2nd IPNA ESPN MASTER for

JUNIOR CLASSES

CYSTINOSIS

Prof.Dr. Rezan Topaloglu Hacettepe University Faculty of Medicine

Department of Pediatric Nephrology Ankara Turkey

R.Topaloglu

Cystinosis Rare autosomal recessive disorder estimated incidence

1/ 100.000 live births

Lysosomal storage disease

Types Classical, Infantile, Nephropathic cystinosis

Late onset cystinosis Juvenile or Intermediate form

Ocular non nephropatic form Adult or Bening form

R.Topaloglu

Clinical Findings of Nephropatic Cystinosis According to Age

Age Presentation

Birth Normal

Infancy Renal Tubular Fanconi syndrome

-Dehydration, polyuria, polydipsia

-Metabolic acidosis

-Hypokalemi

-Hypophosphatemic rickets

-Hypocalcemic tetany

Growth retardation Vomiting

Early childhood Photophobia

Pre-adolescence Renal failure

Renal osteodystrophy

Hypothyroidism

Pediatr Nephrol 2008;28:863 R.Topaloglu

Late onset cystinosis Juvenile or Intermediate form

Onset at a later age. Often does not presents with Fanconi syndrome Renal failure occurs usually between ages 15-25 years

Presents with photophobia, crystals form in cornea

Ocular- Non nephropathic form or Bening form

R.Topaloglu

Metabolic defect

Autosomal recessive disorder characterized by

intra lysosomal accumulation of cystine due to

a defect in the lysosomal transport of cystine

Lysosomal transporter-CYSTINOSIN

coded by CTNS gene

R.Topaloglu

KI 2012: 81;127-129

R.Topaloglu

LOCALIZATION &

IDENTICATION OF CTNS GENE

R.Topaloglu

1. Letter

Nature Genetics 10, 246 - 248 (1995) doi:10.1038/ng0695-246

Linkage of the gene for cystinosis to markers on the short arm of

chromosome 17

The Cystinosis Collaborative Research Group

Geraldine A. McDowell1, ,8, William A. Gahl1, ,8, Leah A. Stephenson1, ,8, Jerry A.

Schneider2, ,8, Jean Weissenbach3, ,8, Mihael H. Polymeropoulos4, ,8, Margaret M.

Town5, ,9, William van't Hoff6, ,9, Martin Farrall7, ,9 & Christopher G. Mathew5, ,9

Cystinosis gene located on Chromosome 17 short arm p13.3

linkage of the cystinosis gene to markers on the short arm of chromosome 17

(Zmax=10.89, =0.03) for marker D17S1584. Multipoint analysis and haplotypes

in recombinant families suggest that the gene is located between markers

D17S1583 and D17S796 -4cM interval

D17S1798 D17S1828 1 cM

2. Am J Hum Genet 1996; 58:535-543 Jean G et al

Reduced the interval to 1 cM

R.Topaloglu

• In 1998, a large deletion was detected in the homozygous state in over a third of affected european individuals.

• a 13 kb deletion in a single family, • searching for the causative gene to the region of overlap. • novel gene is identified by using a positional cloning strategy in this

region • the various mutations were detected within its coding region in

affected individuals validated it as the gene responsible for cystinosis

• It is named as CTNS gene

R.Topaloglu

CTNS gene

structure

2

Cytoplasm

Lysosomal membrane

Lysosome

N-terminus

C-terminus

GY-DQ-L CTNS product Cystinosin predicted structure

367 aa

YFPQA

R.Topaloglu

Mutations in CTNS gene

More than 110 mutations have been reported

Big deletion 57 kb

Small deletions (13kb, 4 kb deletions)

Insertions

Missense or nonsense mutations

Splicing mutations

Partial replication of exon 9, a skipping of exon 5 (85 bp)

R.Topaloglu

•The size of this deletion was determined to be 57 kb Am J Hum Genet 1998;63:1352-

1362

•57kb deletion that covers the first 9 exons and introns and intrups exon 10

•57 kb deletion extends into CARKL and TRPV1 gene causing more complex

phenotypes

•76 % of patients European origin have this deletion either in heterozygous or

homozygous state

•In the US and Northren European populations 50 % of individuals with nephropathic

cystinosis is homozygous for this deletion

57 Kb deletion

Clinical Findings of Nephropatic Cystinosis According to Age

Age Presentation

Birth Normal

Infancy Renal Tubular Fanconi syndrome

-Dehydration, polyuria, polydipsia

-Metabolic acidosis

-Hypokalemi

-Hypophosphatemic rickets

-Hypocalcemic tetany

Growth retardation

Vomiting

Early childhood Photophobia

Pre-adolescence Renal failure

Renal osteodystrophy

Hypothyroidism

Pediatr Nephrol 2008;28:863 R.Topaloglu

Diagnosis confirmation

The diagnosis can be confirmed by

measurement of leukocyte cystine levels

demonstration of corneal cystine crystals by the slit lamp exam and

genetic analysis of the CTNS gene.

R.Topaloglu

Renal Disease

Main Predictor of prognosis

R.Topaloglu

Renal Disease Characteristics

Proximal RTA

Renal loss of Na and K - Hyponatremia & Hypokalemia

Hyperuricosuria-Hypourecemia

Carnitinuria- Decrease plasma carnitine

hypercalciuria & hyperphosphaturia- Medullary nephrocalsinosis

Increased protein excretion

albuminuria

LMW proteinuria- Vit D binding protein, α1 microglobulin, β2 microglobulin, RBP

High molecular weight prt-IgG

R.Topaloglu

Renal disease Characteristics

Generalized aa uria 10 times normal values

Urinary cystine concentration is elevated

No cystine stones Why ?

Diluted urine

Alkaline Urine

In late childhood medullary nephrocalsinosis due to hypercalsiuria and hyperhosphaturia

N Eng J Med 2002; 347:111-121 R.Topaloglu

Renal Pathology Typical swan neck deformity of

proximal convulated tubules seen at 6 monts

Other typical features: irregularities of proximal tubular cells (flat cells without brush boarder and large cells with hyperchromatic cytoplasm)

Gl may appear normal generally contain giant multinucleated podocytes

Cystine crystals located in the lysosomes or in cytoplasm seen within interstitial cells rarely within podocytes

Late stage Progressive tubulo-interstitial lesions interstitial fibrosis, tubular atrophy

NEJM 2002 ; 347:111 Am J Kidney Dis 2008;51:893 KI 2008; 73:782

Glomerulus with multiple

multinucleated podocytes and parietal

epithelial cells (HE).

Interstitial cells display

cytoplasmic crystalline

inclusions (toluidine bluestain)

Interstitial cells containing multiple

clear, elongated, needle-shaped and

rhomboid cytoplasmic

inclusions(EM )

R.Topaloglu

Renal functions

In infancy or early childhood serum Cr is generally not elevated

In the absence of Rx creatinin clearance decreases

Among 205 European patients before cystiamine threapy end Stage renal failure developed at mean age 9.2 years

Some have unexplained pleteaus in the renal functions for months to years

Some have rapid deteriotions triggered by an acute infection or by dehydration

Proc Eur Dial Transplant Assoc 1983;19:582-589

R.Topaloglu

Renal Function treated and Untreated Cystinosis Patients, According to Age

●33 untreated patients (1960-1992) ▲ 28 patients treated during at least 10 years, beginning before age 3 (mean age : 17m) Age at which serum creatinine reaches 10 mg/dl has been shifted from 10y to 23y NEJM 2002

R.Topaloglu

Renal transplantation in cystinosis

No recurrence of cystinosis in renal graft

• graft biopsies: cystine crystals in invading host cells, but not in tubular or glomerular epithelium

Living-related transplantation with heterozygote parent’s kidney is allowed

R.Topaloglu

Superior renal graft survival in

cystinosis

Broyer et al. 1981, EDTA paediatric registry • n=47 patients with cystinosis

• 1 year patient and graft survival compared to other primary renal diseases: 89% versus 81% and 81% versus 67%

Kashtan et al. 1995, NAPRTCS data • superior survival of renal grafts in cystinosis

Niaudet, 2006, DIVAT, France • n=23 patients with cystinosis

• at 16 years follow-up graft survival in cystinosis 80% versus 65 % in other primary renal diseases

Van Strelan et all 2011, ESPN and ERA-EDTA Registry • n-=245 patients

• 5 year graft survival compared to other renal diseases (94% versus 84 % )

• Improved 5 year graft survival and the renal function over the last 20 years among NC patients before 1990 graft survival 86% after 2000 100%

R.Topaloglu

Extrarenal complications and long term complications

Endocrine system: Growth Retardation, Hypothyroidism, Diabetes Mellitus, Male Hypogonadism

Eye involvement

Myopaty, Swallowing difficulty

Pulmonary dysfunction

CNS inolvement

R.Topaloglu

Eye Involvement

Band keratopathy which can impair vision Pigmentary retinopathy – impaired color vision and impaired night vision

corneal cyristals

R.Topaloglu

GI Complications

Untreated or undertreated patients develop GI symptoms in 2nd or 3rd decade of life

Spectrum of involvement diverse

77% have feeding abnormalities- reflux, dysmotility, pseudo obstruction, swallowing dysfunction

Mild hepatomegaly , portal hypertension

Exocrine pancreatic insufficiency

Inflamatory bowel disease

R.Topaloglu

CNS involvement in children

intra cranial pressure may increase due to cystine deposition

Pseudotumor cerebri

CSF normal except elevetad intracranial pressure

In some cases acetazolamide is enough in some ventriculo peritoneal shunt is needed

Convulsions, spasticity

Some have abnormal EEG without seizures

Low visual memory may be related to cortical atrophy

Phycosocial difficulties

R.Topaloglu

Late CNS Involvement

Most commonly a generalized cerebral atrophy on CT

Occasionaly calsifications of basal ganglia

Extensive demyelination

Cystinotic encephalopathy - cerebellar and pyramidal signs, mental deterirotion , pseudo-bulbar palsy

- stroke like episodes

Correlates directly with age

Pediatr Nephrol 2008;28:863

Pathogenesis could be related to neuro toxicity involving oligodendrocytes

R.Topaloglu

TREATMENT

Treatment of Fanconi Syndrome

Treatment of cystine accumulation-Cystine depleting treatment

R.Topaloglu

Symptomatic Treatment for Fanconi

syndrome

This treatment may delay kidney failure and improve growth

provision of large amounts of water and sufficient food

nasogastric tube or gastrostomy in infants

potassium and sodium as bicarbonate (or citrate) , in 3-4 doses

Phosphate supplement, serum phosphate level = 3-3.5mg/dl

Ca supplementation

1α OH D3 to cure rickets 0.5-1.5 µg/d

to prevent rickets 0.1-0.3 µg/d

Carnitine supplementation 100mg/kg/day ?

Indomethasine -effects on polyuria & electrolyte supplement Starting age usually 9 months

R.Topaloglu

Cystine Depleting Therapy

Cysteamine

In cysteamine-treated lysosomes (c), cysteamine combines with half-cystine (cysteine) to form a

mixed disulfide cysteine-cysteamine, which uses the lysine transporter to exit the lysosome

Gahl et al, NEJM 2002

R.Topaloglu

Adequet treatment with cystine depleting agent

Significantly reduces the rate of progression to ESRF

Improves growth retardation

Postpones even prevents the extrarenal complications

hypothyroidism,

myopathy

pulmonary dysfunction,

DM

Cysteamine does not influence

Delayed puberty

Primary hypogonadism in male

Male infertility

Systemic cysteamine does not prevent corneal cysteine crystals , a need for topical cysteamine eye drops

R.Topaloglu

Monitorising the treatment

Leukocyte cystine levels

Adjust dose to maintain leukocytes cystine at less than 1 nmol ½ cystine /mg protein

R.Topaloglu

New treatment options

Anti inflammatory drugs? (jasn 25:1163;2014)

Inhibition of intracellular Clusterin and increasing cell viability attenuation of apoptosis in cystinosis cells (jasn 26:612;2015)

Treating chaperon mediated autophagy impairment that contributes to cell malfunction in cystinosis (EMBO Molecular Medicine 7:158;2015)

N acetyl cysteine- oxidative stress was reduce and renal function significantly improved during 3 months period (Ped Nephrol 29:1097;2014)

Folate pro-drug of cystamine as an enhanced treatment for nephropathic cystinosis (Bioorg Med Chem Lett. 21:2502; 2011)

Bone marrow transplantation (Blood 114:2542;2009 Kidney Int 79:1198;2011)

Hematopoeitic stem cell (Stem cell 33:301;2015)

Gene therapy

Gene repair

R.Topaloglu

Summary

Early diagnosis and adequate treatment is the key factor

Cystine depleting treatment slows down the progression of renal and extra-renal symptoms of cystinosis and should be administered as early as possible after the diagnosis and should be continued life-long (also after renal transplantation)

The administration of the recommended doses of cysteamine should be given

Ongoing research on new treatment modalities will improve the future of patients with cystinosis

R.Topaloglu

Questions

How one can suspect cystinosis in an infant ?

What is cystinosin ?

What is the most common endocrine

complication in cystinosis

Could the parents be donor ?

How is the graft survival in cystinotic patients

?

R.Topaloglu