study of 6 cases of Pallister-Killian syndrome and review]

OBJECTIVE

In multidisciplinary prenatal diagnosis centers, the search for a tetrasomy 12p mosaic is requested following the discovery of a diaphragmatic hernia in the antenatal period. Thus, the series of Pallister Killian syndromes (PKS: OMIM 601803) probably overestimate the prevalence of diaphragmatic hernia in this syndrome to the detriment of other morphological abnormalities.

METHODS

A multicenter retrospective study was conducted with search for assistance from members of the French society for Fetal Pathology. For each identified case, we collected all antenatal and postnatal data. Antenatal data were compared with data from the clinicopathological examination to assess the adequacy of sonographic signs of PKS. A review of the literature on antenatal morphological anomalies in case of PKS completed the study.

RESULTS

Ten cases were referred to us: 7 had cytogenetic confirmation and 6 had ultrasound screening. In the prenatal as well as post mortem period, the most common sign is facial dysmorphism (5 cases/6). A malformation of limbs is reported in half of the cases (3 out of 6). Ultrasound examination detected craniofacial dysmorphism in 5 cases out of 6. We found 1 case of left diaphragmatic hernia. Our results are in agreement with the malformation spectrum described in the literature.

CONCLUSION

Some malformation associations could evoke a SPK without classical diaphragmatic hernia.

Pallister-Killian syndrome

PATIENT

Male, 0 FINAL DIAGNOSIS: Pallister-Killian syndrome Symptoms: Decidious tooth • flattened nasal bridge • frontal bossing • grooved palate • low-set ears • mid-facial hypoplasia • nuchal fold thickening • right inquinal testis • shortened upper extremities • undescended left intraabdominal testis • widely spaced nipples

MEDICATION

- Clinical Procedure: - Specialty: Pediatrics and Neonatology.

OBJECTIVE

Congenital defects/diseases.

BACKGROUND

Pallister-Killian syndrome (PKS) is a rare, sporadic, polydysmorphic condition that often has highly distinctive features. The clinical features are highly variable, ranging from mild to severe intellectual disability and birth defects. We here report the first case of PKS diagnosed at our institution in a patient in the second trimester of pregnancy.

CASE REPORT

A pregnant 43-year-old woman presented for genetic counseling secondary to advanced maternal age and an increased risk for Down syndrome. Ultrasound showed increased fetal nuchal fold thickness, short limbs, polyhydramnios, and a small stomach. The ultrasound evaluation was compromised due to the patient's body habitus. The patient subsequently underwent amniocentesis and the karyotype revealed the presence of an isochromosome in the short arm of chromosome 12 consistent with the diagnosis of Pallister-Killian syndrome. Postnatally, the infant showed frontal bossing, a flattened nasal bridge, mid-facial hypoplasia, low-set ears, a right upper deciduous tooth, grooved palate, nuchal fold thickening, widely spaced nipples, left ulnar polydactyly, simian creases, flexion contractures of the right middle finger, shortened upper extremities, undescended left intraabdominal testis, and right inguinal testis.

CONCLUSIONS

The occurrence of PKS is sporadic in nature, but prenatal diagnosis is possible.

Increased nuchal translucency in euploid fetuses--what should we be telling the parents?

Nuchal translucency (NT) measurement between 11 and 14 weeks' gestation is an undisputed marker for aneuploidies. When conventional karyotyping is normal, enlarged NT is a strong marker for adverse pregnancy outcome, associated with miscarriage, intrauterine death, congenital heart defects, and numerous other structural defects and genetic syndromes. The risk of adverse outcome is proportional to the degree of NT enlargement. Although the majority of structural anomalies are amenable to ultrasound detection, unspecified genetic syndromes involving developmental delay may only emerge after birth. Concern over these prenatally undetectable conditions is a heavy burden for parents. However, following detection of enlarged NT the majority of babies with normal detailed ultrasound examination and echocardiography will have an uneventful outcome with no increased risk for developmental delay when compared to the general population. Counseling should emphasize this to help parents restore hope in normal pregnancy outcome and infant development.

Prenatal diagnosis of Pallister-Killian syndrome associated with pulmonary stenosis and right ventricular dilatation

Pallister-Killian syndrome (PKS) is a rare disorder characterized cytogenetically by tetrasomy 12p for isochromosome of the short arm of chromosome 12. PKS is diagnosed by prenatal genetic analysis through chorionic villous sampling, genetic amniocentesis, and cordocentesis, or by chromosomal analysis of skin fibroblasts, but is not usually detected by chromosomal analysis of peripheral blood cells. Herein, we report a case of a gravida at 23 weeks gestation with pulmonary stenosis and right ventricular dilation of the heart which were detected by sonography. Fluorescence in situ hybridization and a multicolor banding technique were performed to verify the diagnosis as 47,XX, +mar.ish i(12)(p10)(TEL++)[16]/46,XX[4], and an autopsy confirmed the cardiac anomalies detected on antenatal sonography.

Tetrasomy 12p (Pallister-Killian syndrome): difficulties in prenatal diagnosis

PURPOSE

We report a rare case of Pallister-Killian syndrome diagnosed prenatally with increased nuchal translucency during screening for trisomy 21.

MATERIALS AND METHODS

Echografic and postmortem examination of the fetus, G-banded chromosome and FISH analysis on short- and long-term chorion villous sampling (CVS) culture.

RESULTS AND DISCUSSION

Cytogenetic analysis revealed a supernumerary isochromosome 12p after long-term culture whereas a normal cell line was detected in short-term culture only. Sonografic examination in 17-weeks' gestation showed further increase of the NT and the additional presence of brachymelia, diaphragmatic hernia and a marked dextroposition of the heart. Termination of the pregnancy was performed. The cases of PKS karyotypically confirmed on CVS are reviewed, and cytogenetic and sonographic aspects of the prenatal diagnosis of PKS are discussed.