Trisomy 22 mosaicism syndrome and Ullrich-Turner stigmata

Trisomy 22 Mosaicism from Prenatal to Postnatal Findings: A Case Series and Systematic Review of the Literature

BACKGROUND

Among aneuploidies compatible with life, trisomy 22 mosaicism is extremely rare, and only about 25 postnatal and 18 prenatal cases have been described in the literature so far. The condition is mainly characterized by facial and body asymmetry, cardiac heart defects, facial dysmorphisms, growth failure, delayed puberty, and variable degrees of neurodevelopmental delay.

PROBLEM

The scattered information regarding the condition and the dearth of data on its natural history and developmental outcomes restrict genetic counseling, particularly in prenatal settings. Moreover, a prompt diagnosis is frequently delayed by the negative selection of trisomic cells in blood, with mosaicism percentage varying among tissues, which often entails the need for further testing. Purpose/topic: The aim of our work is to provide assistance in prenatal and postnatal genetic counseling by systematically delineating the current knowledge of the condition. This entails defining the prenatal and postnatal characteristics of the condition and presenting novel data from three cases, both prenatally and postnatally. Additionally, we report the developmental outcomes observed in two new patients.

Ocular manifestations of mosaic trisomy 22: A case report and review of the literature

Mosaic trisomy 22 is rare, but can be compatible with prolonged life. Patients with mosaic trisomy 22 usually present with intrauterine growth retardation, mental retardation, failure to thrive, and craniofacial asymmetry. We report the case of a five-year-old boy who had a birth weight of 3.8 kg and normal developmental milestones. He presented with unilateral ocular manifestations of ptosis, double elevator palsy, high myopia, and choroidal coloboma involving the macula. Cytogenetic evaluation showed a low level of trisomy 22 in peripheral blood lymphocytes (1 in 100) and in cultured fibroblasts from a conjunctival biopsy of the affected eye (1 in 60). Our case demonstrates the value of chromosomal analysis of the tissues involved rather than just karyotyping of the blood lymphocytes to detect mosaicism in patients with localised and unilateral congenital malformations.

Tetrasomy 13q mosaicism associated with phylloid hypomelanosis and precocious puberty

Various forms of pigmentary dysplasias have been known to be associated with chromosomal mosaicism. One of these disorders, known as phylloid hypomelanosis, has been found to be predominantly associated with abnormalities in chromosome 13. Most of the reported literature involves mosaic trisomy 13 with clinical evidence of abnormal pigmentation in the form of leaf-like or oblong achromic macules following Blaschko's lines. Here, we report on an 8-year-old girl with phylloid hypomelanosis and precocious puberty who was found to have mosaicism for tetrasomy 13q in the form of inverted dup(13)(q21) on her skin fibroblasts as well as peripheral blood karyotype. A higher resolution (244K) chromosomal microarray was done on DNA from skin fibroblasts confirming the breakpoint and gain of distal 13q, which made her tetrasomic for 13q21-qter. This is the first-ever reported association of tetrasomy 13q with phylloid hypomelanosis and precocious puberty. Our report further emphasizes the need to exclude any type of abnormalities of chromosome 13 in patients with phylloid hypopigmentation.

Ultrasound manifestations of unusual trisomies-excluding trisomy 13, 18, and 21: a literature review

Trisomy is the most commonly identified chromosome abnormality, occurring in at least 4% of all clinically recognized pregnancies (1). Most of the trisomies are associated with a single additional chromosome, although 2 other types of trisomic conceptions are occasionally observed, those with 2 additional chromosomes or double trisomy and those with both a normal and trisomic cell line or mosaic trisomies. The adverse effects of trisomy on the phenotype are well established. In this review article, we consider the prevalence of the unusual trisomies (excluding 13, 18, and 21) and present a review of their ultrasound findings.

Abnormal pigmentation in hypomelanosis of Ito and pigmentary mosaicism: the role of pigmentary genes

There is increasing evidence that hypomelanosis of Ito and related disorders such as linear and whorled naevoid hypermelanosis are due to mosaicism for a variety of chromosomal abnormalities. This group of disorders is better termed 'pigmentary mosaicism'. In this review we explain how disparate chromosomal abnormalities might manifest as a common pigmentary phenotype. In particular, we provide evidence supporting the hypothesis that the chromosomal abnormalities reported in these disorders specifically disrupt expression or function of pigmentary genes.

Mosaic trisomy 15 and hemihypertrophy

We report a case of mosaic trisomy 15 with mental retardation, facial dysmorphism, and hemihypertrophy, but no manifestations of Prader-Willi or Angelman syndromes. Mosaic trisomy 15 (11%) was discovered at the amniocentesis. Uniparental disomy for chromosome 15 was excluded by molecular analysis. Post-natal blood karyotype and examination were normal. Mosaic was confirmed on skin fibroblasts, placenta and cord. Evolution was marked by progressive right hemi-hypertrophy, and developmental delay. Our case is the first patient reported with hemihypertrophy associated with mosaic trisomy 15. The relevant literature is reviewed.

Linear hypopigmentation and hyperpigmentation, including mosaicism

Linear streaks of hypopigmentation or hyperpigmentation along Blaschko's lines are currently grouped under the names hypomelanosis of Ito (HI) and linear and whorled hypermelanosis (LWH). Recent studies have suggested that these linear pigmentary anomalies reflect underlying genetic mosaicism. Mosaic individuals are composed of two or more genetically distinct cell populations, a normal and an abnormal population. In HI and LWH, the types of genetic defects that are detectable in the abnormal population are highly variable, including tetraploidy, partial or complete trisomies, translocations, and point mutations. These results, together with recent studies indicating the incidence of extracutaneous anomalies is lower in HI but higher in LWH than previously estimated, have important clinical implications. The need for a revised nomenclature as well as possible modifications in current recommendations for patient management are discussed.

Clinical and molecular studies in full trisomy 22: further delineation of the phenotype and review of the literature

Trisomy 22 is commonly found among spontaneous abortions, second in frequency of occurrence only to trisomy 16. Most earlier reports of surviving trisomy 22 cases in the literature are thought to represent the product of unbalanced 11;22 translocations or the result of undetected mosaicism, since this condition is thought to manifest early embryonic or fetal lethality. We present two strikingly similar cases of non-mosaic trisomy 22 surviving to late gestation. In this paper we emphasize the unique phenotype of this trisomy which included intrauterine growth retardation, microcephaly, broad flat nasal bridge with epicanthal folds and ocular hypertelorism, microtia, variable cleft palate, webbed neck, congenital heart defects involving anomalous great vessels, anorectal and renal anomalies, and hypoplastic distal digits with thumb anomalies. We also explore why some cases survive to late gestation. Confined placental mosaicism, a frequent finding in other lethal trisomies, has been ruled out in one of the cases. Molecular studies done to assess the parental origin of the extra chromosome in the other case showed that the non-disjunction originated during maternal meiosis II. Parental origin of the extra chromosome does not seem to play a role in late survival for trisomy 22.

Melanocytic nevi in Turner syndrome

One morphologic feature of Turner syndrome is increased numbers of melanocytic nevi; however, little attention has been given to their characterization. The development of a melanoma in one of our patients with Turner syndrome prompted this study. We prospectively examined 10 patients with the disease, confirmed by karyotype. All patients underwent full body skin examination noting the number, size, distribution, and degree of clinical atypia of melanocytic nevi. Representative and unusual lesions were photographed. An average of 115 nevi were seen, with the majority measuring 1 to 5 mm. Most were located on the back and extremities. Clinical atypia was uncommon. Our patients had larger numbers of benign-appearing nevi than the general population. Large numbers of melanocytic nevi is a risk factor for melanoma, suggesting that these patients have an increase in one risk factor. Longitudinal studies are indicated to clarify this issue; nevertheless, we recommend periodic skin examinations and the regular use of sunscreens for individuals with Turner syndrome.

Syndromes associated with melanocytic nevi

Melanocytic nevi have been reported in association with several congenital syndromes. This review describes the clinical and cutaneous manifestations of six syndromes associated with congenital melanocytic nevi, two associated with acquired nevi, and six associated with melanocytic nevi in which insufficient evidence exists to classify them as congenital or acquired. It is important to recognize these associations to evaluate and counsel patients with melanocytic nevi. Early recognition will also facilitate timely intervention.

Pigmentary dysplasias and chromosomal mosaicism: report of 9 cases

Chromosomes were studied in 9 individuals with pigmentary dysplasias of the skin and other abnormalities. Of the 9 individuals, 5 were chromosomal mosaics in both blood lymphocytes and skin fibroblasts (46,XY/47,XY, + 13;46,XX/47,XX, + 14;46,XY/47,XY, + 18;46,XX/47,XX, + 18;46, XX/47,XX, + mar), while the other 4 individuals were chromosomally normal in both tissues studied. The pigmentary dysplasias involved hypo- or hyperpigmented patches/flecks or lines/whorls. The latter ran along Blachko lines on the back, abdomen and the limbs. These patterns varied not only between individuals but also between different regions of an individual. The possibility of chimerism was studied but ruled out (1/32 to 1/256) in 7 individuals, using chromosomal heteromorphisms in the patients and their parents as markers.

A clinical study of Noonan syndrome

Clinical details are presented on 151 individuals with Noonan syndrome (83 males and 68 females, mean age 12.6 years). Polyhydramnios complicated 33% of affected pregnancies. The commonest cardiac lesions were pulmonary stenosis (62%), and hypertrophic cardiomyopathy (20%), with a normal echocardiogram present in only 12.5% of all cases. Significant feeding difficulties during infancy were present in 76% of the group. Although the children were short (50% with a height less than 3rd centile), and underweight (43% with a weight less than 3rd centile), the mean head circumference of the group was on the 50th centile. Motor milestone delay was usual, the cohort having a mean age of sitting unsupported of 10 months and walking of 21 months. Abnormal vision (94%) and hearing (40%) were frequent findings, but 89% of the group were attending normal primary or secondary schools. Other associations included undescended testicles (77%), hepatosplenomegaly (50%), and evidence of abnormal bleeding (56%). The mean age at diagnosis of Noonan syndrome in this group was 9.0 years. Earlier diagnosis of this common condition would aid both clinical management and genetic counselling.

Placental mosaicism in a case of 46,XY,-22,+t(22;22)(p11;q11) or i(22q) diagnosed at amniocentesis

46,XY,-22,+t(22;22)(p11;q11) or i(22q) was diagnosed in 15/15 cells from two cultures from the amniotic fluid culture of a 31-year-old patient whose fetus demonstrated cystic hygroma on ultrasound. Cytogenetic studies performed on fetal skin from the abortus revealed the same karyotype as that seen on amniocentesis, but the placenta demonstrated a 46,XY/46,XY,-22,+t(22;22) or i(22q) mosaicism, with 65 per cent of the cells being 46,XY. This case provides an example of placental mosaicism for a normal male karyotype, while the fetus demonstrated non-mosaic trisomy 22.

Trisomy 22 mosaicism limited to skin fibroblasts in a mentally retarded, dysmorphic girl

Less than 10 cases of trisomy 22 mosaicism have been reported. The patients have clinical features in common with both Down's and Turner's syndromes. We report on a 12-year-old girl, in whom the GFR-stimulated gonadotropine response suggested ovarian dysgenesis, although ovarian structures could be demonstrated by ultrasound. The diagnosis of trisomy 22 mosaicism was established by chromosome analysis of cultured skin fibroblasts following a negative lymphocyte culture.

Trisomy 22 in a liveborn infant with multiple congenital anomalies

We report on the third confirmed case of trisomy 22 in a liveborn infant. High-resolution banding studies ruled out translocations such as the relatively common t(11;22). The infant shared many manifestations with other reported cases of trisomy 22 (e.g., growth deficiency, microcephaly, micrognathia, ear malformations, cleft palate, and congenital heart defect) and some manifestations in common with dup 22. Trisomy 22 appears to cause a severe malformation syndrome, and survival to term is rare.

Pigmentary abnormalities and mosaicism for chromosomal aberration: association with clinical features similar to hypomelanosis of Ito

Thirteen patients with hypopigmentation of the skin characteristic of hypomelanosis of Ito, and with developmental disabilities or structural malformations, or both, were examined at our center. Eight were found to have abnormal karyotypes in lymphocytes, fibroblasts, or both. No single clinical feature was predictive of chromosome imbalance in this group of patients. Cytogenetic findings included a balanced de novo X-autosome translocation; ring 10; 45,X/46,X,+ring; mosaic del 13q11 (fibroblasts); mosaic triploidy (fibroblasts); mosaic tetrasomy 12p (fibroblasts); mosaic apparently balanced 15;22 translocation (peripheral blood); and mosaic trisomy 18 (peripheral blood). Hypomelanosis of Ito is characterized by swirly hypopigmentation or depigmentation of the skin with or without other malformations. Autosomal dominant, autosomal recessive, and X-linked dominant inheritance have been suggested but not confirmed. Chromosomal aneuploidy has also been reported. We believe that hypomelanosis of Ito is an etiologically heterogeneous physical finding, and recommend karyotyping of multiple tissues of all patients with abnormal cutaneous pigmentation associated with developmental delay or structural malformations.

Trisomy 22 mosaicism with normal blood chromosomes. Case report with literature review

A female infant with growth failure, microcephaly, hypertelorism, epicanthal folds, preauricular pit, congenital heart defect, hypotonia, and delayed development is reported. Trisomy 22 mosaicism (46,XX/47,XX,+22) was found in cultured skin fibroblasts but not in blood lymphocytes. Trisomy restricted to skin fibroblasts is uncommon.