SALL4 Phenotype in Four Generations of One Family: An Interplay of the Upper Limb, Kidneys, and the Pituitary

INTRODUCTION

The SALL4 gene encodes a transcription factor that is essential for early embryonic cellular differentiation of the epiblast and primitive endoderm. It is required for the development of neural tissue, kidney, heart, and limbs. Pathogenic SALL4 variants cause Duane-radial ray syndrome (Okihiro syndrome), acro-renal-ocular syndrome, and Holt-Oram syndrome. We report a family with vertical transmission of a SALL4 pathogenic variant leading to radial hypoplasia and kidney dystopia in several generations with additional growth hormone deficiency (GHD) in the proband.

CASE PRESENTATION

Our male proband was born at the 39th week of gestation. He was born small for gestational age (SGA; birth weight 2,550 g, -2.2 SDS; length 47 cm, -2.0 SDS). He had bilateral asymmetrical radial ray malformation (consisting of radial hypoplasia, ulnar flexure, and bilateral aplasia of the thumb) and pelvic kidney dystopia, but no cardiac malformations, clubfoot, ocular coloboma, or Duane anomaly. He was examined for progressive short stature at the age of 3.9 years, where his IGF-1 was 68 μg/L (-1.0 SD), and growth hormone (GH) after stimulation 6.2 μg/L. Other pituitary hormones were normal. A brain CT revealed normal morphology of the cerebral midline and the pituitary. He had a dental anomaly - a central mandibular ectopic canine. MRI could not be done due to the presence of metal after multiple corrective plastic surgeries of his hands. His mother's and father's heights are 152.3 cm (-2.4 SD) and 177.8 cm (-0.4 SD), respectively. His father has a milder malformation of the forearm. The affected paternal grandfather (height 164 cm; -2.3 SD) has a radial ray defect with missing opposition of the thumb. The family reports a similar phenotype of radial dysplasia in the paternal grandfather's mother. The proband started GH therapy at age 6.5 years when his height was 109 cm (-2.8 SDS) and he experienced catch-up growth as expected in GHD. Puberty started spontaneously at the age of 12.5 years. At age 13, his height was 158.7 cm (-0.2 SDS). Whole-exome sequencing revealed a nonsense variant in the SALL4 gene c.1717C>T (p.Arg573Ter) in the proband, his father, and paternal grandfather.

CONCLUSION

This is the first observation of a patient with a congenital upper limb defect due to a pathogenic SALL4 variant who has isolated GHD with no apparent cerebral or facial midline anomaly and has been successfully treated with growth hormone.

Integrative Role of the SALL4 Gene: From Thalidomide Embryopathy to Genetic Defects of the Upper Limb, Internal Organs, Cerebral Midline, and Pituitary

BACKGROUND

The thalidomide disaster resulted in tremendous congenital malformations in more than 10,000 children in the late 1950s and early 1960s.

SUMMARY

Although numerous putative mechanisms were proposed to explain thalidomide teratogenicity, it was confirmed only recently that thalidomide, rather its derivative 5-hydroxythalidomide (5HT) in a complex with the cereblon protein, interferes with early embryonic transcriptional regulation. 5HT induces selective degradation of SALL4, a principal transcriptional factor of early embryogenesis. Genetic syndromes caused by pathogenic variants of the SALL4 gene phenocopy thalidomide embryopathy with congenital malformations ranging from phocomelia, reduced radial ray, to defects of the heart, kidneys, ear, eye, and possibly cerebral midline and pituitary. SALL4 interacts with TBX5 and a handful of other transcriptional regulators and downregulates the Sonic hedgehog signaling pathway. Cranial midline defects, microcephaly, and short stature due to growth hormone deficiency have been occasionally reported in children carrying SALL4 pathogenic variants associated with generalized stunting of growth rather than just the loss of height attributable to the shortening of leg bones in many children with thalidomide embryopathy.

KEY MESSAGES

Thus, SALL4 joins the candidate gene list for monogenic syndromic pituitary insufficiency. In this review, we summarize the journey from the thalidomide disaster through the functions of the SALL4 gene to its link to the hormonal regulation of growth.

Two New Mutations in the CEL Gene Causing Diabetes and Hereditary Pancreatitis: How to Correctly Identify MODY8 Cases

CONTEXT

Maturity onset diabetes of the young, type 8 (MODY8) is associated with mutations in the CEL gene, which encodes the digestive enzyme carboxyl ester lipase. Several diabetes cases and families have in recent years been attributed to mutations in CEL without any functional or clinical evidence provided.

OBJECTIVE

To facilitate correct MODY8 diagnostics, we screened 2 cohorts of diabetes patients and delineated the phenotype.

METHODS

Young, lean Swedish and Finnish patients with a diagnosis of type 2 diabetes (352 cases, 406 controls) were screened for mutations in the CEL gene. We also screened 58 Czech MODY cases who had tested negative for common MODY genes. For CEL mutation-positive subjects, family history was recorded, and clinical investigations and pancreatic imaging performed.

RESULTS

Two cases (1 Swedish and 1 Czech) with germline mutation in CEL were identified. Clinical and radiological investigations of these 2 probands and their families revealed dominantly inherited insulin-dependent diabetes, pancreatic exocrine dysfunction, and atrophic pancreas with lipomatosis and cysts. Notably, hereditary pancreatitis was the predominant phenotype in 1 pedigree. Both families carried single-base pair deletions in the proximal part of the CEL variable number of tandem repeat (VNTR) region in exon 11. The mutations are predicted to lead to aberrant protein tails that make the CEL protein susceptible to aggregation.

CONCLUSION

The diagnosis of MODY8 requires a pancreatic exocrine phenotype and a deletion in the CEL VNTR in addition to dominantly inherited diabetes. CEL screening may be warranted also in families with hereditary pancreatitis of unknown genetic etiology.

Short stature in a boy with atypical progeria syndrome due to LMNA c.433G>A [p.(Glu145Lys)]: apparent growth hormone deficiency but poor response to growth hormone therapy

Background Hutchinson-Gilford progeria syndrome (HGPS) is a rare disease caused by pathogenic variants in the LMNA gene, which leads to premature aging. The median life expectancy is shortened to 13 years due to cardiovascular complications. Case report We present a boy born with a pathogenic LMNA variant c.433G > A, which causes atypical progeria syndrome (APS) and was previously described in one single patient. When investigated for poor growth prior to the diagnosis of APS, his laboratory tests revealed growth hormone (GH) deficiency and magnetic resonance imaging (MRI) of the midbrain showed partial empty sella. GH treatment had only a limited and transient effect. His first ischemic complication manifested at age 4.2 years; at the age of 7 years, he had a fatal haemorrhagic stroke. Conclusion To the best of our knowledge, this is the first patient with APS showing partial empty sella and GH deficiency that might have contributed to his poor growth. GH failed to improve long-term outcome.

[Liver, kidneys and diabetes: three faces of HNF1B gene deficit]

The renal cysts and diabetes syndrome (RCAD), also known as HNF1B-MODYor MODY5, is caused by the deletion or point mutation of HNF1B gene which leads to the depletion of HNF1B transcription factor. The main clinical components of RCAD include cystic kidney disease or other developmental anomalies of the kidneys and diabetes mellitus which typically manifests in the second decade of life or later. Renal disorders may lead to the development of chronic renal insufficiency already in childhood or young adulthood. The other symptoms include hepatic impairment - cholestatic jaundice in middle-aged patients, sometimes even neonatal cholestasis, atrophy of the pancreas with the impairment of exocrine pancreatic secretion and some congenital anomalies of the genital tract. As opposed to the other forms of MODY diabetes, the family history may not be positive because most of the deviations of HNF1B appear de novo. We associate RCAD in particular with adults suffering from diabetes and cystic kidney disease and/or cholestatic jaundice and children with cystic kidney disease of unclear etiology, even without the presence of diabetes. A supportive finding may be hypomagnesemia which occurs in up to 70 % of patients diagnosed with HNF1B related disease and hyperuricemia.Key words: HNF1B - MODY - RCAD - diabetes mellitus - cholestatic jaundice.