Pallister-Hall syndrome associated with an unbalanced chromosome translocation

7q Deletion/12q Duplication Is the Possible Cause of an Alobar Holoprosencephaly Case

Holoprosencephaly (HPE) spectrum disorder is the most common congenital malformation of the human brain with absence of or incomplete midline cleavage. Its cause is heterogenic, making genetic counseling a challenge. In this case report, a pregnancy affected by alobar HPE is described. Using aCGH, an 8.9-Mb deletion at 7q36.1q36.3 together with a 4.9-Mb duplication at 12q24.32q24.33 is assumed to be the possible reason for this alobar HPE case. It is discussed that disruption of key elements of the developing brain, taking environmental factors into account, contributes to the HPE spectrum. The use of aCGH for invasive prenatal testing is starting to become the standard technique, providing accurate information about the cause of congenital diseases for couples receiving genetic counseling.

Distal 3p duplication and terminal 7q deletion associated with nuchal edema and cyclopia in a fetus and a review of the literature

OBJECTIVE

To present perinatal detection of distal 3p duplication and terminal 7q deletion associated with nuchal edema and cyclopia in a fetus, and to review the literature.

MATERIALS AND METHODS

A 32-year-old, G9P0, woman who had experienced eight spontaneous abortions was found to have fetal nuchal edema, alobar holoprosencephaly, and cyclopia by prenatal ultrasound at 15 weeks of gestation. The pregnancy was subsequently terminated, and a malformed fetus was delivered with cyclopia. Molecular and conventional cytogenetic analyses were made to determine the genetic pathogenesis of fetal abnormalities.

RESULTS

The father had a karyotype of 46,XY,t(3;7)(p22.1;q36.1). The mother had a karyotype of 46,XX. The fetus had a karyotype of 46,XY,der(7)t(3;7)(p22.1;q36.1)pat. The analysis of array comparative genomic hybridization analysis revealed a 43.68-Mb duplication of 3p26.3-3p22.1 encompassing CHL1 and CNTN4, and an 8.66-Mb deletion of 7q36.1-7q36.3 encompassing SHH in the fetus.

CONCLUSION

Simultaneous occurrence of 7q deletion and 3p duplication can be associated with alobar holoprosencephaly. For the couple with a parental translocation involving 7q and 3p, prenatal ultrasound should include a detailed investigation of central nervous system anomalies.

Sonic Hedgehog deletion and distal trisomy 3p in a patient with microphthalmia and microcephaly, lacking cerebral anomalies typical of holoprosencephaly

About 20% of cases with 7q deletion syndrome is associated with holoprosencephaly (HPE), due to deletion of the Sonic Hedgehog (SHH) gene (mapping to 7q36). The occurrence of severe forms of holoprosencephaly is higher in cases of 7q deletion associated with partial trisomies involving different parts of the genomes than in patients with pure 7q deletion. All cases of 7q deletion associated with 3p duplication reported to date have been associated with severe forms of holoprosencephaly, and a gene(s) on distal 3p has (have) been hypothesized to be responsible for HPE phenotype when in triple dose. Here we describe a patient with unbalanced 3p;7q translocation, showing 7q deletion (including SHH gene) and 3p duplication (complete karyotype was 46,XY,der(7)t(3;7)(p26.3;q36.1)), presenting with a relatively mild phenotype, consisting of microphthalmia and microcephaly, without cerebral anomalies typical of holoprosencephaly. Possible involvement of some genes on 3p in determining such a mild phenotype is discussed.

Reassessment of holoprosencephaly–diencephalic hamartoblastoma (HDH) association

We report on a 23-week fetus with a hypothalamic hamartoma, lobar holoprosencephaly, right anophthalmia, and facial asymmetry, features which are consistent with the holoprosencephaly-diencephalic hamartoblastoma (HDH) association. In an attempt to better delineate HDH, we reviewed 19 published patients with similar features. The HDH clinical spectrum ranges from classic holoprosencephaly with micro/anophthalmia, multiple additional findings in non-contiguous structures and early lethality, to isolated microforms of holoprosencephaly. Associated cephalic features mainly include cortical/neuronal migration defects (39%), meningeal anomalies (28%), brainstem/posterior fossa malformations (22%), dysmorphic ears (41%), facial asymmetry (35%), and hypoplastic mandible (29%). Fifty-three percent of patients have additional extra-cephalic malformations, for example, vertebral/rib segmentation defects (50%), hypo/aplastic lungs (38%), congenital heart defect (29%), and urinary anomalies (29%). HDH shows etiological heterogeneity, that is, teratogenic exposure, chromosome imbalances, autosomal recessive as well as dominant "de novo" mutations. Several features could directly result from a disruptive sequence caused by an early hamartoma which alters the development of forebrain, hindbrain, meninges, and 1st-2nd branchial arches, although the pleiotropic action of genetic/environmental factors cannot be excluded. HDH does not emerge as a distinct syndrome, but other hypotheses, including separate conditions within a common pathway and the developmental field defect theory, are discussed.

Psychiatric and neuropsychological characterization of Pallister-Hall syndrome

Pallister-Hall syndrome (PHS) is a rare, single-gene, malformation syndrome that includes central polydactyly, hypothalamic hamartoma, bifid epiglottis, endocrine dysfunction, and other anomalies. The syndrome has variable clinical manifestations and is inherited in an autosomal dominant pattern. We sought to determine whether psychiatric disorders and/or neuropsychological impairment were characteristic of PHS. We prospectively conducted systematic neuropsychiatric evaluations with 19 PHS subjects ranging in age from 7 to 75 years. The evaluation included detailed clinical interviews, clinician-rated and self-report instruments, and a battery of neuropsychological tests. Seven of 14 adult PHS subjects met diagnostic criteria for at least one DSM-IV Axis I disorder. Three additional subjects demonstrated developmental delays and/or neuropsychological deficits on formal neuropsychological testing. However, we found no characteristic psychiatric phenotype associated with PHS, and the frequency of each of the diagnoses observed in these subjects was not different from that expected in this size sample. The overall frequency of psychiatric findings among all patients with PHS cannot be compared to point prevalence estimates of psychiatric disease in the general population because of biased ascertainment. This limitation is inherent to the study of behavioral phenotypes in rare disorders. The general issue of psychiatric evaluation of rare genetic syndromes is discussed in light of this negative result.

Long-term treatment with growth hormone improves final height in a patient with Pallister-Hall syndrome

Pallister-Hall syndrome is a disorder of development consisting of hypothalamic hamartoma, pituitary dysfunction, central polydactyly and visceral malformations. This disorder is inherited as an autosomal dominant trait and is caused by mutations of the GLI3 gene encoding a zinc finger transcription factor. We describe a case of Pallister-Hall syndrome with growth hormone neurosecretory dysfunction, successfully treated with growth hormone until attainment of final height. We conclude that children with Pallister-Hall syndrome and short stature be evaluated carefully for spontaneous somatotropic function and, if necessary, treated with growth hormone.

Hypothalamic dysfunction with polydactyly and hypoplastic nails

Attention to a careful diagnostic work-up should be given to patients with postaxial polydactyly or apparently isolated hypothalamic hamartomas. Early recognition of the condition is critical for management, particularly for anticipating and preventing endocrine emergencies. Conservative management of the hypothalamic hamartoma should be stressed. Finally, detailed genetic counseling should be provided to the family regarding autosomal-dominant inheritance as well as the wide range of interfamilial and intrafamilial variability.

Autosomal dominant inheritance of hypothalamic hamartoma associated with polysyndactyly: heterogeneity or variable expressivity?

We report on a two-generation family exhibiting dominant inheritance of complex polysyndactyly associated with hypothalamic hamartoma. These individuals have some manifestations of Pallister-Hall syndrome (PHS), but their phenotype is milder. The proposita is a 16-year-old girl with polysyndactyly of the hands and feet, short stature, and a large hypothalamic hamartoma. Her brother and father also have polysyndactyly and a hypothalamic mass on MRI scan. All three have normal appearance and intelligence, with normal pituitary function. Several other paternal relatives have polysyndactyly as well. We propose that this family may represent a clinically and perhaps genetically distinct entity from PHS, based on normal survival, normal intelligence, lack of endocrine dysfunction or facial anomalies, and few other structural malformations. Linkage analysis is in progress to determine whether this represents a benign form of PHS or a genetically separate condition. The phenotypic differences between these cases and classic PHS have important prognostic and recurrence risk implications.

Exclusion of candidate loci and cholesterol biosynthetic abnormalities in familial Pallister-Hall syndrome

Pallister-Hall syndrome (PHS) was originally described in 1980 in six sporadic cases of children with structural anomalies including hypothalamic hamartoma, polydactyly, imperforate anus, and renal and pulmonary anomalies. In 1993, the first familial cases were reported, including affected sibs and vertical transmission. Three of these families are sufficiently large to allow initial evaluation by linkage studies to candidate genes or loci. We have evaluated candidate loci for PHS based on three clinical observations. The first is a patient with PHS-like malformations, including a hypothalamic hamartoma, and an unbalanced translocation involving 7q and 3p. The second is a family with familial PHS where the founder's father had an autosomal dominant hand malformation previously mapped to 17q. The third is the phenotypic overlap of PHS and Smith-Lemli-Opitz syndrome. In this report, we exclude these loci as candidates for linkage to the PHS phenotype on the basis of lod scores of less than-2.0. We conclude that hypothalamic hamartoma is not specific to PHS and that the dominant hand malformation in one of the families was a coincidence. To evaluate the relationship of PHS to Smith-Lemli-Opitz syndrome, we analysed levels of cholesterol and intermediate metabolites of the later stages of cholesterol biosynthesis. There is no evidence of a generalised disorder of cholesterol biosynthesis in patients with familial PHS. On genetic and biochemical grounds, we conclude that PHS and Smith-Lemli-Opitz syndrome are not allelic variants of a single locus.

Prenatal diagnosis of terminal deletion 7q and partial trisomy 3p in fetuses with holoprosencephaly

Chromosome aberrations, mendelian mutations and exogenous agents can cause holoprosencephaly. Therefore, etiologic evaluation of holoprosencephaly is necessary for obstetricians and genetic counselors, once a prenatal diagnosis of holoprosencephaly has been made. We present four pregnancies in three women in which routine sonographic examinations led to the prenatal diagnosis of holoprosencephaly. Prenatal cytogenetic analysis and fluorescence in situ hybridization demonstrated a 46,XY,del(7)(pter-->q32:) and a 46,XY,der(2)t(2;3)(q37;p21)pat karyotype respectively in two fetuses with cyclopia, and a 46,XX,der(2)t(2;3)(q37;p21)pat and a 46,XX,der(7)t(3;7)(p23;q36) karyotype respectively in two fetuses with premaxillary agenesis. In conclusion, terminal deletion 7q and partial trisomy 3p in holoprosencephalic fetuses indicates that genes contributing to craniofacial development reside in these critical regions. Proper prognostic evaluation in further pregnancies requires expertise in cytogenetics and genetic counseling.

Pallister-Hall syndrome

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Imperforate anus, bilateral hydronephrosis, bilateral undescended testes and pituitary hypoplasia: a variant of Hall-Pallister syndrome or a new syndrome

A patient with multiple congenital malformations, including imperforate anus, bilateral cryptorchidism and microphallus, is described. At 4 months of age the infant had generalized convulsions and hypoglycaemia. Bilateral hydronephrosis was diagnosed at 8 months of age. At 10 months he was diagnosed as having panhypopituitarism secondary to anterior pituitary hypoplasia, shown on CT and MRI scans. This clinical picture partially resembles that of Hall-Pallister syndrome. However, the absence of some typical features such as craniofacial and limb abnormalities and, above all, hypothalamic hamartoblastoma, would also suggest the possibility of a new, previously unreported, syndrome.

Polysyndactyly and asymptomatic hypothalamic hamartoma in mother and son: a variant of Pallister-Hall syndrome

We report on a 53-year-old woman and her 20-year-old son who both presented with polysndactyly, without other external malformations or mental retardation. MRI imaging revealed, as an incidental finding, asymptomatic hypothalamic hamartomas in both patients. The siblings of both mother and son are unaffected. This family may represent an autosomal dominant variant of Pallister-Hall syndrome.

Stringent delineation of Pallister-Hall syndrome in two long surviving patients: importance of radiological anomalies of the hands

We report two unrelated, long surviving patients (2 and 17 years) with syndromal hypothalamic hamartoblastoma. Both showed mild facial dysmorphism (downward slanted palpebral fissures, ptosis, microretrognathia), cleft epiglottis, and developmental delay. The younger child had stenosis of the pulmonary arteries, complex urogenital malformations, and anal atresia. In the oldest patient, the hamartoma caused precocious puberty of the central type, combined with complete hGH deficiency. Both patients showed bony anomalies of the extremities: variable proximal synostosis between central (2nd to 4th) metacarpals or intercalary polydactyly with generalised brachydactyly, severe brachytelephalangism, syndactyly, and nail hypoplasia. Together with the absence of anomalies of cholesterol metabolism, a combination of oral frenula, laryngeal malformations, digestive abnormalities, intercalary polysyndactyly, generalised brachytelephalangism, and nail hypoplasia should allow the delineation of Pallister-Hall syndrome, even when a CNS tumour is absent. The radiological abnormalities are helpful in differentiating Pallister-Hall syndrome from the other syndromes in which hypothalamic hamartoblastoma is observed. This is of major importance for genetic counselling, since Pallister-Hall syndrome may be a dominantly inherited disorder, thus contrasting with most of the other disorders with the CAVE phenotype, which are recessively inherited.

Autosomal dominant transmission of the Pallister-Hall syndrome

We describe a 9-year-old boy and his 34-year-old father with the Pallister-Hall syndrome. The proband had precocious puberty, imperforate anus, postaxial polydactyly, hypospadias, a hypothalamic mass, and a displaced pituitary gland. The father had polydactyly, a hypothalamic mass, and a flattened pituitary gland. We conclude that the most likely cause of the Pallister-Hall syndrome is a mutation in a gene inherited in an autosomal dominant manner.

Familial Pallister-Hall syndrome: case report and hormonal evaluation

Pallister-Hall syndrome is a usually lethal dysplasia/malformation syndrome characterized by hypothalamic hamartoblastoma, hypopituitarism, postaxial polydactyly, craniofacial malformations, imperforate anus, and other malformations. We report a familial case in a male infant and his female sib fetus, suggesting autosomal recessive inheritance, or germinal mosaicism for an autosomal dominant mutation, or a segregating submicroscopic chromosome abnormality. Detailed endocrine evaluation on the surviving infant revealed documented pituitary function, pituitary deficit, and hypothalamic deficiency. We suggest that hypothalamic dysfunction contributes to the hypopituitarism seen in Pallister-Hall syndrome.

Autosomal imbalance syndromes: genetic interactions and the origin of congenital malformations in aneuploidy syndromes

In some autosomal imbalance syndromes an additional imbalance interferes with the occurrence of the anomalies typical of the syndrome itself. For example, polydactyly was found in patients with "pure" del(3p) more frequently (11/23) than in patients where these deletions were associated with different partial trisomies (2/28). The opposite situation was shown in del(7q) syndrome where various defects of the holoprosencephalic group were found to be rarer in patients with "pure" deletions, than in cases with simultaneous occurrence of various partial trisomies. It suggests the importance of gene interaction in determining the phenotypic picture of autosomal imbalance syndromes.